CHAPTER 5

ANIMALS

ENTER CHAPARRAL and stand quietly for a moment. You are almost certain to hear the insistent, repetitive trill of a Wrentit, and the scratching sound of a California Towhee rummaging through the leaf litter in search of invertebrates. A Western Whiptail lizard may catch your eye with its jittery movements as it hurries from bush to bush, while a motionless Coast Horned Lizard will be noticed only when its tongue darts out to capture a harvester ant. A careful eye can find the footprints of a kangaroo rat and perhaps the entrance to its burrow. Examination of the base of large old shrubs may reveal the impressive stick nest of a wood rat. Perhaps one of its more interesting collections, such as a skull of another animal, can be seen in among the sticks. Walking farther requires watching for the Western Rattlesnake, which might be unobtrusively curled up anywhere. In warm weather, flies buzz above the shrubs and are snapped up by the sallying Ash-throated Flycatcher. After a winter rain you might encounter an ambling Ensatina Salamander that has just emerged from its basement-level shelter in a wood rat's nest. Visit at dusk and you will hear the stacatto tail drumming of wood rats, announcing their presence to one another. Just after daylight, near the edges of trails and roads, you are apt to see deer browsing with deliberation. If you are very lucky you may spot a Bobcat or Mountain Lion hunting for its dinner. There is always abundant evidence of chaparral's animal inhabitants. Most species are present year-round, and their activities are an essential part of the functioning of chaparral ecosystems. Encounters with animals are an important ingredient in the complex flavor of the chaparral experience.

Like the plants, the animals of chaparral must live with the rigors of a mediterranean climate. Temperature extremes and the scarcity of water for much of the year are the major factors that determine activity patterns and lifestyles. As a consequence, most mammals are nocturnal or crepuscular (active at dawn and dusk) because these are the coolest parts of the 24-hour daily cycle. These animals spend their days in underground burrows, rock crevices, or insulated nests that protect them from the high daytime temperatures. Reptiles, some birds, and many insects active during the day typically control their temperature by alternating between sunlit areas and the shady branches or cool soil beneath the shrub canopy. In winter when temperatures are too cold, some of these animals hibernate or otherwise become dormant. Seasonal changes and fire provide additional variations and resources, as do the different elevations and the varying topography on which chaparral is found statewide. The chaparral as a whole contains more species of mammals, birds, and reptiles than most other ecosystems in California because of these features.

Animals are unlike plants in that they move from one place to another to achieve a comfortable environment. For the chaparral, this means that many animals with good mobility and a range in diet may be present at some times and not at others. Most can live in other habitats. For example, wide-ranging animals such as Mule Deer, California Towhees, Coyotes, and Western Rattlesnakes live in chaparral, as well as in forested areas, grasslands, and many other habitats. However, a relatively smaller number of animals is particular only to chaparral. In this chapter we focus first on those animals that are chaparral specific and whose biology is known. For example, wood rats, Wrentits, Pacific Kangaroo Rats, California Whipsnakes, and harvester ants are particular to the chaparral. Among these are animals with intriguing habits and special adaptations to chaparral. The amount of information for mammals, birds, reptiles, and insects is uneven, however, as are their numbers. Some of the best stories of adaptation to chaparral are found among the insects, yet overall, this is a poorly studied category. Besides those animals particular to chaparral, we also include the more common wide-ranging animals that frequent chaparral and may be encountered by a visitor. Chaparral animals often avoid the harsh glare of open sunlight, and many do not leave the protective cover of the shrubs by day, or are entirely nocturnal. Seeing these multitalented inhabitants takes some patience and care.

Mammals

Thirty-eight species of terrestrial mammals, plus about a dozen species of bats, regularly occur in chaparral. This is approximately 25 percent of all those found in California. Of these, 11 rodents and one rabbit are endemic to chaparral. Rodents are the most common animals in the chaparral throughout the state. Most are directly dependent on the chaparral plants for food and nesting sites. A number have specialized diets of seeds and leaves. Other herbivores such as rabbits, squirrels and chipmunks, deer, and Bighorn Sheep are more general in their habitat and eat a wide range of plants. Carnivores such as foxes, Mountain Lions, Bobcats, and Coyotes are also generalists. These animals use the chaparral for hunting, as they do forests, deserts, and other habitats.

Rodents (Order Rodentia)

Approximately 21 species of rodents inhabit the chaparral. Of these the most common are the wood rats, kangaroo rats, and white-footed mice. Typically, these animals feed on seeds, foliage, and insects. They are small and agile, and many prefer to move along the stems of the shrubs rather than on the ground. They have acute hearing, excellent vision, and a good sense of smell. They are also good at moderating their temperature and water loss through a combination of behavior, nest construction, and physiology. To avoid overheating and water loss, as well as predators, they are active at night (nocturnal) or at dawn and dusk (crepuscular). Either end of the day is a good time to look for these animals, and it is also the time of day when the diurnal (day-active) birds, reptiles, and insects cross paths with more nocturnal species, like factory workers changing shifts. Usually only a few species of rodents (two to eight) are found in any one area of chaparral. Some are highly territorial and will defend their feeding and nesting areas against other members of the same species. The particular species present and their relative numbers change markedly with the age of the chaparral relative to the last fire.

Wood Rats

Wood rats (Neotoma spp., family Muridae) are the signature animal of mature chaparral throughout the state. These nocturnal rodents, also known as pack rats or trade rats, may weigh up to two pounds and are the largest of the chaparral species. They have large ears, bright eyes, and a pleasantly intelligent look about the face. They are gray brown and rather chunky looking for a rodent, with a body eight to 10 inches long and a tail of equal length (fig. 36). The Dusky-footed Wood Rat (N. fuscipes) occurs in northern California chaparral, while the Big-eared Wood Rat (N. macrotis) occupies chaparral in southern California. Wood rat numbers increase as chaparral shrubs age and increase in size. Their favored habitat is among scrub oaks (Quercus spp.), where the solid horizontal limbs serve as pathways to and from foraging areas and nests, which may also be in among the scrub oak branches. These rats prefer to travel along branches rather than on the ground, where the rattle of leaves might give them away to would-be predators. Since a wood rat is a relatively heavy rodent, this branch-traveling behavior is only possible where the shrubs have grown large. Scrub oaks, toyon (Heteromeles arbutifolia), California coffeeberry (Rhamnus californica), and other more treelike members of the chaparral are their preferred habitat. Since these shrubs are often found in ravines or on moister north- and east-facing slopes, these are likely places to find wood rats. They are nocturnal and can see and hear well in the dark, and they also have an excellent sense of smell.

Figure 36. A Big-eared Wood Rat sitting on a resting platform upon its stick nest.

Wood rats are notable for their large and complex nests made of plant stems and twigs. The nest provides protection from changes in temperature and humidity, as well as from predators. A wood rat adjusts its environment through the architecture and location of its dwelling. On a summer day, temperatures inside a wood rat nest may be 15 to 30 degrees F lower than on the nearby exposed soil surface, and it will stay comfortably warm on a cold winter's night. Because heat is the greatest problem for most of the year, the nests are usually located in cool spots such as north- or east-facing slopes, or in a ravine or rock cave.

A nest is shaped like a small haystack and can be up to five feet high and 10 feet wide (fig. 36). Its construction is by no means haphazard despite its jumbled appearance. Twigs, leaves, branches, and other plant parts are firmly woven together to create strong walls on the outside. Inside are numerous chambers, trails, verandas, food caches, and more. Large nests may contain several living and sleeping areas, a larder, and exterior platforms used as latrines. In addition to its aboveground rooms, the nest incorporates tunnels and ground chambers for protection and escape. The nests are surprisingly roomy. If the ratio between the volume of a wood rat's body and the volume of its nest were applied to human dwelling space, a person would have a 13 by 13 foot room, or about the floor space of a modest American bedroom plus bath. Many of the chambers and other spaces are so large that other kinds of animals use the nests as uninvited and often unnoticed guests; there's a whole ecosystem inside them (see below).

Finding food and plant materials for their nests is a daily, year-round activity for wood rats. Since the chaparral is evergreen, fresh plant food is always available. Wood rats have a broad vegetarian diet. They consume seeds, buds, flowers, and leaves and specialize on the moist, nutrient-rich cambium tissues just below the bark of the chaparral shrubs. Cambium is especially important in late summer and fall when many other plant foods are unavailable. In pursuit of this moist tissue, they gnaw bark, twigs, and branches off of the shrubs, eating some and piling others on the nest, thus maintaining its strong exterior. Parts of virtually all shrubs close to the nest will be used as food. If an animal finds something good to eat on the journey out from the nest, it will be eaten on the spot. If there is a rich supply of a preferred food such as acorns or California coffeeberries, rather than eating on the road, the food will be brought home and stored in larders, some of which can hold up to 20 pounds of food, 10 to 15 times the body weight of the animal! When eating at home a wood rat often dines on the lookout porch or terrace near the entrance to its house, where it can survey the surrounding terrain and watch for predators.

While their native food and housing materials are the plants of the chaparral, wood rats may incorporate any interesting item that comes their way. In nature these items might be small animal bones including skulls, pieces of cactus, dung of larger animals, or bits of bird nests. When people are in the area the items may be more unusual. Nests have contained surveyors stakes, broken bottles, tin cans, nails, baling wire, automobile bolts, pieces of inner tubes, newspapers, plastic bottles, sweatshirts, pliers, and miscellaneous household objects! Wood rats have the intriguing habit of leaving an item in the place of the one taken; a small stone or twig will replace a shiny button, for example. Since the rat carries objects in its mouth, if it already has an item and encounters another that it finds more attractive, then it must put the one down to pick up the other. This habit of seeming to exchange one item for another explains its other common name, the Trade Rat. There are countless stories of wristwatches, rings, coins, and the like being exchanged for twigs, rocks, and other such items. A fun but unlikely story is that of a wood rat taking a small object from a miner's camp and leaving a gold nugget in exchange.

The nests, like rental houses, are occupied over the years by a succession of tenants. It is generally safer and more efficient for a young animal setting up housekeeping to move into an empty nest rather than start an entirely new one. Each nest usually has only one adult resident at a time because these species are highly territorial, and one rat will drive others away. Wood rats often occur in dense populations in mature chaparral, reaching about 16 adults per acre. This tight packing is possible because each rat forages close to its nest and rarely runs directly into another rat's territory.

A wood rat house is a ready-made habitat for a host of other animals that find shelter and food in this cozy environment. These hangers-on and inadvertent guests use the temperature stability and physical protection of the wood rat's house to their advantage. Among the most interesting denizens of these nests are the Giant Flea, the fungus-feeding beetles, and the bot flies.

The Giant Flea (Hystrichopsylla dippieei, family Hystrichopsyllidae, order Siphonaptera) is a common member of Dusky-footed Wood Rat households in northern California. For a flea it is huge. The female can be .25 inches long rather than the pinhead size (less than .03 inches) of ordinary fleas. These fleas can jump only two to three inches because they are so large. However, once inside the wood rat's living chamber there is no need for long leaps. They settle onto their rat hosts, which then supply the flea with food and water. The population of large and ordinary small fleas in a single nest can range from less than 100 to well over a 1,000 individuals.

Cryptophages (family Cryptophagidae, order Coleoptera), a specialized group of beetles that are found in wood rat houses, eat the fungi that grow thickly on decaying plant matter in the lower reaches of the nest. After a wood rat has eaten most of a twig, it may drop the leftover bit on the floor. As this garbage piles up it becomes a perfect source of food for fungi that live on decaying plant material. As the fungi eat the leftovers of wood rat dinners, they themselves become dinner for the fungus-eating beetles.

Bot flies (Cuterebra spp., family Cuterebridae, order Diptera) have an obligatory and peculiar relationship with chaparral wood rats. The adult bot fly lays her eggs near the entrance of the nest. After hatching, the young larva drops on a passing wood rat and quickly burrows inside the warm body. As it grows it moves just beneath the skin and forms a chamber, called a warble, which protrudes from the body. The larva grows to an inch in length, feeding on the body fluids of the rat. The center of the bulge has a breathing hole for the larva within, which can be seen squirming within through this small opening. At maturity the larva drops out of the hole onto the ground and then pupates. Grotesque and traumatic as these warbles appear, they quickly heal when the larva departs, and they seem to do no permanent harm to the host. About 50 percent of all wood rats will have one to eight bot fly larvae in their bodies during spring and early summer.

In addition to these invertebrate specialists, many kinds of spiders, ants, beetles, centipedes, and pseudoscorpions are regularly found in and around wood rat nests. There is even a mouse that lives in the nest at times (see California Mouse [Peromyscus californicus]). All these animals are attracted to the many resources of this special environment, which are otherwise unavailable in chaparral. Nests also often shelter Ensatina Salamanders (Ensatina eschscholtzi), which otherwise could not live in most chaparral because it is too dry. Although uninvited, these houseguests seem to be accepted by wood rats without conflict.

The Desert Wood Rat (N. lepida, family Muridae) is found in recently burned chaparral and open chaparral, particularly on very steep and rocky slopes (pl. 62). It also occurs on all the deserts of California and the Great Basin, hence the common name. It is similar in appearance to the Dusky-footed Wood Rat and the Big-eared Wood Rat, but somewhat smaller in overall size. The Desert Wood Rat has a catholic diet of various plant parts and plant species, including the succulent tissues of prickly pear and cholla cactus (Opuntia spp.). Juicy cactus tissues contain oxalic acid, which in large quantities is poisonous to most mammals, but it leaves the Desert Wood Rat unaffected. Its nest is constructed from sticks, twigs, pieces of cactus, and other portable objects piled over holes or openings between rocks. Rock outcrops and patches of cactus are particularly favored. The assortment of twigs and debris over a Desert Wood Rat nest is never as extensive or well organized as the elaborate structures of the Dusky-footed and Big-eared Wood Rat. A Desert Wood Rat nest is most easily found by inspecting rocky areas and cactus patches for the odd little piles of material placed across openings to nests. If a Desert Wood Rat is living within, piles of dark feces about the size of cooked rice grains will be found on the tops of nearby rocks or boulders.

Kangaroo Rats

Another characteristic group of chaparral rodents are the kangaroo rats (Dipodomys spp., family Heteromyidae). They are easy to recognize with their wide triangular heads with large, round shiny black eyes stuck on the sides like onyx jewels, long hind legs and stubby front legs tucked up under their chin, and a very long dark and white tail tipped with a bushy tuft of long hairs (fig. 37). They weigh 1.7 to 3.5 ounces, and more than half of their 10.5 to 13.4 inch head and body length is due to the tail. Five species that look very much alike are found in chaparral, but each local area has only one species. The Delzura Kangaroo Rat (D. simulans) and the Pacific Kangaroo Rat (D. agilis) occupy the chaparral through Baja California and the Transverse Ranges of southern California. Heermann's Kangaroo Rat (D. heermanni) replaces them in the Central Coast Ranges and the foothills of the southern and central Sierra Nevada. The Narrow-faced Kangaroo Rat (D. venustus) is found in the chaparral and coastal scrub of the Central Coast Ranges, between northern San Luis Obispo County and the Bay Area. These species are replaced in the chaparral of northern California by the California Kangaroo Rat (D. californicus). These five species are similar in size, appearance, behavior, and habitat requirements. All are nocturnal. Field studies suggest that they are ecological equivalents. That is, they have the same role in each chaparral community. Kangaroo rats are especially abundant in the first few years after a chaparral fire when large spaces between the shrubs provide clear space for hopping about, but they can be found in most chaparral with patches of open ground. Kangaroo rats do not occur in chaparral where the soil is too hard, thin, or rocky for digging, or on steep slopes.

Plate 62. A Desert Wood Rat, often associated with rocks and cactus in chaparral.

Figure 37. A Pacific Kangaroo Rat holding a grass seed, with burrow, burrow mound, and underground chambers shown below.

Kangaroo rats get their name from their hopping style of locomotion that resembles that of the kangaroo. As a kangaroo rat hops along the ground covering several feet in each leap, the tail, held high in an upturned arch, switches from side to side with each bounce. This tail switching shifts the animal's center of gravity at the start of each hop, causing its path of travel to zigzag this way and that. This behavior is thought to be a defense against predators in hot pursuit, who may snap futilely at the tantalizingly conspicuous white tail tip that is in constant, erratic motion. Even if the predator snaps off the end of its tail, the kangaroo rat can do without it.

Seeds are the basis of the kangaroo rats' existence. They forage for surface and buried seeds, using an unusually acute sense of smell that enables them to find pockets of buried seeds by odor. Kangaroo rats have fur-lined cheek pouches in which they stuff seeds until the pouches are full, so that they protrude from the sides of their face as if they have giant toothaches on both sides. They return to their burrows to empty the pouches and set out again to hunt for more, making several trips each night. Kangaroo rats are strictly nocturnal, so they avoid the desiccating daytime heat and the visual predators that hunt by day.

Kangaroo rats have a unique metabolism based upon their diet of seeds. Not only do the seeds provide energy, but directly and indirectly, they also provide water. Unlike many other species of chaparral animals, kangaroo rats never drink water. Instead, their digestive system breaks down the oils and stored fats of the seeds, which releases water as well as energy. This metabolically derived water is absorbed and retained by the body. In captivity, kangaroo rats from chaparral will eat succulent plant foods to supplement water made from seeds.

Kangaroo rat burrows are very well designed to trap and conserve humidity in the air, to maintain a comfortable range of temperatures year round, and for protection against predators and wildfires. The burrows are one to two feet deep in the ground, with curving tunnels and various chambers for resting and food storage (fig. 37). The soil provides such an effective buffer from the surface environment that temperatures in the deeper portions of the burrow vary by less than 20 degrees F over the entire course of a year, regardless of summer heat and winter cold. The burrow traps air and holds it in still pockets, so that the air has a higher relative humidity than does outside air. The moisture in the burrow atmosphere is further increased when the entrance is sealed during the day. A burrow system that has existed for several generations of occupants can have multiple entrances, with a complex of tunnels and chambers that are as much as five feet across. An observer walking across the top of a burrow complex will often feel the ground under foot give way slightly as shallow tunnels are caved in. The atmosphere within kangaroo rat burrows also contributes water to their diet. Having the air in the burrow more humid than the outside air allows seeds that have been stored as food to absorb some atmospheric water. When the kangaroo rats eat those stored seeds, they gain that much more water in the bargain. Because the burrow air is comparatively humid, the amount of water lost from evaporation by respiration is also reduced.

In daylight, the presence of kangaroo rats is most easily detected by looking for burrows and for depressions from their dust baths. Burrows have openings two to four inches across, leading to a sloping tunnel. These openings may be unobstructed or closed by dirt plugs during the day. As shown in fig. 37, some burrow entrances have a slight mound on one side, where the digging rat has kicked dirt out and away from the tunnel. In places where a burrow has existed for a long time, it may lie beneath a slight mound made from the castings of generations of kangaroo rats throwing excavated dirt in all directions. Kangaroo rats must regularly take dust baths to condition their long, silky fur. These baths leave slight depressions, six to 12 inches across, covered with powdery dust. The characteristic tracks of kangaroo rats can be seen in and around these baths, as well as in other places with loose soil, as a pair of ski-shaped prints about .7 inches long, with a tail trace between. The best time to look for seed excavations, tracks, and dust baths is in early morning, when the low angle of the sun casts shadows in fresh depressions, and before the day's wind has blurred the marks of the previous night's activity.

Unlike almost all other species of small mammals, kangaroo rats often survive chaparral wildfires. They do so by remaining in their well-protected burrows. At the depth of their nest chambers, temperatures increase during a summer fire from perhaps 75 degrees F to a temperature in the 80s, which is cool enough for their survival. Dirt plugs at the entrances, plus the fact that hot air rises, prevent toxic combustion gases from entering the burrow, even if the entrance is unplugged. The aftermath of the fire is the open ground preferred by kangaroo rats, and seeds buried at depths of more than three-quarters inch remain intact as food. Consequently, fire creates and enhances habitat for these animals, so that their populations increase severalfold after a chaparral wildfire.

Kangaroo rats also have a specialized system of waste elimination that uses much less water than that of most other mammals. Their urine is concentrated to the consistency of paste, and the feces are so dry as to have the qualities of little black pebbles. Additionally, before air is exhaled from the lungs, the water in the moist breath is condensed and reabsorbed in special nasal passages. Kangaroo rats lose less than half as much water by evaporation as either white rats or humans, in proportion to their size. They can survive, under laboratory conditions, on a diet of nothing but dry seeds and salt water!

White-footed Mice

Five species of white-footed mice (Peromyscus spp., family Muridae) inhabit chaparral, the California Mouse (P. californicus), the Brush Mouse (P. boylii), the Cactus Mouse (P. eremicus), the Deer Mouse (P. maniculatus), and the Pinyon Mouse (P. truei). As a group they are medium sized rodents, six to 11 inches long including tail, with chestnut brown backs, and bellies and feet that are white. White-footed mice have a broad diet that includes fruits, flowers, seeds, leaves, arthropods, and fungi. The five species vary in abundance according to location and the structure of the plant community, which is a function of the time since fire.

In the mature chaparral, the California Mouse is the common species of this genus. It is found in all dense chaparral from San Francisco Bay southward to Baja California in the Coast and Peninsular Ranges, and throughout the Sierra Nevada foothills from Mariposa County southward. It prefers the same range of dense, shrubby habitats as do wood rats. The adult California Mouse is dark brown on the back, and it has a chunkier body than other white-footed mice, weighing one to two ounces (fig. 38). Besides building its own nest, it sometimes occupies the nest of a wood rat as a tolerated squatter, which explains its older common name, the Parasitic Mouse. The California Mouse and the Brush Mouse are partially arboreal, climbing among the stems and branches of shrubs with agility, using their long tail like a monkey does, as a fifth grasping appendage, and for balance. This is especially true of the California Mouse, which prefers to move about above ground. A California Mouse will climb out to the end of a branch so small that it bends under the animal's weight, and then deliberately leap across a short gap to the branch of an adjacent shrub. This species makes ball-shaped nests from twigs, generally placed high up in the shrubs. These mice form long-term pair bonds, and the parents share in care for the young and defense of the nest. The Brush Mouse looks like a slightly smaller, leaner California Mouse (pl. 63). Where either the California or Brush Mouse is common, the other species is usually rare or absent.

Figure 38. A California Mouse on a manzanita branch. Note how the tail is used for grasping the branch.

Plate 63. A Brush Mouse. The long tail, useful in climbing, is indistinctly striped and has a thin tuft of hairs at its tip.

For a year or two following chaparral fire, the common and wide-ranging Deer Mouse is often the most numerous species of rodent in chaparral. Within its continental range this mouse often plays the role of an opportunist, making first use of the disturbed habitat created by the fire, before competing species of rodents arrive. In postfire chaparral its numbers generally decline as populations of other species of Peromyscus, and other rodents, increase. The Deer Mouse does not climb, and as shrub cover develops it is largely replaced by the climbing species of white-footed mice. In mature chaparral, if it is present at all, the Deer Mouse is found in whatever open spaces exist, and at edges between chaparral and other plant communities.

In southern California the Cactus Mouse is often the second species of Peromyscus to occur in numbers after chaparral wildfire, displacing the Deer Mouse within a few years. It is somewhat smaller than the Brush Mouse, with a nose-to-tail-tip length of about six to eight inches, and a weight of .7 to one ounce. The upper body is gray brown and the long tail is thinly haired. It is most common in postfire chaparral at the stage when there is still some space between the shrubs, while herbaceous plants and seeds are common. It is also found in chaparral with scattered shrubs, and in other plant communities with shrubs and cacti, throughout the American southwest and northern Mexico. The maximum population densities of the Cactus Mouse are lower than peak densities of other white-footed mice, and sometimes more seasonally variable.

Plate 64. The Pinyon Mouse has unusually large, rounded ears for a white-footed mouse.

In southern California the Brush Mouse displaces the Cactus Mouse three to five years after fire. It generally prefers shrubby vegetation that is somewhat more open and dry than the California Mouse, the specialist of mature chaparral, but the two may coexist in some areas where the chaparral includes irregularities such as rock outcrops that offer a mixture of habitat types.

The Pinyon Mouse is a moderately large white-footed mouse, with a head and body length of 3.5 to four inches, and a distinctly striped tail about the same length (pl. 64). It is most easily recognized by its large, rounded, Mickey Mouse ears that are about one inch long. The species is widely distributed throughout California in chaparral and other communities where some shrub or tree cover is available. The Pinyon Mouse does not occur in chaparral on the coastal side of the mountains of southern California, where its place seems to be taken by the Brush Mouse. In chaparral these two species seem to compete in places where their ranges overlap.

Harvest Mouse and California Pocket Mouse

Apart from the white-footed mice, two other small mice, the Harvest Mouse (Reithrodontomys megalotis, family Cricetidae) and the California Pocket Mouse (Chaetodipus californicus, family Heteromyidae) are found occasionally in the chaparral. They are particularly abundant the first few years after fire. In more mature chaparral they are usually found along its margins, or in a disturbed area with grasses intermixed with shrubs. The Harvest Mouse is found across most of California and the western United States, usually in places with thick weeds or grasses growing close to the ground. In chaparral it is occasionally found in the first few years after fire, when the ground is covered with dense herbaceous growth. The California Pocket Mouse is found primarily in chaparral and adjacent habitats, from San Francisco Bay and the central Sierra Nevada foothills southward into Baja California. The distribution of this species appears to be spotty, and its numbers are variable. When present, the California Pocket Mouse seems to prefer edges between chaparral and other plant communities.

The Harvest Mouse is the smallest rodent to be found in chaparral. It has a head and body length of three inches, and a tail of approximately equal length. The back is gray to brown, with the belly and underside of the tail white to deep gray. It looks something like a slender House Mouse (Mus musculus).

The California Pocket Mouse is a small relative of kangaroo rats common in chaparral after fire. It has a head and body about 3.5 inches long, with a longer tail with a tuft on the end. The back fur is a mixture of yellow and black hairs, with spiny hairs that stick out on the rump. Like kangaroo rats, it has cheek pouches, and the hind feet are relatively large, but unlike kangaroo rats, it does use both front and back limbs to move.

Squirrels and Chipmunks

Squirrels and chipmunks are rodents belonging to the family Sciuridae. They occur in chaparral but are generally more abundant in forests, woodlands, and open areas adjacent to chaparral. The California Ground Squirrel (Spermophilus beecheyi) is the most widespread squirrel in the state and the only species found around the edges of chaparral. It is easily distinguished from the Western Gray Squirrel (Sciurus gresius) and other tree squirrels because it lacks a thick bushy tail, is usually seen on open ground, and does not climb or keep near to trees. Around chaparral, the California Ground Squirrel is generally found near human disturbances such as road cuts, plowed areas, and agricultural fields. It has expanded its range into areas of chaparral where roads, trails, power line rights-of-way, and islands of urban development have dissected the previously impenetrable shrublands. It digs extensive burrows and forages in disturbed areas with relatively open ground. The California Ground Squirrel is not commensal with humans in the sense of the House Mouse and Roof Rat (Rattus rattus), sharing our dwellings, but it does invade and occupy open landscapes created by human activities.

Chipmunks (Tamias spp.), like squirrels, are associated with openings and disturbance in chaparral and woodlands, especially those caused by people. Three species of chipmunks can be found in chaparral. Merriam's Chipmunk (T. merriami) occupies the chaparral of southern California through the Coast Ranges to San Francisco Bay, and the foothills of the southern and central Sierra Nevada. The Sonoma Chipmunk (T. sonomae) replaces it in northern California. The Obscure Chipmunk (T. obscurus) occupies chaparral of the Transverse and Peninsular Ranges of southern California and Baja California. All chipmunks are easily recognized by their size, with a head and body length of about nine to 11 inches, a bushy tail somewhat shorter than the body, and a brownish color with distinct light and dark stripes from nose to rump (fig. 39). One of the dark lines always passes through the eye. Even the most casual observer usually notices chipmunks, because they are busy in the daytime, noisy, and often conspicuously perched on little vantage points such as rock tops, where they make a scolding chatter when approached. Unlike their cousins, the kangaroo rats and white-footed mice, chipmunks are not found in burned areas of chaparral.

Figure 39. A Merriam's Chipmunk. Unless foraging on the ground, as shown here, it is more likely to be perched on a log or some other raised vantage point.

Rabbits and Hares (Order Lagomorpha)

Rabbits and hares are members of the family Leporidae. Three members of this family are found in chaparral: the Brush Rabbit (Sylvilagus bachmani), the Desert Cottontail (S. audubonii), and the Black-tailed Jackrabbit (Lepus californicus), also known as the Black-tailed Hare.

The Brush Rabbit is a true creature of the chaparral and is rarely found elsewhere. It has a head and body length of 11 to 13 inches, with charcoal-tinged brownish fur, and relatively short legs and ears. The Brush Rabbit tends to be nocturnal, rarely venturing beyond the dense brush, so that it is difficult to see. It rests and breeds in small openings, called forms, made in tangles of vegetation beneath shrubs. Its somewhat larger cousin, the Desert Cottontail (fig. 2), is found where chaparral is patchy, especially around the edges between thick shrubbery and openings. This is the rabbit that people are most likely to see in chaparral, as it is much less retiring than the Brush Rabbit. Both species feed primarily by grazing on grasses and other herbaceous vegetation. Their persistent feeding is an important cause of the general lack of herbaceous growth beneath and between mature chaparral shrubs.

The Black-tailed Jackrabbit is primarily a creature of the desert and open dry shrub communities. It is found in chaparral in recent burns and at the margins between shrublands and other plant communities, where it may use its long, easy bounds between shrubs to escape predators. It is large compared to the other two species, with long hind limbs, a short dark tail, and very large dark ears. The big ears dissipate heat and therefore help to keep the animal cool even under the hottest conditions.

Deer and Bighorn Sheep (Order Artiodactyla)

Two large herbivorous animals are found in chaparral: deer (Odocoileus hemionus, family Cervidae) and Bighorn Sheep (Ovis canadensis, family Bovidae). Both belong to the order Artiodactyla, a group of two-toed herbivores that also includes pigs and cattle.

Deer are common in chaparral throughout the state (fig. 40). The two subspecies living in southern California and the Sierra Nevada are called Mule Deer (O. h. subsp. fuliginata and O. h. subsp. californica), due to their large ears, while the subspecies of the North Coast Ranges and northern California is called Black-tailed Deer (O. h. subsp. columbiana), because of the dark color of the upper surface of its tail. In addition to a large number of plant-eating rodents, deer are also important herbivores in the chaparral. They frequent chaparral after fire but are rarely found when the shrubs are fully developed and dense. This is because deer feed on grasses and forbs that are not present in the understory of mature chaparral, but that are a major feature of the postfire chaparral landscape in the first few years. They are seen even in mature chaparral; however, more forage is available along the edges of chaparral stands and in canyons. The density of deer populations in chaparral varies in time and space, with generally higher numbers in the northern part of the state. Deer are attracted to recently burned areas of chaparral, particularly when fires have been patchy, leaving open areas with lush vegetative growth adjacent to dense shrubs. As time passes, the capacity of burns to support deer gradually declines as the spreading shrubs close the gaps. If other chaparral patches are burned nearby, the deer herd as a whole can be indefinitely supported at a moderate level because a shifting matrix of edges between old and young vegetation is maintained.

Figure 40. A Mule Deer standing near a small toyon shrub. The large ears, as shown, pivot independently to pick up sounds.

When young growth is present, deer prefer certain shrubs, such as mountain mahogany (Cercocarpus betuloides), ceanothus (Ceanothus spp.), and toyon, and generally avoid others, such as manzanitas (Arctostaphylos spp.). Under some circumstances, persistent browsing of preferred plants is sufficient to shape the structure and species composition of chaparral plant communities. In northern California and at higher elevations in the south, deer herds practice seasonal migration, moving in winter to lower elevations where there is less snow and more food. Some deer in southern chaparral move over shorter distances, following food availability by moving from south-facing slopes in winter and spring to north-facing slopes in summer and fall.

The Bighorn Sheep is a grayish brown animal with creamy white rump and horns (pl. 65). It is about the height of a smallish Mule Deer, but with a much chunkier body. The mature male has spectacularly coiled, massive horns that are used for mating combat with other males. These shy animals live in small groups, led by a dominant female, and they are likely to be seen only in remote, rugged areas. Once, two million Bighorns roamed across most of the mountain ranges of the West, but herds in California have dwindled to about 4,000 animals, found in scattered locations in the mountains of southern California, the eastern Sierra Nevada, and deserts. California's Bighorn Sheep are listed as an endangered species by the U.S. Fish and Wildlife Service, and as threatened by the California Department of Fish and Game. In the San Gabriel Mountains, Bighorn Sheep move down from the high mountains in winter and spring to the warmth and new growth of chaparral-covered canyons, where lambs are born.

In the late 1980s the California Department of Fish and Game moved 37 Bighorn Sheep from the San Gabriel Mountains to remote locations in the Sespe Wilderness of Ventura County, where Bighorns had disappeared almost a century earlier. After some initial difficulties, this transplanted herd seems to have increased in size. It occupies a large wilderness area with extensive chaparral. One reason for the small population size is probably the limited habitat value of the old and dense chaparral. Fire could improve the habitat for Bighorns by opening up the chaparral, by providing far more nutritious vegetation, and by improving the ability of the sheep to spot and elude approaching predators.

Plate 65. Bighorn Sheep. The male is the larger animal with curled horns, shown here with two females, photographed at the Living Desert, Palm Desert, California.

Carnivorous Mammals (Order Carnivora)

Carnivores, such as Coyotes, Gray Foxes, Bobcats, Mountain Lions, Black Bears, and Grizzly Bears are found in many communities across the country, and none is specific to chaparral. These animals often utilize the edges of chaparral where it is more open and where there are canyons and ravines associated with it. Despite the scientific classification as carnivores, not all of these species are strictly eaters of meat.

Coyote

One of the most successful and widespread mammals in North America is the Coyote (Canis latrans, family Canidae), and it is becoming more so with each passing year. A Coyote has the appearance of a medium-sized dog, resembling a small, unusually slender German shepherd, but with a more brownish back and rusty-colored ears and legs (fig. 41). The easiest method for detecting the presence of Coyotes is to listen for their cries, especially in the early hours of the evening. Coyote vocalizations are almost always produced by several animals at once and consist of a few brief howls followed by a series of short yips and barks. The howls of one group are sometimes answered by another group in the distance. These sounds are often mistaken for wolf howls, but there are no wild wolves in California. The Coyote is quite flexible in its diet and behavior, often including chaparral with other habitats in its search for food. In chaparral this animal is a hunter of the margins, ranging around edges and disturbed areas in search of rabbits, rodents, and other small animals. A Coyote cannot easily move through dense chaparral, so like us, it avoids it. Consequently, it is most often seen along roads, trails, railroad tracks, and when crossing openings. It is not uncommon to encounter Coyote scat made almost entirely of manzanita berries, which it eats for the semifleshy outer covering. However, the hard inner seeds pass through the digestive tract intact and are dispersed to new locations in the droppings. The tough manzanita seeds require heating by fire in order to germinate.

Figure 41. A Coyote in recently burned chaparral, as suggested by the phacelia plant near the front feet. In colder climates it produces much thicker fur, especially in winter. Consequently, individuals living in chaparral tend to appear thinner and smaller than coyotes elsewhere in North America.

Some Coyotes, especially young males, will commute from chaparral several miles into cities and suburbs at night, either foraging or simply using fence lines, roads, and other thoroughfares to get from one place to another. These commuting predators have a reputation for favoring small pets and refuse for food, but our research has shown most of the diet of suburban Coyotes is wildland food.

Gray Fox

Found nearly everywhere in North America, the Gray Fox (Urocyon cinereoargenteus, family Canidae) within California is probably most common in chaparral (fig. 42). It frequents moderate to low elevations in heavy chaparral, canyons, and rocky places. It is the size of a small dog, with a very bushy tail, about three feet from nose to tail tip. The Gray Fox is not frequently seen, probably because it is mostly nocturnal. As much scavenger as carnivore in its diet, this lithe animal moves easily through dense chaparral and will climb into shrubs to raid bird nests and take sleeping birds. Its droppings, which are seen much more often in chaparral than the animal itself, usually contain far more plant than animal material.

Figure 42. A Gray Fox, one of the more common carnivores of chaparral. The very bushy tail is the most distinctive feature of this small canid.

Mountain Lion

Also called Puma or Cougar, the Mountain Lion (Puma concolor, family Felidae) is a slender, tawny cat with a long, thick, black-tipped tail. Because of its large size, six to 7.5 feet, and distinctive tail, it is not easily mistaken for anything else, although a surprising number of startled people confuse it with the Bobcat (Lynx rufus), which is very much smaller and has a very stubby tail. It has the largest range of any mammal in the Western Hemisphere, from Canadian forests to southern Chile. In California it occurs everywhere except the Central Valley and much of the deserts. It is most common where its principal prey, Mule Deer, are found. It favors chaparral, forests, rocky ledges and slopes, and mountain ridges. The Mountain Lion hunts by stalking and pouncing from ambush, so rugged topography gives it some advantage in leaping onto prey from concealed vantage points. This reclusive, solitary animal is rarely seen, even though it often lives near urban areas, sometimes even within city limits. This species' numbers have been steadily increasing in chaparral and elsewhere in California since hunting them for sport was discontinued in 1972, and the Mountain Lion is now occasionally seen on the edges of chaparral near urban areas.

Bobcat

Although sometimes confused with the Mountain Lion, the Bobcat (Lynx rufus, family Felidae) is much smaller, about the size of a very large house cat. A Bobcat has a stubby tail, broad cheeks, tufted ears, and stripes about the face, so that it resembles a domestic tabby (pl. 66). It occurs across most of the United States and Mexico, but in California, chaparral in steep and rocky terrain is a favored habitat (fig. 43). It is not often seen, even though it is frequently active in daylight. It spends most of its time lying in wait for passing prey, taking advantage of shrubs, rocks, and its camouflage coloration for concealment. A Bobcat's diet consists mostly of small mammals and birds, although given the opportunity it will readily take smaller and larger animals, including small domestic livestock.

Plate 66. The Bobcat's short tail, facial marking, and ear coloring are distinctive, shown here photographed at the Arizona-Sonora Desert Museum, Tucson, Arizona.

Figure 43. A Bobcat in a typical rocky habitat.

Black Bear and Grizzly Bear

The largest mammal inhabiting California chaparral today is the Black Bear (Ursus americanus, family Ursidae), and it is also the one that occurs in lowest numbers. It occurs naturally throughout the chaparral and forests of the Sierra Nevada and the mountains of northern California, and widely throughout North America. A Black Bear generally weighs 250 to 400 pounds, and despite the name, in much of its range the brown color phase predominates, varying from dark, chocolate brown to reddish brown to tan. Since the extirpation of the Grizzly Bear (U. arctos, family Ursidae) from California a century ago, the Black Bear has extended its range across the Tehachapi Mountains and northward into the Central Coast Ranges. It also occurs in the mountains of southern California, where it was introduced by the California Department of Fish and Game in 1932. In chaparral areas the Black Bear is found along the edges of dense brush and in canyons, where it forages for fruits and berries, insects, carrion, and whatever else might come its way.

At the time of the Gold Rush there was a second species of bear in California, the Grizzly Bear. It roamed the valleys and foothills of all parts of the state and was quite common in chaparral. Much larger than the Black Bear, a mature male probably weighed an average of 900 pounds. The last Grizzly in California was killed in the 1920s. This large, powerful, and unpredictable animal has always excited the imagination of Californians. The official State Prehistoric Artifact is a small carving of a walking bear, with the proportions of a Grizzly, made 7,000 to 8,000 years ago. During the Bear Flag Revolt in Sonoma, an 1846 insurrection against Mexican rule led by American settlers, the Grizzly Bear—as a symbol of great strength—was placed on a homemade flag. Soon thereafter, when California became a part of the United States, the Grizzly Bear was once again placed at the center of the state flag and in the foreground of the Great Seal of the state of California. The Grizzly Bear was chosen as a symbol of the independence, strength, and uniqueness of the state. Less than 75 years later it was gone from the California wilderness forever.

Inevitable as the extirpation of the Grizzly Bear might have been, its loss may have altered ecological patterns and processes of chaparral. Because of its numbers and size, this animal may have affected the very structure of chaparral by consuming fruits and distributing seeds, tearing up the soil to get roots and bulbs, and bulldozing openings in otherwise dense shrublands, and perhaps in other ways that are difficult to imagine now that they are gone. The Black Bear may have filled the ecological role vacated by the Grizzly to some degree. However, it is smaller and does not tunnel through the chaparral in the bulldozer fashion of the Grizzly Bear, so its impacts are clearly not the same. The presence of tunnels suggests that Grizzlies may have regularly opened up areas of chaparral that today remain closed and undisturbed except by fire. Largefruited species of shrubs such as scrub oaks, cherries (Prunus spp.), and California coffeeberry are eaten by bears, and they do not require fire to germinate. These plants and others like them, may well have been dispersed and established intermittently in the middle of old chaparral by Grizzlies, a phenomenon that does not occur today. Contemporary footpaths cut through chaparral by humans often stimulate the growth of herbaceous understory plants such as soap plant (Chlorogalum pomeridianum), wild cucumber (Marah spp.), and virgin's bowers (Clematis spp.). Grizzly paths might have done the same. Moreover these paths undoubtedly increased access to dense chaparral for Coyotes and Mule Deer, and the openings would have provided suitable microhabitat at ground level for harvester ants (Pogonomyrmex spp.) and other invertebrates that require sun-warmed soil. The matrix of Grizzly Bear trails could have created and maintained a system for access, distribution, and colonization for a wide variety of plants and animals that are now excluded from extensive, continuous stands of mature chaparral.

The Grizzly Bear was also apparently attracted to areas of recently burned chaparral because these are places with an unusually rich and accessible supply of edible fruits, seeds, bulbs, and tender vegetation. Nineteenth-century visitors to California described remarkable scenes of as many as 20 Grizzlies peacefully congregated around a rich source of food. It is easy to imagine that patches of recently burned chaparral were the scenes of such bear conventions.

Birds

Approximately 50 species of birds are permanent residents of chaparral, and there is a similar number of seasonal inhabitants. The seasonal residents include species that come north from the tropics to breed in spring and summer, such as the Olive-sided Flycatcher (Contopus cooperi) and the Violetgreen Swallow (Tachycineta thalassina). Other species spend their winters in the chaparral and move to the mountains and farther north in summer for breeding. Several other species of birds, including the Western Scrub-Jay, Red-tailed Hawk, and Anna's Hummingbird are also common in and around the chaparral, but they also live elsewhere. The ubiquitous Bewick's Wren is also frequent in disturbed areas and along the edges of chaparral.

A small number of bird species make their home almost entirely in the chaparral. The two that are definitively chaparral birds are the Wrentit and the California Thrasher. The California Towhee and its more colorful relative the Spotted Towhee are consistently found where chaparral is mixed with other types of vegetation. The California Quail feeds around the edges and gaps between chaparral shrubs.

The diversity of birds in chaparral is due to the year-round availability of food. The most common food items for the birds of chaparral are insects and other invertebrates, and seeds and fruits. Insects peak in abundance during spring and summer, but some are present in all seasons. Most fruit and seed production also occurs in spring and summer, but other seasons have enough plant reproduction to support many seed- and fruit-eating birds as well. Trees and the herbaceous plants of chaparral often flower and fruit at times when shrubs do not, and some seeds are present on the ground and in the soil year-round.

Many of the bird species that inhabit chaparral shrubs are short winged, long tailed, and have moderately long legs and toes. These traits suit birds that fly only short distances, flitting through and beneath shrubs, landing on small twigs, and digging in the ground. To the dismay of inexperienced birdwatchers, as a group, most chaparral birds are rather drably colored in grays and browns. Bird-watchers sometimes refer to animals like this as “LBBs” (little brown birds). With a few notable exceptions, it takes more patience to locate birds in chaparral than in more open plant communities, and the lack of showy color patterns requires more careful observations to tell one species from another by sight.

This book describes those bird species most common and likely to be seen in the California chaparral. You are urged to consult one of the widely available field guides on birds for additional information.

Perching Birds (Order Passeriformes)

Wrentit

The most common and characteristic bird of chaparral is the Wrentit (Chamaea fasciata, family Timaliidae). The Wrentit is found in all dense chaparral, from southwestern Oregon to Baja California, and in adjacent plant communities with thick, shrubby vegetation. It feeds by flitting between branches, picking insects and fruits. This bird is rather plain in appearance, about six inches long, and gray brown. Its most conspicuous features are the upward cock of the slender tail and a light yellow eye (fig. 44). Wrentits are always found in pairs because they mate for life and permanently occupy a territory of .75 to 2.5 acres. They build cup-shaped nests in the midst of dense shrubs, well concealed from potential predators. The Wrentit is a weak flyer, but it can hop through the shrubs as rapidly as another species might fly. Since it is willing to fly only short distances, and reluctant to cross large open areas, it spends its entire life under the shrub canopy and may live for as long as 10 years among the tangle of a single patch of chaparral. The Wrentit is the most commonly heard bird in the chaparral. The male's call of three or four accelerating chips followed by a trill, all on the same pitch, is the background music of chaparral. It has been compared to the sound of a bouncing pingpong ball. The female utters the chips without the trill. During spring, as many as a dozen singing males may be heard from one listening point, each busily proclaiming its breeding territory. A Wrentit will sing any time of the day and is often the only bird to be heard in chaparral outside of the breeding season. Heard a hundred times before it is seen, the surest way to spot a Wrentit is to sit or stand quietly in chaparral while producing some imaginative bird sound. A curious Wrentit will investigate the noise by hopping to a branch almost within reach, cocking its head from side to side, to inspect the noise maker with first one yellow eye and then the other.

Figure 44. The tail cocked upward and the short wings are distinctive features of the Wrentit.

California Thrasher

Like the Wrentit, the foot long, red brown California Thrasher (Toxostoma redivivum, family Mimidae), with its deeply downcurved bill and upraised tail, is a hallmark of chaparral (fig. 45). It inhabits all chaparral west of the deserts and below 5,000 feet, from the head of the Sacramento Valley through northern Baja California. It feeds on insects and seeds found in the leaf litter it stirs up with its bill. The Thrasher is a powerful bird that can move rocks and large objects in pursuit of its food. It has a distinct pattern to its foraging activities. First the bird uses its bill like a tiny miner's pick, striking the ground with a rapid series of excavating stabs, and then it switches to a side-to-side motion to clear away any loose dirt. This combination of movements exposes seeds and insects in the litter. The characteristically upraised tail helps to balance the bird during the pulling and digging of its feeding activities. When a desirable food item is located, the Thrasher may continue working away at it until the item is fully extricated. Thrashers eat seeds, fruits, leaves, and a variety of insects. Ants, wasps, and bees are particularly sought after, along with caterpillars, cocoons, and moths. The Thrasher eats many insects that humans consider to be destructive: tent caterpillars, wasps, beetles, and others that find their way into the Thrasher's stomach do not live to eat native or cultivated plants. A Thrasher will move out of chaparral to nearby gardens, where its insectivorous habits benefit the home gardener. This bird's bill grows continuously during its life and may become very long. It continues to grow to counteract the wear and tear of constantly digging in rocky soil. A young Thrasher has a relatively short bill that elongates noticeably after fledging. A Thrasher is a rather poor flyer, preferring to run along the ground or climb around in the bushes rather than fly. It rarely leaves the cover of the chaparral canopy except during courtship singing. You are much more likely to hear one throwing around leaf litter than to see one. California Thrashers have a protracted breeding season, from midwinter until midsummer. The nest, which is maintained by both parents, is well screened in the shrubs and only a few feet off the ground. The birds hold quite still while on the nest and follow circuitous routes to and from the nest, as defenses against predators.

Figure 45. A California Thrasher feeding beneath California coffeeberry. The curved beak, and long tail and toes are useful field marks for identifying this chaparral bird.

Like its Mockingbird (Mimus polyglottos) relative, the California Thrasher is inclined to imitate the calls of other birds and may even use them in its defense. Thrashers have been heard to sing the songs of the Northern Flicker (Colaptes auratus), House Finch (Carpodacus mexicanus), California Quail (Callipepla californica), Black-headed Grosbeak (Pheuciticus melanocephalus), and Robin (Turdus migratorius) and can remember these songs for several months. They can also reproduce the howl of a Coyote (Canis latrans), the call of a Red-tailed Hawk (Buteo jamaicensis), the scream of a Western Scrub-Jay (Aphelocoma californica), and the croak of a frog! Both males and females sing, and they prefer to do so near the tops of shrubs or small trees, which is the only time they are easily seen.

California Towhee and Spotted Towhee

The California Towhee (Pipilo crissalis, family Embarezidae) is frequently seen along the margins of mature chaparral and between shrubs in burned chaparral. It ranges throughout California west of the deserts, around the edges of shrubby vegetation, including that found in suburban backyards. With a thick, conical beak and dusky brown coloration, this 8.5 to 10 inch long bird looks like an oversized, long-tailed sparrow (fig. 46). Paying little heed to nearby humans, and feeding around openings, it is one of the more easily seen birds of chaparral. The California Towhee digs in the litter for seeds, insects, and grubs, although not nearly as earnestly as the California Thrasher. It uses its feet together like a rake, scratching up seeds from around the shrubs with quick hopping motions. California Towhees build a bulky nest in shrubs, close to the ground. They seem to pair for life and spend their entire lives in a small patch of brush. The call of both sexes is a “chink,” which is used to keep the pair together, and the song of the highly territorial male is the same sound repeated three or four times.

Figure 46. The California Towhee is usually seen on the ground, as shown here, near the edge of a shrub.

The Spotted Towhee (Pipilo maculatus) is a smaller, more colorful relative of the California Towhee. It has the same body shape as the California Towhee, but with chestnut colored sides, black head and throat, white belly, black back and wings with white spots, and red eyes. Despite its bright and distinctive coloration, it is seen less often than the California Towhee. The color pattern breaks up its silhouette when it is in dense chaparral and other vegetation. It forages in the thick leaf litter in the same two-footed fashion as the California Towhee. The Spotted Towhee is more inclined to perch on the outside of shrubs, and in small trees, than the California Towhee. You may see one when it moves up to the shrub tops to feed on seasonal fruits, or to sing during the breeding season. The nest is built by the female in dense shrubs, near or upon the ground. The call is a nasal “t-wee,” and the song varies, often a trill in the cadence of “here-here-here-please.”

Bushtit

The Bushtit (Psaltriparus minimus, family Aegithalidae) is a bird that feeds on insects found on chaparral shrubs. It ranges through all chaparral and other shrubby plant communities throughout the western United States. It is a very small bird, about four inches in length, with a longish tail and a short bill. Like most other birds that feed inside chaparral shrubs the Bushtit is plainly colored, with a gray back, a slightly darker cap, and pale underside. It gleans insects from the foliage by perching in almost any position, with the tail cocked this way and that, to best advantage for picking insects off the vegetation. Bushtits forage in loosely organized flocks of 15 to 60, constantly moving from place to place in little waves, while twittering to one another. Despite their small size and drab color they are relatively easy to spot, and even to count, because one tiny party of birds follows another in a regular pattern as the flock moves from shrub to shrub. Nests are finely woven pouches suspended from branches, seven to 12 inches long, made from grasses, leaves, and twigs, lined with spider webs and feathers. The call is a high-pitched twitter.

Bewick's Wren

The versatile and adaptable Bewick's Wren (Thryomanes bewickii, family Certhiidae) is found all over California and the other Pacific coast states, and across the southern United States, wherever there is dense shrubby vegetation with openings, such as chaparral and thickly landscaped backyards. This bird is about five inches long, gray brown on its back and paler underneath, with a white stripe above the eye and a long, thin, pointed bill that curves slightly downward. It frequently cocks its barred tail upward, and it switches it from side to side, rather than cocking it straight up like other wrens. In chaparral it forages within bushes, feeding almost exclusively on insects. Nests are found in a variety of places, usually cavities, and the highly complex song seems to vary between individuals.

California Quail

The California Quail (Callipepla californica, family Odontophoridae) is an easily recognized, plump, gray and brown bird about 11 inches long with a black, teardrop-shaped plume on top of its head. The male is boldly patterned in black, white, and earth tones with scallops and streaks. This bird is found throughout California and all along the Pacific coast from Canada to Mexico. The California Quail requires broken chaparral, with substantial and well-distributed openings between shrubs. It feeds in a style similar to chickens, pecking here and there on the open ground. It eats small seeds and tender plants in the openings between shrubs and uses the shrubs for cover and for roosting at night. The distribution of California Quail in chaparral is very uneven. Where there are sufficient openings, and where drinking water is available in the warm months, they are likely to be present. Where either of these resources is lacking, they are unlikely to be present. California Quail are always found in groups, called coveys, varying in size from one or two families of 10 to 20 individuals to as many as 200 birds. They much prefer to walk and run between shrubs when startled, but sometimes when a human or a predator draws near they will all take sudden flight, erupting with a startling whir of short wings, and then quickly dropping back down to safety a short distance away. They spend their entire lives within a small area, and they are unwilling to cross large openings to reach other patches of chaparral. Nests are built by monogamous pairs in small, lined depressions in the ground, concealed by vegetation, rocks, or other low-lying objects. While feeding they make low clucking sounds to stay together, so it is easy to tell when they are nearby, even though they are unseen. Their three-note call has the cadence of “ka-ka'-go,” with the accent and a higher pitch on the middle note.

Western Scrub-Jay and Steller's Jay

Well named for its habitat, the Western Scrub-Jay (Aphelocoma californica, family Corvidae) inhabits dense vegetation wherever it is found. This includes the chaparral as well as other habitats such as riverside thickets and suburban backyards. This bird is noticed by everyone because it is noisy, relatively bold, and gregarious. It is just under a foot long, colored blue and blue black on the head and back, with ashy gray underparts and a thick, pointed bill (fig. 47). It is found in California, Oregon, and interior parts of the West in places with shrubby habitat, especially oaks. Omnivorous, it eats seeds, insects, carrion, lizards, small snakes and mammals, eggs and nestlings of other birds, and the odd French fry or other meal leftover. This is one of the few birds that can consume caterpillars covered with toxic, defensive hairs. It rubs the caterpillar in the sand, giving it a “haircut” before eating it. Western Scrub-Jays have been observed perching on the backs of cattle to pick off ticks and other parasites. Often miscalled a “blue jay” because it is blue and a jay, the Western Scrub-Jay is, however, a strictly western bird while the true Blue Jay (Cyanocitta cristata) occurs only east of the Rocky Mountains. At the upper margins of chaparral, where conifers appear, Western Scrub-Jays are replaced by the equally noisy and conspicuous Steller's Jay (Cyanocitta stelleri, family Corvidae), a much bluer bird with a black crest. In places where pines and chaparral are intermixed, the two jay species can occur within earshot of one another. The Western Scrub-Jay call is a hoarse, single-syllabled, drawn-out rasp that rises toward the end, like a question, often repeated and echoed by other members of the flock. Nests are built in dense foliage, often near water.

Figure 47. A Western Scrub-Jay on a toyon branch. It is the only bird of its size in chaparral that is conspicuously blue on the outer wing, cap, and tail, shown here as dark gray.

Western Scrub-Jays live in small flocks of genetically related birds. They have highly organized social behavior that is most obviously manifested in their constant calling to one another. They will raid the acorn caches of other species of birds and take over backyard bird feeders by driving other birds away. They will collectively scold any intruder, human or otherwise, who is perceived to be threatening the welfare of any member of the group. Western Scrub-Jays, like their cousins, crows and magpies, are inquisitive and have intelligence reflected in quick learning and flexible behavior.

An example of their inquisitive behavior and intelligence comes from first-hand experience. In my (R.Q.) chaparral study site I set live traps for rodents, baited with seeds and peanut butter and arrayed in a regular checkerboard pattern. A flock of Western Scrub-Jays discovered that I was placing food in these traps in the late afternoon and quickly learned to follow along behind me, robbing each trap of its bait, and in the process springing the traps so that they were useless for my purpose. I tried changing my routine, setting traps at various times of the day, skipping several days, and setting them in different sequences, but to no avail. The birds were was always right behind me, calling to one another and, it seemed at the time, taunting me. Eventually, I had to resort to setting traps in the deepening dusk, with a headlamp, after the noisy and clever jays had retired for the night. One day one of these raiders was accidentally caught by one leg in one of the traps, uninjured but indignant. As I gingerly released it, trying to avoid injury to its leg, and to my hands from its vigorous pecking, several members of its flock perched just above my head, vociferously squawking about my treatment of their flock mate. If birds know how to curse, that is surely what they were doing.

Anna's Hummingbird

Anna's Hummingbird (Calypte anna, family Trochilidae) is the most common species of hummingbird found in chaparral, although several other species may be seen occasionally, especially during spring and late summer migration. It is found all year in the chaparral of both northern and southern California. Its original range is thought to have been the Pacific Slope of California from the Bay Area to Baja California, but that range has been extended northward to Canada and into southern Arizona and New Mexico. The adult male can be recognized by the iridescent magenta that covers the entire head. Like all the California hummingbirds it is quite small, three to four inches long, with a long, needlelike bill for probing flowers. In addition to feeding on nectar, Anna's hummingbird consumes more insects than the other North American hummingbirds, taking insects from the air like a flycatcher and also picking them off foliage while hovering. Anna's Hummingbird is among the first birds to breed each year in chaparral, beginning as early as late November and continuing through April. The tiny cup-shaped nests are lined with silk from spider's webs, and these nests may sometimes be found hidden in the dense branches of chaparral shrubs. The nearly year-round flowering of some native plant species, such as California fucshia (Epilobium canum), and the early flowering of others, such as the golden currant (Ribes aureum) and fuchsia-flowered gooseberry (Ribes speciosum) (pl. 47) in canyons and at lower elevations, provide a natural source of nectar at all times of the year. It is hypothesized that the early breeding of Anna's Hummingbird in California developed in conjunction with these native plants. In and around urban areas these natural sources of food are strongly supplemented by ornamental plants and, of course, hummingbird feeders. This new, reliable, and widespread food is thought to be the cause of this species' recent range expansion. The male song is a loud and very distinctive high, rolling rasp with a mixture of equally high squeaks and little chirps.

Hawks (Order Falconiformes)

Hawks and owls are associated with the edges and openings in chaparral, especially where it borders woodlands and canyons that provide trees for roosting and nesting. Since these birds find food visually or by hearing, dense chaparral is not a place where they can easily hunt. They are more commonly seen flying above open, burned chaparral, where small mammal and large insect prey are common and relatively exposed, and along the edges between chaparral and more open plant communities. The most common hawks (family Accipitridae) associated with the chaparral are the Red-tailed (Buteo jamaicensis), the Cooper's (Accipiter cooperii), and the Sharp-shinned (A. striatus). All three of these species have broad ranges that include most of North America.

Figure 48. A Red-tailed Hawk in flight. The dark belly band, in line with the center of the wings, is a useful field mark. The shading of the underside of the wing as seen in flight is variable, but the front of the wing is usually darker than the rest of the wing.

Red-tailed Hawk

The Red-tailed Hawk is often seen circling above chaparral looking for rodents, snakes, and rabbits in openings, and perched upon vantage points such as telephone poles and trees in search of rabbits, wood rats, pocket gophers, and other potential prey. When observed flying high overhead, the hawk is generally traveling, not hunting. This stout-bodied raptor is recognized in the air by its broad, rounded wings, four feet across, usually with a dark bar or wedge on the underside of the leading edge (fig. 48). The body plumage of the underparts varies from dark to light streaky brown, but the head is always dark. Despite this bird's name, the tail is not always red. An immature bird has a banded gray tail, and the red on the tail of a flying adult is only easily seen when the hawk banks and the upper surface of the tail becomes visible. Soaring hawks like the Red-tailed find their prey with keen vision. One of the major items of the Red-tailed Hawk diet in chaparral is the wood rat (Neotoma spp.), which although typically nocturnal, sometimes emerges from the nest at dusk. A Redtailed Hawk that captures a wood rat must concentrate its attention on these abundant but elusive rodents during the passing interval of dusk, perhaps snatching one off the top of its nest or from an exposed branch. Red-tails have an unusually long breeding season, beginning in late winter and extending into summer. They build large, conspicuous nests on the tops of trees, telephone poles, and other places with unobstructed access from the top and a clear view in all directions. The nests, which may be as much as two feet across, are made mostly from large sticks. The call is a loud, descending “keeeeeeer” with a hissing undertone that can be heard over considerable distances.

Cooper's Hawk and Sharp-shinned Hawk

The Cooper's Hawk and its smaller cousin, the Sharp-shinned Hawk, are slimmer and smaller than the Red-tailed, with short, rounded wings and long, banded tails. This body design gives them the maneuverability and speed to pursue and capture small birds such as the Bushtit between the chaparral shrubs. They fly quickly through the bushes, snatching birds out of the air and off perches. They are widely distributed in California and the rest of the United States. Around chaparral they are most likely to be seen in woodlands, silently flying away from the observer, straight through the branches of trees, or gliding just over the tops of the shrubs while watching for a careless bird. The Cooper's Hawk is about the size of a crow, with a slender body 14 to 20 inches long and a wingspan of 27 to 29 inches. It has a long, banded tail, rounded at its tip. The Sharp-shinned Hawk is the smaller of the two, with a body 10 to 14 inches long and wings that are 20 to 28 inches across. The tail is proportionally shorter than that of a Cooper's Hawk and is squared off or notched at the tip. Both species have gray brown backs and a lighter breast mottled with brown or red, a color pattern that allows them to blend in well with the light- and dark-speckled environment beneath trees and between shrubs. Although both species prefer small birds, and can empty a bird feeder in seconds as finches and towhees scatter in fear, they also take small mammals, reptiles, and even large insects. Birds are plucked, and mammals skinned, before they are consumed. They conceal nests in trees, which are defended fiercely even from a human passing nearby. The Sharp-shinned calls with a rapid series of high rasping squeaks, while the Cooper's call is similar but lower pitched.

Owls (Order Strigiformes)

The Great-horned Owl (Bubo virginianus), Western Screech Owl (Otus kennecottii), and some smaller species of owls with broad distributions are also found peripherally associated with chaparral. Since these owls require openings between shrubs to hunt, they are uncommon in mature chaparral. Like the hawks, the first few years after fire when rodents are plentiful and relatively exposed, owls will be more abundant. The surest way to know whether owls are present, and which ones, is to listen at night for their distinctive calls. This is best done in late winter to early spring when they are about to breed and are calling to proclaim breeding territories. Calls can be heard over considerable distances, and in chaparral might come from nest sites or high perches in nearby woodlands.

Reptiles

Snakes and lizards are important to the overall well-being of chaparral communities statewide. These animals keep the populations of seed-eating rodents in check and also keep insect populations under control. They are an important food item for some predators, and indeed some snakes and lizards eat other reptiles. These complex interactions help to balance numbers of plants, herbivores, and carnivores in chaparral, thus assuring stability and continuity of the community. There may be as many as a dozen species of reptiles in a given area of chaparral, more than in the majority of other ecological communities of the state. These snakes and lizards typically have wide habitat preferences. Rattlesnakes, Gopher Snake, Western Fence Lizard, Side-blotched Lizard and occasional alligator lizards are among these widespread species. Two reptiles closely adapted to chaparral are the California Whipsnake and the Coast Horned Lizard. Most species are seldom seen because they are nocturnal and secretive, or are inactive when humans are most likely to visit. In addition to the snake species described below, about a dozen additional species of snakes are known to occur in chaparral. These are rarely seen, either because they are actually scarce in chaparral or because their habits and habitats make it unlikely that anyone, other than a determined herpetologist, would find them. In chaparral most of these elusive species occur only in southern California.

Snakes (Order Squamata, Suborder Serpentes)

Western Rattlesnake and Red Diamond Rattlesnake

For many people exploring chaparral, the first reptile that comes to mind is the rattlesnake. The Western Rattlesnake (Crotalus viridis, family Viperidae) is a ubiquitous inhabitant of chaparral and most other natural environments of California west of the deserts. The surest way to recognize this animal is the broad triangular head that is wider at its base than at the neck and of course, the rattles at the tip of the tail (fig. 49). This snake can grow to lengths of as much as five feet, although 1.5 to three feet is more common, with the young barely a half foot long. Contrary to popular legend, the number of rattles does not correspond to the age in years of any rattlesnake. Additional rattles are added whenever the snake sheds it skin. Shedding occurs as the snake grows, and that can happen several times in a year. The color of the Western Rattlesnake varies considerably from place to place, with mottles of brown, greenish colors, and black superimposed on an overall color that often is grayish. The Western Rattlesnake is active during the day or night, depending on the temperature, hunting small rodents such as kangaroo rats (Dipodomys spp.) and white-footed mice (Peromyscus spp.). This snake patrols a home area, following animal scent trails and curling up and waiting in places where prey is likely to pass by. It detects the location of potential prey from body heat, which it accomplishes by means of special sensory organs located in pits between the nostril and eye. The heat pattern allows it to accurately strike at prey, injecting venom that quickly paralyzes and kills the animal. The Western Rattlesnake is most active from April to October and hibernates during most of the rest of the year.

Figure 49. A Western Rattlesnake shown coiled in resting position. If the snake were alarmed the head would be raised higher and pulled back over the center of the coil, and the tail rattle would be turned up vertically.

The beautiful Red Diamond Rattlesnake (Crotalus exsul) inhabits chaparral and other brushy habitats in the Peninsular Ranges of southern California from Orange and Riverside Counties southward. It has the same general body size and shape as the Western Rattlesnake, but as the name implies, it has a diamond pattern on the back and is reddish or tan in coloration overall, with pronounced dark and light rings on the tail.

The most important thing to remember about rattlesnakes encountered in chaparral is that they have a retiring disposition and, when given a choice, will avoid or move away from contact with humans. If a person or any other large animal draws too near, a rattlesnake will begin to rattle by vibrating its tail. This sound is a warning, designed to ward off an approaching animal. Heed this warning! If you hear a rattling snake, freeze immediately until you determine the location of the sound, and then slowly move away from the source. It is best, when moving through chaparral or any other dense vegetation, to watch where you step and to move slowly enough to give a startled rattlesnake time to raise a warning before you draw too near. In chaparral there is little cause for concern in the cooler months, when rattlesnakes are hibernating.

California Whipsnake

The California Whipsnake (Masticophis lateralis, family Colubridae), also known as the Striped Racer, has been called the “chaparral snake”because it is so characteristic of this habitat. Its range almost exactly coincides with that of chaparral. It frequents the rocks and bushes of the chaparral, eating a variety of small mammals, lizards, other snakes, birds, and insects. It is a slender snake that grows up to five feet long, brownish or black on its back, with a yellow or white stripe on each side (fig. 50). The California Whipsnake is well adapted to the chaparral habitat. In addition to foraging on the ground, it also spends much of its time in the shrubs basking on the upper branches, hunting for eggs and other prey among the stems, and seeking shelter in the larger branches. While hunting it holds its streamlined head above its body. The constant head motion and prominent eyes give this reptile a very alert appearance. It is efficient at exploring burrows and other hiding places of its prey. As shown in pl. 67, it seizes live prey, which it holds in its powerful jaws until it stops struggling, and then swallows.

Figure 50. A California Whipsnake in hunting posture. Note the slender body and head, and the light stripe along the flanks.

Temperature regulation is exceptionally well developed in the California Whipsnake, which is one reason it is so successful in chaparral. It is active from March to October and then hibernates until spring. This snake is often noticed because it is active during the heat of the day and moves about quite quickly beneath chaparral shrubs, as the name “racer” implies. It is too nimble to be easily captured and can deliver a harmless bite—so quickly that the pursuer may be unaware for a time that it has been bitten. Sometimes this snake emits a musky smell when handled.

Plate 67. A California Whipsnake swallowing a Western Fence Lizard. The snake temporarily unhinges its jaw so that the lizard can pass through its throat into the digestive tract. This leaves a food bulge in the snake's body that gradually shrinks and moves toward the rear as the lizard is digested.

California Whipsnakes mate in late spring and lay eggs about a month later. The eggs hatch in October or November. Small snakes heat and cool more rapidly than their larger parents, so the hatchlings can continue to be active on warm days later into fall than can the adult snakes. They depend on getting a good store of food into them before winter cold stops their feeding. Perhaps it is this active period early in their lives that allows them to grow particularly rapidly. One-year-old snakes are 12 to 18 inches long, and that length is doubled by the time a snake is two years old. After two years, growth is slower. It is difficult to determine the ages of adult snakes, but they are thought to live to about five or six years.

Gopher Snake

The Gopher Snake (Pituophis catenifer, family Colubridae) is a large, light to medium brown, heavy-bodied snake common in many habitats across the western United States. It occurs occasionally in the chaparral, where it frequents openings between shrubs. It can grow up to six feet long, although it is ordinarily about half that size, and is a yellowish or creamy color with blotches of brown, black, or reddish brown on the back. The large size and daytime habits make this an easily noticed animal. When a Gopher Snake is disturbed it will flatten its body, hiss, and vibrate its tail. Despite these theatrics, it is harmless and relatively docile. A Gopher Snake will come out onto paths and roads for warmth. In this conspicuous location, the diamondlike pattern of blotches on the back and its habit of tail-shaking when disturbed sometimes cause it to be mistaken for a rattlesnake. This reptile is beneficial in its natural habitat and around homes because it controls rodent pests, as is implied by its name, and so it is best left alone. In spite of its large size, a Gopher Snake can climb, but its preferred method of hunting is to crawl down burrows and corner rodents. It kills larger prey by constriction but may simply swallow smaller animals. It hibernates below ground in the colder months, breeds in spring, and lays eggs in early summer, which hatch later that same season. Newly hatched Gopher Snakes are about a foot long.

Western Patch-nosed Snake

The Western Patch-nosed Snake (Salvadora hexalepis, family Colubridae) is widespread in the deserts and chaparral of southern California but is not often encountered. Typically about three feet long, it has a slender body with dark sides and a broad yellow or tan stripe down the back. It derives its name from an enlarged scale that folds up and back across the tip of the snout, just above the mouth. Presumably this scale assists the animal in burrowing and pushing under rocks. Like the California Whipsnake it moves quickly, is day-active, and preys on lizards, buried eggs, and small mammals in their burrows. It will also climb in search of bird nests. It remains active whenever there are warm days. Eggs are laid in early summer, with hatchlings just under a foot long emerging in late summer.

Lizards (Order Squamata, Suborder Lacertilia)

As with snakes, few species of lizards are restricted to the chaparral. Most are found in a variety of other open and brushy habitats across the state. The most nearly chaparral-specific are the Coast Horned Lizard and the Western Whiptail. Other common chaparral lizards in the family Phrynosomatidae are the ubiquitous Western Fence Lizard, the Sagebrush Lizard, and the Side-blotched Lizard, as well as the Southern Alligator Lizard (family Anguidae).

Coast Horned Lizard

The Coast Horned Lizard (Phrynosoma coronatum, family Phrynosomatidae), also sometimes called Horny Toad, is characteristic of the chaparral and adjacent communities from northern California through Baja California. It prefers sandy soil in which it can dig down for shelter. Its dragonlike appearance is unmistakable, with a row of sharp horns at the back of the head, a round, flattened body, spiny scales along the back and tail, and two rows of smaller spines on each side of the body (fig. 51). The head and body are 2.5 to four inches long. This lizard feeds mainly on native harvester ants (Pogonomyrmex spp.), supplemented by other insects. The harvester ants in turn depend on the seeds of chaparral and other native plants for their food. These feeding relationships link the survival of the plants and animals. The Coast Horned Lizard is classified as a Species of Special Concern by the California Department of Fish and Game and the U.S. Fish and Wildlife Service. It has disappeared from most of the lower-elevation portions of its original range due to habitat loss, and quite possibly the disappearance of harvester ants, which have been exterminated in many places by the aggressive, exotic Argentine Ant (Linepithema humile). The Coast Horned Lizard does not eat Argentine Ants. This loss of food could be further aggravated by the recent arrival in coastal California of another aggressive, imported species, the Fire Ant (Solenopsis invicta). Given these losses and displacements, remaining habitat for the Coast Horned Lizard in chaparral would be in places away from urban and agricultural disturbance, the exotic Argentine Ant that often accompanies human activities, and marauding house cats.

Figure 51. The Coast Horned Lizard, increasingly rare in chaparral near populated areas, is the only horned lizard of chaparral.

The Coast Horned Lizard utilizes open areas between shrubs, which is where harvester ants are likely to be found, and sandy soils in which it can bury itself. In chaparral such openings are commonly near the bottoms of washes, along roads, and on uneven terrain. It spends the hottest parts of the day and much of the late afternoon and evening buried from one to several inches underground, where the soil is cooler and moister than on the surface. The Coast Horned Lizard hunts by situating itself near an ant nest or trail and waiting for ants to walk by. As ants parade past an effective tongue flip dispatches them quickly and quietly. This method is efficient, as it limits energy spent on hunting. A small lizard requires only about one-thirtieth of the food needed by a small bird of the same size. This lizard is most active between April and August, which is the time of year when harvester ants, its preferred food, are out and about.

Coast Horned Lizards lay eggs in late June. The young hatch in September and forage for a period of time in the early fall. Adults become largely inactive after egg laying, and remain in burrows or buried in the soil during the hottest part of summer. This inactive state during the summer heat gradually grades into winter hibernation, from which they emerge in early spring.

One of the most interesting adaptations of the Coast Horned Lizard to life in the open in a sunny climate is an internal sunscreen. To prevent damaging ultraviolet light from reaching the internal organs, which are just a few tenths of an inch below the skin, the lizard's peritoneum, the membrane lining the body cavity, is heavily pigmented. This membrane is almost black and thus screens out the light. This unusual color adaptation in the peritoneum is in marked contrast to most other animals, including humans, where the membrane is a bright pink. The darkly pigmented lining functions like internal “sunglasses.”

Because Coast Horned Lizards spend much of their time in the open, they are a likely meal for more active predators such as snakes, other lizards, or birds of prey. If approached, the lizard will tend to freeze, relying on protective coloration to avoid detection. If a Coast Horned Lizard is lightly touched, it can scurry away to safety as quickly as any other lizard. If protective coloration or flight does not suffice, this lizard has other options. Some of these are mechanical, such as its spines, while others are behavioral such as rising up to look larger, but the most unusual involves shooting blood at its pursuer!

When a dog, coyote, fox, or persistent human closely approaches a Coast Horned Lizard, it may turn to a chemical defense. It can use blood vessels and sinuses in its head to increase blood pressure around the eyes, building it up until blood is forced out the tear duct from between the closed eyelids. The dog, fox, or coyote luckless enough to annoy the lizard at this moment is then forcibly sprayed with fine jets of blood, which they find quite repulsive. It is not known why doglike predators find the blood so distasteful, but the reactions of the unlucky canines make obvious that it is very unpleasant. The Coast Horned Lizard can perform this defensive blood squirting several times if hard pressed. This treatment usually deters the offending predator.

Western Whiptail

The Western Whiptail (Cnemidophorus tigris, family Teiidae) is a very common lizard in chaparral as well as in other habitats across the state. It is slender, with a pointed snout and a tail about twice as long as the 2.4 to five inch head and body (fig. 52). The back is reddish brown with dark blotches and as many as eight light stripes, sometimes indistinctly defined. It has long hind legs and toes and drags its tail as it scurries from place to place. It is often heard before it is seen, scuttling through dry leaves. The Western Whiptail has a fidgety manner about it and can be recognized by its constant, jittery movements as it forages for invertebrates in the leaf litter. This lizard is active all day in chaparral even when the weather is quite hot, constantly twitching its head from side to side. It is the principal food item of the California Whipsnake (pl. 67), and the two are active throughout the day. Eggs are laid in late spring, and both adults and young enter hibernation in late fall to early winter.

Figure 52. A Western Whiptail, with a small California poppy plant in the background. Constant motion makes this lizard easy to detect, and the long tail makes it easy to identify.

Western Fence Lizard and Sagebrush Lizard

The Western Fence Lizard (Sceloporus occidentalis, family Phrynosomatidae) is one of the most numerous and widespread species of reptile in California, found everywhere except deserts and mountains above 6,000 feet. It has a brown, black, or light gray back, with blue along the sides of the belly, and is about six inches long including the tail (fig. 53). In spring the throat and belly patches of the male become a brilliant blue, and the male displays as much color as possible to other lizards by doing pushups while distending its throat. Viewed in profile, which is the perspective of another male lizard, this posturing emphasizes the size and blueness of the posturing male. This lizard's name is derived from its habit of using vertical wood, rock, or masonry surfaces for sunning, so that near human habitations you can see it often on fences, walls, and wooden posts. In mature chaparral, it is most often found around openings in the shrubs, and other places where the sun reaches the ground (pl. 31). It can be found out and about on any warm and sunny day, even in winter. The Western Fence Lizard forages for all sorts of invertebrates on the ground, rock surfaces, and branches. The high perches selected for foraging, and for territorial displays by males, make it easy prey for snakes and hawks. Breeding occurs in spring, and six to 15 eggs, one-quarter to one-half inch long, are laid in moist soil. The young hatch from mid- to late summer.

Figure 53. A Western Fence Lizard on a burned chaparral shrub stem. A very common lizard in sunny places within and around chaparral.

It has been recently discovered that Western Fence Lizards reduce the incidence of Lyme disease. When the tick that carries the disease bites these lizards, apparently, the disease-causing bacterium within the ticks is killed. The lizards seem to be immune to the disease, and this immunity is transferred to ticks along with the lizard's blood. About five percent of ticks living in areas with Western Fence Lizards carry Lyme disease, while 50 percent carry the disease in places without these lizards. No one would have guessed that a lizard would have anything to do with this disease.

The Western Fence Lizard can survive chaparral wildfires by staying below ground, after which they are often seen sitting out on the ends of burned branches. The Sagebrush Lizard (Sceloporus graciosus, family Phrynosomatidae) is a similar but slightly smaller animal that occupies chaparral at elevations above 5,000 feet. This is primarily a mountain animal, ranging up into pine forests, but at intermediate elevations the ranges of Sagebrush and Western Fence Lizards overlap.

Side-blotched Lizard

The Side-blotched lizard (Uta stansburiana, family Phrynosomatidae) is a very common small lizard of open chaparral as well as many other habitats in central and southern California. The head and body are about 2.3 inches long, and the tail is somewhat longer. It has a dark blotch just behind the front leg on both sides, a mark that makes it relatively easy to identify and provides its common name. The male often has a lot of yellow to orange on the sides of the head and body, and blue speckling on the back. In chaparral it is most common in openings where the vegetation has recently burned or otherwise been disturbed, and on very steep, rocky slopes. It is absent from dense chaparral. Active all year in most places, it pursues a variety of invertebrates taken from the ground, rocks, and lower branches of shrubs. Breeding and egg laying take place from spring to late summer, and a female may produce several clutches in a single season.

Southern Alligator Lizard and Northern Alligator Lizard

The Southern Alligator Lizard (Elgaria multicarinata, family Anguidae) and Northern Alligator Lizard (E. coeruleus) are slender, long-bodied animals with a head and body up to six to seven inches long, and a tail that can be twice that long. They have a glossy look due to smooth scales. A large triangular head together with small legs gives them a snakelike appearance. These Alligator Lizards are reddish to gray brown, with dark stripes across the back. They are found everywhere in the state except the deserts and high mountains. The northern species is slightly smaller than the southern, but the two are difficult to tell apart without close inspection of the scales. This is not recommended, because when handled they will invariably turn and deliver a painful bite with their surprisingly powerful jaws. The range of the two species overlaps both along the central coast and in the foothills of the Central Sierra Nevada. They prefer relatively dense cover, so that in and around chaparral they would be most often encountered in weedy vegetation, and in places with an accumulation of leafy litter, logs, or other objects under which they can hide. They eat insects, small rodents, birds, and even other lizards. They climb quite well, using their tail for grasping and balance, and sometimes nest in the crotches of trees that have accumulated leaves and twigs. Both are common residents around houses and frequently found in backyards, particularly if a pool of water is present. Breeding takes place in late spring, eggs are laid in midsummer, and eggs hatch about two months later, producing young no more than three inches long.

Amphibians

Chaparral is generally considered too dry for amphibians. Since they require moisture for reproduction, adjacent habitats such as oak woodlands and watered canyons contain more species and more individuals. The lack of moisture in chaparral is especially limiting in southern California, where damp environments are fewer and farther between than they are in the north. In chaparral the best time to search for amphibians is on temperate winter or spring nights during rain, especially in canyons and other places not too distant from water. During the drier part of the year amphibians retreat to cool, moist refugia such as wood rat nests or migrate to places that have damp soil and litter, such as watered canyons. The most likely amphibians to be encountered in chaparral are the Ensatina Salamander and the Western Toad.

Ensatina Salamander (Order Caudata)

The Ensatina Salamander (Ensatina eschscholtzi, family Plethodontidae) is sometimes found in chaparral, although it is more commonly associated with redwood forests and other coniferous forests of northern and central California. The head and body range from two to three inches in length, plus a thick tail that is constricted at its base (fig. 54). The color varies greatly from place to place but is generally dark with yellow, orange, or pink spots that may fuse together to various degrees. The smooth skin must remain relatively moist, because the Ensatina lacks lungs and must breathe through its skin. In chaparral it is only during the rainy periods that it can move freely about, foraging for various invertebrates and snails. Mesic and northerly preferences notwithstanding, this animal inhabits chaparral even in southern California. One reason this salamander is able to inhabit chaparral is that it does not reproduce in water, laying eggs in moist places or in surface litter during the rainy season. The young hatch as small adults. This trait is shared with a number of other species of California salamanders, which sets them apart from other North American amphibians that lay eggs in water. Ensatinas take several years to reach sexual maturity and live as long as 15 years.

Figure 54. An Ensatina Salamander in damp leaf litter with miner's lettuce (Claytonia perfoliata) in the background. Look for this animal in cool, wet weather.

Western Toad (Order Anura)

The Western Toad (Bufo boreas, family Bufonidae) is found almost everywhere in California west of the deserts. The body is 2.5 to five inches long and colored grayish to greenish, with the warts set upon blotches that are dark and often rusty colored. A cream-colored stripe runs down the middle of the back, from between the eyes to the rump. The Western Toad tends to walk rather than hop. Unlike the Ensatina Salamander, this animal is bound to water for reproduction, so it can probably venture no farther into chaparral than the distance it can travel from the nearest body of surface water. At the extreme this commute may be about 1.2 miles in each direction. It doubtless retreats below ground into rodent burrows and other moist recesses during the long summer stretches of warm, dry weather.

Insects and Arachnids

Insects and their relatives (spiders, mites, ticks, and scorpions) show some of the most specialized adaptations within the chaparral community. Adaptations are traits that allow an organism to live successfully in its particular environment. These adaptations can be physical, physiological, or behavioral. Others are inextricably linked with plants for their reproduction and survival. Below are some interesting examples of adaptations to living in chaparral. Other insects are discussed in chapters 2 and 3, and earlier in this chapter under Wood Rats. Much more remains to be learned about these numerous and important organisms, so this is but a small selection of accounts about some better-known species.

Insects (Class Insecta)

Harvester Ants (Order Hymenoptera)

Ants are among the most obvious ground dwelling insects of the chaparral. A survey at four chaparral sites found 45 different kinds of ants, about one fifth of all the ants known in California. One of the best-known and conspicuous ants in the chaparral are the harvester ants (Pogonomyrmex spp., family Formicidae). These ants have conspicuous nests in clearings between shrubs in mature chaparral and upon the blackened soil in burned chaparral. Harvester ant nests typically have a cleared area up to a yard wide around the nest entrance, with a ring of chaff at the outer edge. The ants themselves can be up to one-quarter inch long and are bright red with conspicuous bristles on the legs and abdomen (fig. 55). While they are not extremely aggressive, disturbing a nest will produce a swarm of stinging, biting ants, and these bites and stings can be quite uncomfortable for several days. They have the habit of crawling up human legs and stinging wherever they get stuck, so it is unwise to stand still for long where harvester ants are busy.

Harvester ants eat seeds of chaparral plants. A foraging worker ant will travel 100 feet or more from the nest to find food. They search for seeds during the day using vision, so they are most active in the mornings and afternoons, frequently staying underground during the hottest part of the day. As described earlier in this chapter, the Coast Horned Lizard (Phrynosoma coronatum), their principal predator, also hunts at the same time. Harvester ants patrol the ground around fruiting shrubs and, in some cases, seem to pick up seeds the moment they fall upon the ground. Once a worker has a seed it returns to the nest site to shuck it. The ants leave the chaff outside the nest, forming a conspicuous ring of hulls, and take the cleaned seeds into the nest. As illustrated in fig. 55, harvester ants will grasp surprisingly large seeds, sometimes as big as the ant's head. They can do this because of the wide gape of their jaws and muscles that work the jaws like an exceptionally strong pair of tongs. When the ants bring seeds into their nests, they are not only provisioning themselves, but they are also incidentally protecting seeds from decay and from being eaten by other organisms. Some seeds may remain in the underground storage chambers until the next fire, and be in a very good place to germinate and grow when rain falls on the burned area.

Figure 55. A harvester ant carrying a ceanothus seed by grasping it between its jaws.

Harvester ants are not active in winter, so the nest entrances usually remain closed during that time, but the nests are still readily identified by the circle of cleared ground with a ring of discarded material around the outside. Their nest sites require the warmth provided by direct sunlight, so they are excluded from places where chaparral shrubs shade the soil.

Harvester ants are particularly abundant after fire, in response to the greater number of seeds available from the fire annuals that flower so abundantly then, and the expanses of unshaded soil created by the fire. Some fire-following plants, such as the bush poppy (Dendromecon rigida) (see chapter 4), have a special relationship with harvester ants. The bush poppy produces seeds with structures called elaiosomes attached to them. The elaiosome is an oil- and nutrient-rich structure providing immediate energy for the ants. The ants carry the seeds back to the nest using the elaiosome as a handle, and they receive a food reward for this activity. The ants typically remove the elaiosome first and tend to the seed later. This is a mutually beneficial relationship between ant and plant since the elaiosome feeds the ant, which in return disperses bush poppy seeds away from their point of origin. This is a common arrangement between ants and plants in the shrublands of South Africa and Australia, but it seems to be unusual for chaparral. The large carpenter ants (Camponotus spp.) also move seeds about in chaparral, but these ants are found in mature chaparral, where they are more difficult to detect.

Antlions (Order Neuroptera)

The bodies of chaparral ants are a good source of water and nutrition, so they are the chief food items of the Coast Horned Lizard (Phrynosoma coronatum) and also of the larvae of a predatory insect called an antlion (Myrmeleon spp., family Myrmeleontidae).An antlion, often called a doodle bug, is actually the larva of a beautiful winged insect that resembles a small mayfly or damsel fly. The adult antlion's only function in life is to reproduce. It does not feed, but exists in a winged state for the short-lived courtship flight and mating. The feeding stage is the larva, which is a voracious predator. The antlion larva makes a trap with its paddle-shaped head, which is specially shaped for digging and flipping sand. It catches and dispatches its prey with a pair of powerful hooked jaws.

Antlions are found where the soil is fine textured and dry. The antlion makes a cone-shaped depression with the sides sloped at a precise angle such that tiny soil particles or sand grains will slide downward at the slightest disturbance. Once an ant or other insect steps on the edge of the pit, the disturbed grains begin to slide toward the bottom. With each step more soil slides down the sides, carrying the hapless insect ever deeper in the pit. The antlion, meanwhile, actually throws sand at the struggling victim, causing a yet greater cascade down the sides. At the bottom of the trap, the waiting antlion larva seizes its meal with dispatch. Once the larva is full grown it spins a cocoon underground, goes though pupation, and emerges as a pale, diaphanous, night-flying adult. By the end of its one evening of courtship, eggs are laid and a new generation of antlions begins its development.

Gall Wasps (Order Hymenoptera)

Members of the gall wasp family (Cynipidae) use plants to provide food and shelter for their larvae. Oaks in particular are a favored host for these wasps. They deposit their eggs in plant stems and leaves after piercing the plant surface. Chemicals associated with the eggs, and later with the larva, cause the affected part of the plant to gradually enlarge to form a structure called a gall, within which the insect grows. The exact mechanism by which these chemicals stimulate the plant to produce abnormal growth is not fully understood. On oaks (Quercus spp.), the galls also contain protective chemicals called tannins, which likely serve to defend the developing gal! wasps as well as they defend the oak.

Of the galls found in the chaparral, oak “apples” are among the easiest to observe and are often seen on the stems of scrub oaks (pl. 68). As shown in pl. 68, they are sometimes quite red and larger than a golf ball and may exude a sticky sweet-tasting substance. The gall is filled with a spongy tissue that is rich with water and sugar from the plant, and this is what nourishes the larva within. If you cut a fresh gall open in summer you may find the small, cream-colored, wormlike larvae inside. In contrast, most galls on other chaparral plants are as insignificant in appearance as simple curls or bubbles on a leaf, or bumps on a stem.

Plate 68. A wasp gall growing from the stem of a scrub oak.

Gall wasps have some peculiar traits. For instance, one generation may have both males and females with wings, a rather natural thing for a wasp, but the next generation will be nothing but wingless females that have been produced asexually, meaning that the eggs hatch without fertilization by a male. Another oddity is that different species of wasps may sometimes share the same galls. This happens because some gall wasps lay their eggs in galls that have already been formed by other species of wasps. In the end, two different species of wasps will emerge. Galls are fascinating to observe. As is the case with many aspects of the biology of chaparral insects, they need much more study before they will be well understood.

Plate 69. A Red-haired Velvet Ant. The bright coloration advertises its presence as it moves on the ground.

Velvet Ants (Order Hymenoptera)

“Velvet ant” is the common name applied to a group of wasps (family Mutillidae) in which the females lack wings. They attract attention because they are fuzzy and brightly colored and are often seen scurrying over open soil around chaparral in late summer. Several species occur commonly in chaparral, including the Red-haired Velvet Ant (Dasymutilla coccineohirta), shown in pl. 69, and the White Velvet Ant (D. sackeni). They are about one-half and three-quarters inch long, respectively. The biology of velvet ants is not well understood, but they probably parasitize the larvae of ground-nesting bees and wasps. When seized, velvet ants make a characteristic squeaking noise. Do not use your fingers to grab a velvet ant because they have a very painful sting. In other parts of the country they are called cow-killer ants, and in Mexico hormigas del diablo (devil ants).

The Yucca Moth (Order Lepidoptera) and the Chaparral Yucca

One of the most interesting relationships between plants and insects in the chaparral is seen between the Yucca Moth (Tegeticula maculata, family Prodoxidae) and the chaparral yucca (Yucca whipplei). This pair has evolved together over a long period of time, and the survival of each is secure only if they work together. Yuccas are a bit of a conundrum to botanists, because we cannot age them and we do not know what causes them to flower, or prevents them from flowering. We observe, however, that when one chaparral yucca blooms, so usually do many others in an area, and this is particularly so after fire (pl. 9). A fire will sometimes stimulate yuccas to flower months out of the normal season of June. Yuccas and Yucca Moths are widespread in the western United States, but the chaparral yucca has its very own moth, found nowhere else, and that moth can survive only by rearing its young in this chaparral yucca plant. The yucca plant produces pollen that must be transferred from one flower to the next so that fertilization can occur and seeds produced. This is where the Yucca Moth comes in, because only the Yucca Moth can do the job for the yucca plant.

Normally, flower pollen is small and easily dislodged on insects as they fly or climb about the flower. Yucca pollen, however, is sticky and hard to remove from the anther, the male flower part that produces it. Yucca pollen comes loose as a series of sticky strands. From most insects' point of view, chaparral yucca pollen has all the properties of chewing gum on a hot sidewalk, a substance to be avoided. The female Yucca Moth, however, has just the right equipment to handle the sticky pollen. She has a specially curled tentacle that she uses to roll the pollen into a neat ball after scraping it from the anther. She then tucks it under her tentacle and flies off to the next yucca flower.

The reason for this effort is that the female Yucca Moth is preparing to supply her young with food. The young Yucca Moth larvae eat developing yucca seeds. So the female Yucca Moth must ensure that seeds will develop from the flower where she deposits her eggs. She first packs the sticky pollen onto the stigma, the top of the carpel, which is a female flower part. This act ensures pollination and fertilization of the flower. Once this step is completed, the female moth moves to the base of the carpel, nearest to the part of the flower where the seeds will develop following fertilization, and lays her eggs. Her long ovipositor pierces the wall of the carpel such that the eggs are placed in the same cavity where the seeds will develop. Once the eggs are safely tucked inside the carpel base near the seeds, the female Yucca Moth heads off to collect another ball of pollen. She will continue to lay eggs in different flowers for as long as she has eggs, a period that may be as short as a few days or as long as a week. Inside the carpels, the seeds start to grow and so, too, do the Yucca Moth larvae. In time the fully developed larvae are ready to form pupae, but to do so they must leave the enlarged carpel base, now called a capsule, which they do by tunneling through the capsule wall and dropping to the ground. The larvae burrow into the soil and remain there, slowly developing into adult moths for a year or more, until the yucca plants are again in bloom.

The Yucca Moth cannot complete its reproductive cycle without the chaparral yucca plant, and the chaparral yucca plant cannot reproduce without the Yucca Moth. This is a special example of what is called coevolution, where the biology of two species develops over time in such a way that each becomes adjusted to the other. The trick to this particular system is that not all the yucca seeds are eaten by the larvae because many more are produced than can be eaten. Pollination is made certain, and the plant pays the price of a few seeds to feed the moth larvae. Because of this special relationship, should anything happen to either species, the other would be doomed. Chaparral yuccas tend to flower simultaneously over large areas. That is why in certain years chaparral hillsides are thick with the conspicuous tall “candles” of yucca inflorescences. The mass flowering produces a favorable setting for the Yucca Moth reproduction and thus for the yucca plants too, but the mechanism for simultaneous flowering remains a mystery. Perhaps the moths themselves carry a signal to tell each generation of plants when to flower, or perhaps the plants produce a signal when the environment is favorable for moth reproduction.

After the yucca plant has flowered and died, it becomes host for a variety of insect species. The dried flowering stalk serves as the domicile for another insect, the California Carpenter Bee (Xylocopa californica, family Anthophoridae, order Hymenoptera). This huge, solitary, dark blue insect can be as much as an inch long. Despite the formidable appearance of this slow-flying bee, it is not aggressive. The female chews a tunnel into the stalk, where she lays about six eggs, each walled off in separate chambers made from sawdust chewings. The larvae feed on provisions of nectar and pollen brought to the nest by the female. The Black Yucca Weevil (Scyphophorus yuccae, family Curculionidae, order Coleoptera) bores as a larva into the basal stem of the dead yucca, and the adult feeds on stem sap. But most of the decomposition of dead yucca stalks is done by the Yucca Longhorn (Tragidion armatum, family Cerambycidae, order Coleoptera), a beautiful orange and black, one-and-one-half inch long beetle. The adult female feeds on the blossoms and stem sap of the flower stalk and then lays her eggs on the outside of the stem, so that the hatching larvae can bore into the drying fibers of the stalk. The larvae excavate long galleries through the pithy center of the stalks and may eat up to half of the lower stalk. Larvae pupate within these galleries and emerge as adults in late spring or summer in concert with the flowering of nearby yuccas.

Darkling Beetles (Order Coleoptera)

Darkling beetles are often seen late in the day ambling along paths in chaparral and oak woodlands. They belong to the genus Eleodes (family Tenebrionidae). There are approximately 100 species of darkling beetles in California, ranging in length from .4 to 1.5 inches, and it takes a specialist to tell one species from another. They have smooth, shiny black bodies with a pointed abdomen (pl. 70). These beetles are unable to fly, having traded flying wings for a fused upper body, thickened to protect it from the bites and pecks of predators, and well suited to retaining moisture in a dry environment. They are often noticed because of the peculiar habit of performing a headstand when disturbed. This maneuver is meant to display the tip of the abdomen, where a noxious defensive fluid is emitted, to deter potential predators. This behavior explains the origin of two other common names for darkling beetles: stink bugs and circus beetles. This method of defense is apparently so effective that it is mimicked by other species of beetles that have a similar appearance but do not exude defensive chemicals.

Plate 70. A darkling beetle performing a threatening headstand.

Plate 71. A tarantula hawk wasp sitting on flowers.

The Tarantula Hawk Wasp and the Tarantula Spider

Tarantula hawk wasps (Pepsis spp., family Pompilidae, order Hymenoptera) are good at coping with the scarcity of water and food in the chaparral. It is a very large wasp, a dark steely blue to black, and usually has contrasting orange red wings (pl. 71). It can be up to two inches long and is armed with a formidable stinger. The adult wasps actually eat only nectar; however, in order to provide for their young the adult females hunt the largest spider in the chaparral, tarantulas (Aphonopelma spp., family Theraphosidae, order Araneae). To the wasps the tarantulas represent a source of food and moisture for their young.

The life and death battle between tarantula hawk wasps and tarantulas is among the most dramatic struggles to be witnessed by a visitor to chaparral. A tarantula hawk wasp weighs less than .02 ounces, about the weight of a large paperclip. Tarantula spiders, on the other hand, are hundreds of times larger than the wasps (pl. 72) and outweigh them many times over. The wasps can maneuver much better than the bulky tarantulas, and they generally win by flying around a spider and stinging it several times on the underside. However, the wasps do not always win. The spiders have strong jaws and a most formidable defensive posture. An unwary wasp can be quickly dismembered. It seems an unlikely match, but the victory is never secure and each battle has its own outcome.

Plate 72. A female California Tarantula (Aphonopelma eutylenum). Despite its formidable appearance, this and other tarantulas of California are not dangerous to humans.

In those cases where the wasp is the victor it claims its prize with great effort. The wasp has stung the tarantula only enough to immobilize it so that she can bring it to her nest, a hole dug in the ground. This can be a lengthy process since it may be several hundred yards to the wasp's nest. To move the huge tarantula the wasp beats its wings furiously while using its jaws to grip the spider's leg or antenna. It then drags the spider along in a series of jerking steps. Once the spider is stuffed into the nest the wasp may sting it again, but still does not kill it. The spider is in a comalike state where its basic metabolic processes continue at a low level. The wasp then lays her eggs on the tarantula, seals the burrow, and departs. The living spider is her solution to having fresh, juicy baby food for her larvae once the eggs hatch. The larvae feed on non-life-sustaining portions of the spider's body until they are near maturation, at which time they consume the remainder, killing the tarantula.

Trap Door Spiders, Ticks, and Scorpions (Class Arachnida)

Three types of arachnids—spiders, ticks, and scorpions—are often found in the chaparral. Arachnids are most easily distinguished from insects by counting their legs. Members of this class, including the tarantula previously described, have eight legs, while adult insects have six legs. The bodies of insects are divided into three parts: the head, the thorax from which the legs emerge, and the abdomen. A spider's body has two parts: the front section includes the head and legs, with the abdomen behind. The ecology of chaparral arachnids is poorly studied overall, but a few are well known. Trap door spiders are well adapted to life in the chaparral, including the inevitable fires. Ticks are also well adapted to chaparral, and to other plant communities in a wide variety of habitats across North America. They are among the likely invertebrates to be encountered by the chaparral adventurer, especially in spring, when a hike in the chaparral is most inviting. Scorpions are also surprisingly common but are seldom seen by people not looking for them because they are nocturnal.

Trap Door Spiders

Members of the order Araneae, trap door spiders (Aliatypus spp. and Bothriocyrtum californicum, family Ctenizidae) live in burrows in banks and hillsides in chaparral. They prefer sunny, south-facing slopes with grass or low herb cover, where they receive the sun's warmth early in the day. They are called trap door spiders because the door to their burrow is hinged on the uphill side and has beveled edges to fit the sides of the burrow opening tightly, much like a ship's hatch.

Hunting by trap door spiders is a sit and wait process, like that used by the Coast Horned Lizard. This is an energy saving process for the spiders, and one that keeps them from becoming food for someone else. Trap door spiders wait for the unwary beetle or cricket to wander past the burrow, pouncing on it and sinking in their fangs with a quick movement. They quickly drag the prey inside their burrow, where they suck the juices from its body. They usually keep one of their eight legs in the door of their burrow so they can disappear quickly if a spider-eating predator should come by looking for a quick meal. When they are not hunting, the spiders hold their well-camouflaged door shut with their fangs, because they too are a nice juicy package for a larger predator. This precaution is often insufficient protection, however. Skunks (Mephitis mephitis and Spilogale putoris), in particular, are fond of trap door spiders, and they can quickly dig into the burrow to extract their prey.

Trap door spiders constantly remove dry soil from the burrow so that they can maintain high humidity and keep their body in contact with damp ground. The damp earth keeps temperatures down in warm weather and allows these rather large spiders to breathe without drying out. They can lose water rapidly if forced to be active when it is too hot and dry.

Trap door spiders are adapted to the periodic fires of the chaparral. During a fire their carefully constructed door burns off, exposing the opening to the burrow. However, the spiders survive because the vertically dug burrows are six to 11 inches deep, providing an environment that may remain cool enough for them to survive. Another advantage of the burrow is that smoke from the fire does not tend to be pulled down into the narrow, vertical shaft. A new door is fashioned by the spider within 24 hours of a fire. On the other hand trap door spiders may move to other locations after a fire. It is common to see the exposed upper portions of trap door spider burrows, without doors, sticking up like little chimneys on slopes during the months following fire. The upper layer of soil often erodes from these bare slopes, leaving the exposed necks of empty, silk-lined spider burrows standing well above the surface of the ground.

Ticks (Order Acari)

A person hiking through the dense vegetation of chaparral often picks up an unwanted companion, a tick. This is particularly true in winter and spring. These little arachnids sit on the edges and tips of vegetation, from which they drop onto passing animals when the plant is disturbed. Ticks are external parasites that extract blood by temporarily but firmly attaching themselves to the skin of the host animal, where they extract a blood meal. Fortunately, ticks usually take several hours to firmly attach, so you have time to discover and remove them before any harm is done. They are known to transmit a number of serious diseases such as tularemia (hunter's disease) and Lyme disease. An unfed tick is less than one-tenth inch in diameter, with eight grasping legs and often a surprisingly hard body surface (exoskeleton), but it can quadruple in size after a good meal, coming to resemble a small blimp with legs. Four species of ticks will bite humans and are commonly found in chaparral. Experienced hikers know that it is wise to inspect the entire surface of the body at the end of a day spent in dense vegetation in order to find and remove ticks. These little parasites prefer parts of the body that are snugly protected from exposure, such as the hairline at the nape of the neck, and places where clothing is in close contact with the skin—socks, underwear, and the like.

Scorpions (Order Scorpionida)

Chaparral scorpions vary in size from less than an inch to 2.5 inches from head to extended tail. They emerge from their shelters only at night. They live under rocks, in rotting wood, and in burrows they excavate. None of the species found in chaparral areas are life threatening, but they can deliver a bee-sting level of pain. The large and common Burrowing Scorpion (Anuroctonus phaiodactylus, family Vejovidae) is found throughout chaparral, and its burrows often line the sides of trails cut into slopes. It can be recognized by its stout body up to 2.5 inches long, and bulky, reddish brown claws. Unlike the burrows of spiders and insects, which usually have round openings, scorpion burrows are almond shaped, reflecting the flattened body shape of their owners. Because scorpions keep their burrows cleared of soil, they can easily be discovered from the small pile of fine sand grains below the lip of the opening. At night scorpions lie in wait at the burrow entrance, where they use their powerful claws to grasp and hold insects and other small invertebrates. One of the peculiarities of scorpions is that their bodies fluoresce when exposed to ultraviolet light. Scorpion collectors often search for them at night with portable black lights, under which they glow various shades of blue, purple, or green.

Other Chaparral Insects

Of course, many other insects occur in chaparral. One group that attracts some negative attention is the canyon flies (Fannia spp., family Muscidae, order Diptera). These small, gray flies are only about an eighth of an inch long but have the aggravating habit of landing on exposed skin and crawling into the eyes, nose, ears, or mouth in search of moisture. Although they do not bite, their persistence and sheer numbers can make them distracting and annoying.

A number of moths also live in the chaparral. Although they are generally nocturnal they may occasionally be seen at dawn and dusk. One notable species, the Ceanothus Silk Moth (Hyalophora euryalus, family Saturniidae, order Lepidoptera) is a beautiful chestnut brown color with a wingspan up to five inches wide (pl. 73). The sausage-shaped green larvae can be up to four inches long, and the body is studded with yellow tubercules (bumps).

Plate 73. A Ceanothus Silk Moth.

Along with moths, a number of butterflies, bees, and beetles are also found in chaparral, many of which are important for pollinating the flowers of the shrubs. Relatively little is known about these relationships, but it is likely that some are every bit as complex as that known for Yucca Moths. One group, that of solitary bees, is particularly numerous in chaparral, and as a rule each species feeds on only one plant. A survey of chaparral at Pinnacles National Monument in the Central Coast Ranges found 410 species of bees, a higher number than known from any other ecological community in North America, and one-tenth of all the bee species known in the United States.

It would be reasonable to suppose that when chaparral is swept clean by an intense wildfire, all insects would be temporarily exterminated. This is not the case. Many species of chaparral insects can survive fires by living underground, inside burls or trunks and stems of larger plants, or under rocks and other protective elements. These species may be stimulated to activity by the heat of the fire, flying to fire or freshly burned plants to reproduce, as is the case with the fire beetles (Melanophila spp.) described in chapter 3.A study of insects in the months following an intense wildfire in chamise-ceanothus chaparral in the San Gabriel Mountains showed a peak of insect species and abundance that declined over the following three years. These insects may have survived the November fire in recesses beneath the ground, or they may have quickly crossed the distance of a mile or so between the burned study area and the nearest unburned chaparral. The large number of plant species that quickly appeared and flourished after the fire may have contributed to the peak in insect diversity. In general, most species of insects are closely tied to the plants upon which they live. The flush of insects after fire may explain the abundance of insect-eating animals in chaparral at this time. For example, the total number of bird species observed in recently burned chaparral is about the same as in mature chaparral, even though the particular species composition is somewhat different before and after a fire.