The definition of a predator is quite simple: an animal that eats prey. All predators actively kill or scavenge another animal for food. Types of predators are classified as follows.
Hypercarnivores, such as members of the cat family, eagles, and snakes, must eat meat because of their digestive-system needs. Also referred to as obligatory carnivores, they must have some meat in their diet. These species engage in active pursuit or ambush behaviors.
We describe other animals as omnivores, which means they are able to fulfill their dietary needs from a variety of plant and animal sources. Many omnivores are opportunistic predators, which don’t always actively hunt but do take advantage of prey or carcasses they encounter as they forage. Opportunistic predators will kill and eat a wide variety of prey, unlike other predators, which specialize on a narrow range of prey.
Some predators, such as wolves, use social cooperation to kill animals much larger than themselves. Other predators are solitary in their hunting behaviors.
An apex predator resides at the top of the food chain, meaning that as adults, members of that species are not preyed upon by any other predator.
Predators are often described as keystone species for their essential role in ecology. Predation is a key element of ecosystems, preventing overpopulation of prey species that can be extremely destructive to the land. These wild hunters increase biodiversity by not allowing one species to dominate all others. Predators also maintain the health of a prey species by eliminating ill or weak members of the group.
When predators are eliminated or severely reduced through habitat loss, the entire ecosystem suffers. For example, when wolves were eliminated and landscapes changed, coyotes and other smaller predators were able to increase their populations and ranges. As an unintended consequence, the coyote is now the primary killer of domestic livestock in the United States.
When apex predators are restored, some biologists posit that a trophic cascade occurs from the top of the food pyramid. The herbivores that overgraze are reduced, plant ecosystems are restored, and other species flourish again.
Predators live in all ecosystems. They inhabit woods, mountains, deserts, suburbia, cities, the sky, the water, and, in the case of domestic cats and dogs, even our own living rooms. Most animal predators are mammals, but birds and reptiles are significant hunters of prey as well.
The word mammal was first used by Linnaeus in 1758, derived from the Latin word mamma, for “breast” or “teat.” Besides the ability to nurse their young, this class of animals also possesses hair, three bones in the middle ear, and a neocortex — the part of the brain involved in higher functions. Most mammals are also placentals, which feed their offspring during gestation through a placenta and give birth to live young. Just five mammal species are monotremes, or egg layers. Like birds, mammals are also warm-blooded or able to maintain a stable body temperature.
Mammals are highly diverse and adaptable, living in habitats from land to sea to air. They vary in size from the largest sea and land mammals — elephants and whales — to the tiniest bats less than 2 inches long. Rodents, shrews, bats, whales, dolphins, hoofed ungulates, and primates, including humans, are all mammals.
With some 10,000 species worldwide, birds are both friend and foe to farmers. They are an essential source of meat and eggs, and they can be pests to both fruit and grain crops. While many birds are predators, only a few species are a threat to livestock, poultry, or pets. In addition to the well-known birds of prey — eagles and hawks — owls, black vultures, crows, ravens, jays, and magpies can also prey on farm animals and pets. More rarely, seagulls will attack and kill livestock.
More closely related to birds than to mammals, reptiles truly represent an ancient group of animals. Reptiles are often described as ectothermic, or cold-blooded, which is not quite accurate, as their blood temperature does vary, but they are generally unable to generate sufficient body heat on their own. This low metabolism conserves energy and therefore requires less food or fuel. Reptiles exist on far less food than equivalently sized mammals do. Reptiles also have eyes adapted specifically to daylight, although some snakes have heat-sensing organs as well.
Most reptiles are carnivores. While crocodilians, snakes, and turtles are not major predators in an agricultural setting, in specific situations they are a threat to domestic livestock, poultry, and pets.
We are continually learning more about animal evolution and the relationships among species and subspecies. Genetic research can be especially revealing, but it will be tested and refined as the dynamic process of science continues.
Vulpes vulpes, the red fox
Taxonomics is a biological method of naming, classifying, and organizing groups of organisms by shared characteristics and evolutionary relationships. At first, physical scientists identified members of a species by describing attributes and behaviors. Appearances can certainly deceive, however, and more recently DNA sequencing is revolutionizing the determination and classification of species. It is also important to note that common names like lion or hawk may or may not correspond to the actual species.
Family. A group of related genera with the same ancestors
Genus. A group of species with the same ancestors
Species. A group of animals that are capable of producing fertile offspring
Subspecies. A group within a species that shares a unique geographic area, physical characteristics, or natural history
Clade. A group of organisms that are closely related and share a common ancestor
By observing the “signs” of visiting animals, you can learn a great deal about what lives in your area, even before you acquire livestock. Record notes and take photographs for future reference and comparison.
Scat can vary in size and content for every individual, but it can reveal clues about the type of animal and its diet. It can be especially useful when combined with other signs. Both fresh scat and dry scat are potentially dangerous to humans. Handle either with great care, and do not inhale dry particles.
Track size varies with age and gender of the animal, regional or subspecies variations in size, the surface of the track impression, and the weather. In this book, track sizes measure the deeper minimum impression, not the more variable, broader surface outline. Tracks may also reveal tail drags.
Bounding: Weasel
Waddling: Raccoon
Walking Bobcat
Trotting: Red Fox
Gait, or the way an animal moves, leaves a typical pattern of prints and can be classified into broad predator types of walking, trotting, waddling, and bounding. Stride impressions also vary individually and with terrain. Animals may walk or trot with a direct-register (rear foot lands in front print), overstep (rear foot lands beyond the front print), or understep (rear prints behind front prints). Canines often side-trot with an angled body, their hind prints to one side of their front prints. In a straddle trot, the hind tracks go to both sides of the front tracks. Strides are measured from the point one foot touches the ground to the next point of that same foot.