Double-crested cormorants fly over downtown in V formation. Like bicycle racers, each one drafts off the one before.
Birdwatchers can look a bit odd, with their floppy hats and dangling binoculars, but on certain nights in spring and fall, Los Angeles’s birding tribe looks stranger than usual. Donning dark glasses and aiming their telescopes at the full moon, they watch a migration in progress.
Migrating birds like thrushes, warblers, and sandpipers fly all night, landing to feed and rest once the sun rises. By watching carefully, you can see them pass overhead, backlit by the moon. On a clear night, when the moon is too bright, sunglasses cut down the glare.
Sometimes you can tell which species is passing overhead by their call; other times, by shape and flight style. Moon-watching may seem odd, but according to bird expert Kimball Garrett, it’s a great chance to compare the patterns of nocturnal migration across the city. Do more migrant birds pass along the foothills than over the flat LA Basin? Are many birds moving right along the coast? Scattering observers over the region allows us to answer these questions.
Double-crested cormorants fly over downtown in V formation. Like bicycle racers, each one drafts off the one before.
All animals travel during their lifetimes, but some animals take truly magnificent journeys of dozens, hundreds, or even thousands of miles. Southern California in general—and the Greater LA area in particular—holds vital resources for these long-distance migrants, who take advantage of our cities and suburbs to rest and refuel before continuing their long treks or flights.
Each year, in every habitat and ecosystem across the globe, some tiny voice inside various animals big and small compels them to leave everything behind and walk, fly, or swim to a distant land. Migrating animals have long puzzled humans. Before we had technology to track them, they seemed to appear without warning and disappear just as fast. Nobody knew where they came from or where they were going.
Many migrants aren’t consciously aware of the cues telling them it’s time to move. Even the simplest of creatures with barely a brain to speak of—like microscopic plankton in the ocean—use environmental triggers to precisely time their travel. Those triggers might include temperature, day length, the availability of food, the drive to mate, or dozens of other cues. To be considered a true migration, an animal’s movements should be part of an annual or seasonal cycle: birds in the Northern Hemisphere that migrate south for winter and north for summer, for example.
Some of the world’s most impressive migrators are the great whales—like the gray whale, the humpback, and the fin whale—some of which travel from the warm tropics to the icy poles and all of which can be seen off our coast (see Trip 25). The most massive of these ocean giants is the hundred-foot blue whale, as long as a jumbo jet, with a heart the size of your car. The California population of this mega marine mammal spends its winters breeding near Costa Rica and its summers gorging on food off the California coast.
One of the largest dragonflies in the LA area is the common green darner. It’s also one of the best-known migrating dragonflies, but the migration itself is shrouded in scientific mystery—no one knows exactly where they come from, or where they’re going.
We do know they appear in early spring before other, non-migrating dragonflies begin to take flight. Some green darners stop here in Los Angeles for a quick break on their journey north, others stay and set up shop.
Because their young develop in wetlands, they find a nice spot to hang out near water then set about finding a mate and laying eggs in streams and ponds. By the end of the summer, their nymphs have morphed into adults who begin their own migration south. Some scientists think they spend their winters in Mexico or the Caribbean. Though nobody knows their destination for sure, many entomologists think they aim for areas their parents came from.
Green darners aren’t the only dragonflies that migrate through Los Angeles. Others making epic flights include black saddlebags, wandering gliders, and variegated meadowhawks. In late summer you can sometimes see large groups of dragonflies congregating on hilltops as they journey south. In some cases, hundreds of thousands of dragonflies have been seen flying, as if carried by a river of air, along our coasts, mountain ridges, and waterways.
Millions of green darner dragonflies migrate north in the spring and south in the fall. They can fly up to thirty miles per hour!
Though they weigh only as much as six sheets of printer paper, monarch butterflies make a mighty migration. Populations in the eastern United States famously fly an epic two thousand-plus miles from summer feeding grounds in Canada to overwintering spots in Mexico.
Monarchs in California are a separate population from those east of the Rockies and migrate along a different path. Like their eastern cousins, they may fly as far north as Canada in summer, but during winter they settle along California’s coastline. The Golden State’s wintering population, seen from Ensenada, Mexico, all the way to Sonoma County, numbers in the hundreds of thousands.
On cool days, wintering monarchs stick to their roosting trees, sitting motionless, with their wings closed as if pretending to be leaves. But on sunnier days, you can see them flying about until late afternoon, when they return to their roosts for the night.
Many monarch roosts in Los Angeles are located on private property and can be tough to see, but some are publicly accessible. In October and November, visit Leo Carrillo State Beach for a look at these gold and black stunners (watch the eucalyptus trees along the creek, near the campground), or head even further north to the Monarch Butterfly Grove in Pismo Beach. An hour beyond Pismo Beach, you can see more amazing migrators: northern elephant seals at the Piedras Blancas rookery. They migrate as much as 13,000 miles in a year.
Some impressive migrations span thousands of miles, but other, smaller migrations occur entirely within Los Angeles. Meet the convergent ladybug and its altitudinal migration. This species of everybody’s favorite beetle looks familiar—its elytra (the hard front wings that protect their more delicate flying wings underneath) are the classic reddish orange with black spots—and you can find them in just about any garden or backyard from late spring through early fall. But once the weather starts to cool, these ladybugs head for the hills—literally.
Groups of several hundreds or thousands congregate in mountain canyons, where they bulk up by eating pollens and nectar, just like bears preparing to hibernate. The fat they pack on helps them survive winter. They’ll spend up to nine months hibernating, often buried beneath the snow where the earth keeps them just warm enough. Once the snow melts, the ladybugs emerge and fly back to lowland valleys and coastal areas to begin feasting on aphids again.
Some ladybugs have been seen migrating too far, though. The Santa Ana winds, which tend to blow through early spring when ladybugs are emerging from hibernation, can blow them well past the coast and out to sea—a hazard of their migration style.
Ladybug migration isn’t sophisticated. It’s governed by fairly simple—and rigid—rules. Once they’ve eaten up all the aphids, exhausting their food supply, the ladybugs pack up and fly toward the mountains. If lots of aphids are around, the ladybugs have no reason to go anywhere.
Convergent ladybug migration is also directed by the amount of daylight. When days become shorter at the end of the summer, it’s time to begin the winter migration towards the highlands. When days become longer in the spring, it’s time to begin the spring migration towards the lowlands.
If the Santa Anas threaten to push the ladybugs out to sea, they can’t wait it out or alter course and head back toward the mountains. The rules that dictate their migration are too inflexible. The lost ladybugs might find a piece of driftwood or boat to cling to, but it’s usually too late. Before long, they’ll either starve or drown.
The dead and dying ladybugs often get washed up on the beach. Life is tough for a wayward beetle.
Los Angeles sits right in the middle of a four thousand-mile bird highway, a sort of endless conveyor belt of feathered critters coming and going throughout the year. Every year, at least a billion birds use this migration highway. Some travel the whole length, others just dip in and out along small sections.
There are four bird highways crossing North America from south to north: the Atlantic Flyway, which connects the Caribbean with Greenland; the Mississippi Flyway, which connects the Gulf Coast with Central Canada along the river for which it’s named; the Central Flyway, which connects South and Central America with central Canada through the Great Plains; and our very own Pacific Flyway, which connects Patagonia with Alaska along the Pacific coastline.
In some places, the Pacific Flyway is one thousand miles wide. The animals that use it need quality habitat to rest in along their journey. If too much of that habitat gets paved over, converted into farmland, or degraded, the long-term survival for these species starts to look bleak. Some more adaptable birds, like the Vaux’s Swift, might be able to substitute an urban chimney for a hollowed-out tree trunk, in which to roost, but others are more picky, or less lucky.
This is why many biologists have started to think about conservation not just in terms of preserving quality habitat, but in terms of preserving the links—or connections—between those habitats.
It’s useful to think of nature in a place like Los Angeles as an ever-changing mosaic rather than a simple collection of native and introduced species. Even though some animals only visit a few days or weeks, the habitat they find in Los Angeles is just as critical for their survival as the habitats at either end of their migration.
We’re lucky to have the opportunity to coexist with these visitors. They remind us that the environment is always changing, animals are resourceful, and nature can be found everywhere. Even within a Northridge backyard garden, or a chimneystack downtown.
In winter, mountain birds like this chickadee come down from higher elevations to investigate foothill yards and parks. This is called altitudinal migration.
