Spring migration is upon us!
By Conservancy Science Director Mike White
Photo by Conservancy Volunteer Chuck Noble
Spring is here—the wildflowers are in bloom, deciduous oaks are leafing out, and the migrants are arriving! The migrants I am referring to are birds. Keep your eyes peeled because it is not out of the question to see flocks of white pelicans, turkey vultures, California gulls, or long-billed curlews passing over our office in the Grapevine Canyon Pass.
Many different animal species migrate, and migrations can be some of wildlife’s most spectacular shows. Ecologically, animals migrate in response to changes in their environment, such as migrating away from an area with a reduced amount of food or habitat quality during severe winters, or migrating to a very food-rich area during the breeding season.
Species migrate across vastly different distances, and the distances that some species migrate are hard to fathom (the Arctic tern migrates over 50,000 miles each year!). Species that don’t migrate deal with weather and food availability in different ways, and migration is just one strategy that animals use to deal with changes and uncertainties in their environment. But it must be a successful strategy!
Wintering Bald Eagle in the San Joaquin Valley. Photo by Chris Gardner.
Butterflies migrate, fish migrate, birds migrate, bats migrate, pronghorn migrate, whales migrate—migration is a strategy that has developed across a diverse array of species. At Tejon however, we really experience the migration phenomenon through birds.
In fact, while many species at Tejon are year-round residents, many of the common birds that we see on the Ranch at different times of year, don’t actually live here year-round. Some migrate here in the winter from breeding grounds farther north with more severe winters than ours. For example, we usually have two or three bald eagles hanging around the San Joaquin Valley, Lewis’s woodpeckers and yellow-rumped warblers in valley oaks, a number of wintering raptors like ferruginous hawks, and flocks of glorious mountain bluebirds showing off in our grasslands.
A mountain bluebird shows off his colors in the Antelope Valley. Photo by Chris Gardner.
A Lewis’s woodpecker in the winter sunlight. Photo by Chris Gardner.
A ferruginous hawk strikes a regal pose. Photo by Chris Gardner
During the spring and summer, these winter visitors are replaced by many species that wintered down in the southern hemisphere, and are either coming here to breed or passing through on their way to breeding grounds farther north. These include species like swallows (including the Purple Martin featured later in this newsletter) and swifts, orioles, tanagers, hummingbirds, and many other songbirds.
Vermillion flycatchers migrate through Tejon but are not known to breed here (yet!). Photo by Chris Gardner.
While we can see flocks of some species migrating during the day (think pelicans), many smaller bird species actually do most of their migrating at night when there are few predators and smoother flying conditions. When the sun comes up, these nocturnal migrants need to find a place to land and fuel up. Sometimes factors combine and lots of individuals of lots of different species of nocturnal migrants will all drop down at first light to look for a place to spend a day or two, producing a phenomenon birders call “fall out.”
A Bullock’s oriole in a Valley oak. Photo by Chris Gardner.
Scott’s orioles nest in Joshua tree woodlands in the Antelope Valley. Here with an insect larva in his bill. Photo by Chris Gardner.
Western tanagers are colorful breeders on the Ranch. Photo by Chris Gardner.
Natural areas such as Tejon are very important for our resident wildlife, but are also very important for our migratory visitors. The Conservancy is working hard to keep the Ranch a sanctuary for our migrant friends through our stewardship activities. We hope that you will join us in helping them!
Western kingbirds are often one of the first migrants to arrive in the spring. Photo by Chris Gardner.
By Conservancy Volunteer and California Naturalist Chris Gardner
The Purple Martin (Progne subis) is the largest North American swallow. Its flight is strong and graceful, with alternating rapid wing beats and long glides. The wings are pointed; the tail notched. Males are dark, glossy purple-blue. Females have duller upperparts and mostly gray underparts. They feed on flying insects, catching prey in mid-air, flying up to 45 mph when foraging.
Purple Martins winter in South America and return to North America as a summer resident from mid-March to late September, breeding between May and August. They are broadly distributed throughout most of eastern North America. In western North America, Purple Martins occur locally in the Rocky Mountains, the Sonoran Desert and Pacific Coast states.
Purple Martins evolved as a secondary-cavity nester, relying on cavities already created by woodpeckers. In the eastern United States, the species has switched to human constructed martin houses due to the competition of natural tree cavities from European starlings and house sparrows. In the western United States, it still nests almost exclusively in woodpecker holes.