|White-crowned sparrows are among the species that spend the winter in Southern California. Photo by J.J. Meyer|
September can be bittersweet, as we say goodbye to the migratory birds that spent the summer nesting and raising their young in Southern California backyards. Many species, including hooded and Bullock’s orioles, black-chinned and Costa’s hummingbirds, black-headed grosbeaks and cliff swallows, have already begun their journey to their winter grounds in Mexico and Central America. But soon our winter residents such as yellow-rumped warblers, dark-eyed juncos and flocks of white-crowned sparrows will be arriving.
For migrant songbirds, fall is all about moving on from their nesting grounds to their fall and winter feeding territories. Many birds are long-distance travelers, including several species of hummingbirds that travel thousands of miles from the Pacific Northwest and Canada to the southern region of Mexico.
September and October are the key months for songbird migration, said Trude Hurd, Project Director of Education for Sea and Sage Audubon.
“The decrease in daylight is the primary environmental cue that signals it’s time to migrate,” Hurd said.
Shorter days indicate that fall is on the way. “Birds are sensing the change,” she said.
“Decreasing daylight can trigger what’s called a ‘false spring. The birds confuse the change in daylight with spring and begin to sing to defend their territory, but it doesn’t last long. We get calls at the Audubon House this time of year from people asking why the mockingbirds are singing.
“The breeding season is over, but you may still see young birds learning to fend for themselves,” Hurd said. The presence of juveniles can also make bird identification tricky this time of year. Many species will not display their adult plumage until after their first year.
By the beginning of September, many songbirds have started to molt, a systematic process of replacing feathers. “Molting usually kicks in after breeding because it’s very calorie-intensive activity,” she said. Many species undergo a complete molt on or near their breeding grounds, which allows them to migrate south with a new set of feathers.
This time of year, giant flocks of crows form at dusk as they head to their roosting areas for the night. At daybreak the noisy corvids return to their respective territories to feed.
The fall arrival of sharp-shinned hawks presents an additional challenge for songbirds that already cope with Cooper’s hawks as year-round residents. According to the Cornell Lab of Ornithology, studies indicate the presence of birdfeeders won’t greatly increase a bird’s chances of being taken by a sharp-shinned hawk — the hawks get the majority of their diet elsewhere. However, the Lab suggests taking feeders down for a couple of weeks if a hawk has been a regular visitor. The hawk will move on and the songbirds will return when the feeders are replaced.
In late fall, watch for cedar waxwings and American robins that often flock together in search of food. These nomads typically arrive when native berries are ripe.
Homeowners can help migrating birds in a number of ways. “First, provide fresh water,” Hurd said. “The weather will still be hot for the next month and the Santa Ana winds kick up this time of year, which dries out the vegetation.”
Other tips include turning off outdoor lights or directing them downward. The majority of birds migrate at night, navigating with the sky. They can become disoriented when flying over cities, where they crash into buildings.
Keep cats indoors. Roaming cats kill billions of birds every year.
Break up the reflecting surface of windows by applying decals, bird tape or other window coverings.
Fall is the best time to plant native trees and plants. Birds rely on native plants for food along their migration route. It’s also the best time to trim trees.
For a plant list and information on how to create a bird-friendly garden, go to seaandsageaudubon.org.