Get to know the Bay Area birds of autumn
By late September, our summer birds have almost entirely left and our winter birds have begun to arrive: Fall migration is in progress. This process has many aspects, many exciting new arrivals to welcome as the Earth makes its progress around the sun and daylight diminishes in the north, sweeping birds southward and westward to the tranquil coasts of California. What changes do we see in the autumn world of birds, and where do we see them?
First, the departures. In backyards, orioles were the most striking of our summer birds, golden wonders that visited hummingbird feeders. Grosbeaks may have passed by your seed feeders or western tanagers may have sought berries in your yard. Western flycatchers and their cousins joined the Wilson’s and orange-crowned warblers in the woods, while swallows circled overhead. Now all of these have journeyed south, mostly to Mexico and Central America, with some swallows traveling farther.
But, in turn, we welcome new birds to our neighborhoods, most of whom are just beginning to appear. Most familiar — or soon to be so — are two sparrows, the white-crowned and the golden-crowned sparrow. Common visitors to feeders for both seed and suet, these birds gather in flocks in weedy fields, roadsides, brushy patches and backyards. And when they make their first arrival, fresh from their northern breeding grounds, they often sing, issuing standout melodies in the more quiet autumn soundscape. Listen for the melancholy “I’m so tired” of the golden-crowned sparrow or the related song of the related white-crown: a similar clear, high-whistled note commences the performances, but followed in this case by a variable jumble of descending notes.
There are many more songbirds on the move as well. Less-common sparrows like white-throated, fox and Lincoln’s sparrows arrive in conjunction with the abundant crowned sparrows. Ruby-crowned kinglets will soon become inconspicuously ever-present, tiny and uncolorful birds that nonetheless move with a belligerent hyperactivity through the foliage of both neighborhood and woodland trees in search of tiny insect prey. Our two winter warblers, the yellow-rumped and the beautiful Townsend’s warbler, join the kinglets in the canopy and occasionally visit feeders when the weather turns cold.
You can see the changes of autumn even among birds that are not entirely new. Finches are a good example of the instinct toward seasonal flocking, with both the red house finches and the yellow goldfinches gathering in large flocks of dozens to hundreds. Dark-eyed juncos and pine siskins, while present year-round in the Bay Area, likewise appear more numerous, with their populations also swollen by additional arrivals from the north. And even nonmigratory birds like chickadees, creepers and vireos join arriving kinglets and warblers to form mixed-species flocks that roam together through the woods, sharing their awareness for greater safety from predators.
Beyond the neighborhood and woods, birds are likewise on the move. Shorebirds began their journeys early and travel fast, many of them after a short breeding season in the far, far north, so birds like sandpipers, yellowlegs, willets, godwits and curlews are already present in abundant numbers. They will continue passing through the many wetlands around the Bay for months, with different species peaking at different points in fall in a constantly changing kaleidoscope of birds. While many shorebirds will continue southward, most species will be locally represented throughout the winter, allowing us to enjoy their presence well into spring.
Other groups are at an earlier stage in their southward journeys. Hawks, eagles and other raptors are on the move — now’s the time to witness migration over Hawk Hill in the Marin Headlands, while the later months of fall and winter give us a chance to enjoy greater numbers of sharp-shinned hawks and eagles, along with the new presence of the tempestuous merlins and mighty ferruginous hawks. Most waterfowl are likewise still to arrive: While a few species — mallards, Canada geese and mute swans — do breed locally, the vast majority of our ducks are winter birds. Shovelers and pintails, teals and ruddy ducks, buffleheads and goldeneyes, scaups and canvasbacks — soon you will get to practice this vocabulary of the wide-billed and web-footed on which we feast our autumn eyes.
Jack Gedney’s On the Wing runs every other Monday. He is a co-owner of Wild Birds Unlimited in Novato and author of “The Private Lives of Public Birds.” You can reach him at jack@natureinnovato.com.