WILD NEIGHBORS: Alameda’s Turn (and Terns)

By Joe Eaton
Thursday December 15, 2011 - 10:49:00 AM

It’s been a long time coming, but the Alameda County Breeding Bird Atlas is finally available from Golden Gate Audubon. Based on intensive fieldwork in the 1990s, this book is a splendid addition to the shelf of Bay Area atlases. So far we have Marin, Sonoma, Napa, Contra Costa, Santa Clara, and now Alameda. I believe a Solano project is in the works. A San Francisco atlas would be slender, but perhaps surprising. How about it, Audubon? 

The Alameda atlas has text by Bob Richmond, Helen Green, and David Rice; occurrence maps by Rusty Scalf, who has been documenting the spread of western bluebirds in Berkeley; and handsome paintings by Hans Peeters, a local artist who also illustrated the mammal, raptor, and owl guides in the UC Press California Natural History Guide series. 

The compilers used standard survey protocols to categorize the likelihood that birds are nesting, not just passing through. A singing male in suitable habitat during breeding season rates a “possible.” For “probable,” you would need observations of territorial defense, courtship, mating, or agitated behavior by presumed parent birds. “Confirmed” requires nest building, eggs or young in a nest, eggshells, adults carrying food, or, in the hand, physiological evidence of breeding like an enlarged brood patch. 

Surveys produced evidence of breeding for 175 bird species; four more were added after the atlas period. As always with these projects, there were a few surprises. Isolated breeding records for lesser scaup, redhead, pelagic cormorant, black-chinned hummingbird, purple martin, hermit thrush, cedar waxwing, yellow-breasted chat, yellow-headed blackbird, and pine siskin may have been one-off events. Alternatively, the chat record may represent the last stand of an almost-extirpated population that depended on dwindling riparian habitat. Some birds, like the reclusive sharp-shinned hawk, were found to be more abundant as breeders than expected. 

The atlas is not just a collection of maps: it’s a compendium of stories. Having birded the county for some years, I see it as a kind of family album. Here’s the Arctic tern that paired with a local Forster’s tern at the Hayward Regional Shoreline and produced several broods of confusing hybrid offspring. Here’s the triumphant return of the bald eagle as a breeding species, when a female hatched in Alaska and a male of unknown provenance set up housekeeping at Del Valle Reservoir. Here’s the whole saga of the California least terns at the former Alameda Naval Air Station.  

Here’s the lowdown on the ubiquitous Canada geese, all apparently descendants of hunting casualties introduced to Lake Merritt by naturalist Paul Covel in 1956. 

One of several appendices lists birds whose county ranges and populations have increased. It’s an impressive roster, including grebes, egrets, gulls, stilts, avocets, corvids, and nuthatches. Cooper’s and red-shouldered hawks have prospered in urban areas. Some songbirds have followed plantings of conifers (red-breasted and pygmy nuthatches, dark-eyed juncos) or palms (hooded oriole.) The recent crow boom is acknowledged, although not explained (“It is unknown why American Crow has increased noticeably in urban areas in recent years, because food sources have always been readily available there.”) 

Another appendix notes species of special concern whose breeding populations have been declining: some raptors, the clapper rail, and a number of songbirds with special habitat requirements. The loss of coastal wetlands and riparian zones is a recurring factor. 

Anyone with even a half-serious interest in local bird populations should have this book. It’s available at the Golden Gate Audubon office at 2530 San Pablo Avenue for $22 ($20 for Audubon members) and would make a fine holiday gift for the birders on your list.