Birds Flocking to the Presidio

Presidio of San Francisco (March 15, 2010) — For Chicago-area transplant Stephen Phillips, the Presidio bird count was “something amazing to be a part of.”

“The number of different species just blew me away,” says Phillips, a biological science technician with the Presidio Trust. “In the Midwest, we’d see between 70 and 80… and that was in a record year!”

Phillips recently joined other birdwatchers as they fanned out across the Presidio for the annual census of the park’s bird population. Trekking through most neighborhoods in the park, they spotted everything from modest songbirds to the park’s impressive Great Horned Owls. All told, birders counted 4,141 birds representing 109 different species. It is believed that about 200 bird species use the Presidio, ranging from year-round residents like Anna’s Hummingbirds, Red-shouldered Hawks, and Great Egrets to migratory species like Red-throated Loons.

Among the highlights of this year’s count were six Red Crossbills. “My personal favorite,” says Phillips. The Red Crossbill is an especially mobile species that migrates in response to food availability. “It’s always a surprise when you see them because they’re known to be so transient and hard to track down.” The Wrentit, which almost became extinct in San Francisco in the last several years, was spotted near Lobos Creek, further raising hopes that the species is finding refuge and surviving in the natural areas of the Presidio.

The numbers from the Presidio’s bird count were added to the totals for the broader San Francisco bird count, which encompasses an area of 177 square miles, from San Bruno to the Golden Gate Bridge, and from Yerba Buena Island to Fort Funston. Scientists use the data to study how bird populations are changing, usually in response to man-made alterations in land use and habitat. The goal is not to get an exact number of individual birds, like a rancher would count how many head of cattle in his herd, for instance. Rather, the purpose is to get an overall sense of how abundant birds are in an area.

“The focus is really on the diversity of species, not on the number of individuals,” says Phillips. “The count reflects the wide range of habitats in the Presidio. One of our main goals when it comes to habitat management is maintaining that diversity. The broad array of species using the Presidio on a consistent, year-to-year basis provides evidence of a healthy bird population, and implies that we’ve been successful in preserving habitat.”

While the number of species remained virtually unchanged from last year, fewer birds were counted this year than last, a development Phillips attributes to El Niño.

“The Presidio is a popular stopover for migrating birds. The warmer, wetter weather can throw them off their normal route and instead they migrate to cooler, drier areas.”

The Audubon Society has been conducting bird counts since 1900. The first one in San Francisco was conducted in 1915. For a complete count, visit: http://birds.audubon.org/christmas-bird-count.

The Presidio Trust was established by the United States Congress in 1996 to administer the Presidio of San Francisco, an urban national park that is part of the Golden Gate National Recreation Area and is located at the base of the Golden Gate Bridge. The areas overseen by the Trust include expansive open space and spectacular views, a 300-acre historic forest, and rare and endangered plants and wildlife. The National Park Service oversees the coastal areas of the Presidio. The park comprises nearly 6 million square feet of buildings, including 469 historic structures that contribute to the Presidio’s status as a National Historic Landmark District.