It’s the last week of September, and here in northern California’s Bay Area, the fall raptor migration is peaking, as far as sheer numbers go. We still have a lot of variety to go (we’re waiting for some of the more northern birds to make their way down from Alaska and Canada), but the daily totals we have in our sky right now are hard to beat. The Rough-legged hawks haven’t showed yet, and the Ferruginous Hawks have just started to pass through.
Many people around San Francisco don’t realize it, but just on the other side of the Golden Gate Bridge is one of the only spots on the West Coast where you can see a noticeable hawk migration. An abundant food supply (small birds, rodents, snakes, etc.), and inviting updrafts created by coastal hills bring hawks, falcons, kites and eagles into the area on their southern journey. They are stopped by the Pacific Ocean (they don’t like to fly over water- no updrafts, so it is too much work and too little food), and are turned south. They are spread out, but begin to be funneled together by San Francisco Bay (if you look on a map, Marin County is almost becomes funnel shaped as it approaches the Golden Gate, with the Pacific on one side and the Bay on the other). And so you get numbers. Sometimes more than a thousand a day.
It makes it an ideal place for the Golden Gate Raptor Observatory, a largely volunteer raptor studying group that is led by a small group of dedicated raptor biologists. They spend the season counting the different raptors that migrate through (here are their daily hawk watch totals). Throughout the migration season they stand atop Hawk Hill in a loose circle, with a different team monitoring each of the cardinal points. They stand there in the elements gathering data to further our understanding of raptors. A very brief article I wrote for a travel website on how to find your way to Hawk Hill has been syndicated in Salon’s recent article on fall migrations.
While the migration will continue strongly for a few more weeks, its peak will conclude around the end of September. During the average migration we see 19 different species of raptor. I hope you can make it out there to enjoy some of the activity.In the meantime, enjoy the slideshow of raptor photographs at the top of this post. I can let all of you guess each of the species, or I can caption each image with what each bird is. Let me know what people prefer.