Let me be clear about something: I’ve been enjoying San Francisco’s Fleet week for decades, often anchoring my boat in Aquatic Park to partake of the spectacle.
For the past three years, however, I’ve participated in the Golden Gate Raptor Observatory’s Hawkwatch program, monitoring the autumn migration of 19 species of diurnal raptors from mid-August through early December. This is citizen science at its best; our teams have assembled a 30-year database of what comes down the Pacific flyway.
I’ve been spending my Saturdays on Hawk Hill in the Marin Headlands, just north of the Golden Gate. This is one of the best places on the planet to monitor migratory activity because it’s where raptors coming down the coast get squeezed by the ever-narrowing Marin peninsula. Southbound birds suddenly feel trapped—they’ve got the Pacific Ocean to their right, San Francisco Bay to the left, and the lesser expanse Golden Gate ahead. They realize they’ll have to make the jump across water, which is something a savvy hawk doesn’t want to do because it knows that there are no thermals out there where it’s wet. That means they’ll have to flap their wings rather than soar, which could lead to serious energy depletion.
They tend to circle once they get to hawk hill, building up both altitude and courage before making the jump.
The Saturday II team was out in force yesterday despite the morning fog. When it finally burned off we realized that it wasn’t going to be a peak day—we measure our success in terms of “Hawks Per Hour”—because there wasn’t any wind. The larger raptors, such as eagles, tend not to travel on windless days. They’ll wait for a brisk northwesterly to help them along.
It’s hard not to be distracted by the Navy’s airshow when nature’s airshow starts to fizzle. Fortunately, an ornithology class from UC Santa Cruz showed up, and Saturday II doubled down on its focus. We wanted those kids to see some good birds.
I couldn’t help glancing over in the general direction of the air show from now and then, and I couldn’t help but notice the haze it was producing on such a windless day. I found myself wondering whether anyone had ever calculated the carbon footprint of Fleet Week.
Hawkwatch lasts until 3:30, at which point most diurnal raptors are looking to roost. The Blue Angels took the stage at 3:00. They were hard to ignore.
One of the smallest raptors to grace Hawk Hill is the Sharp-Shinned Hawk. In Hawkwatch shorthand, we call these birds “Sharpies,” They’re accipiters, forest birds, with short wings and a long tail that help to navigate between trees. They’re so light, with the skinniest legs you’ve ever seen on a hawk, that one of the ways we can discern between Sharpies and their larger accipiter cousins, Cooper’s Hawks, is by watching whether they are being buffeted by the wind.
Yesterday we counted 56 Sharpies, far fewer than the 191 we’d counted on our previous outing. The ones we saw were working a lot harder than the ones we’d counted two weeks ago. Accipiters are characterized by a “flap, flap, glide” flight pattern where the glides last for at least ten seconds on a good day. Yesterday, the birds were lucky to glide for five seconds in between flaps.
Along with one of our interns, I’d rotated to the South quadrant at 2:30. It’s the slowest quadrant because by the time most birds show up there they’ve already been counted by team members in the other quadrants. There aren’t a lot of birds heading north in October.
At 3:05, right after the Blue Angels roared over the Golden Gate Bridge for the first time, climbing with their afterburners ablaze, I spotted two juvenile sharpies, a male and female, the female being significantly larger than the male. I focussed my binoculars on the female, who was coming directly at me.
I don’t often get a head-on view of a sharpie, at least not for long. The first thing I noticed was its eyes: sharp-shinned hawks have relatively large eyes given the size of their heads. Imagine what it would look like of you put a hawk’s eyes on a pigeon’s head, and that’s what a sharpie looks like head on. This juvenile seemed more bug-eyed than most. Then I noticed that the bird wasn’t gliding at all. She was flapping vigorously, constantly, as if the devil itself were in pursuit.
She wasn’t more than five feet over my head when she crested Hawk Hill. Unwilling to sacrifice altitude for speed, she’d climbed just enough to exceed my reach, had I wanted to slow here down.
The Blue Angels circled Hawk Hill several more times during the show, always maintaining formation while setting up the next stunt. I found that I no longer enjoyed their incursion into the airspace of Golden Gate National Park, now that I was watching them through the eyes of a frightened, juvenile sharp-shinned hawk.
Journal of Natural Hist. Ed.
Natural History Institute
Center for Humans & Nature