When I last posted, we were gearing up for migration peak. Peak is a week or two when the raptors move in concentrated numbers over the headlands, and is the time when both Hawkwatch and Banding report their highest numbers. People at GGRO talk about Peak with excitement, anticipation, and an almost nervous energy. I’ve had multiple volunteers tell me that I won’t fully understand the work we do at GGRO until I’ve seen Peak.
Unfortunately, Peak is a somewhat elusive concept. Over the years, our director Allen Fish has put together all sorts graphs charting out average raptor numbers at certain dates over the years, and the Peak has stayed fairly steady around the end of the September. However, 30 years of data averages out a lot of unpredictability. It turns out that predicting the high point in advance is very difficult, as is recognizing it when you’re in the middle. Peak this year certainly hasn’t gone exactly how people expected it to, and we aren’t sure if it’s over yet or not.
Instead of a full week of consistently high numbers, we’ve had a handful of random high days scattered across the past two weeks. There was a storm front that hit the headlands right in the middle of the predicted peak, so it’s possible that that’s what disrupted it, but the reality is that we know very little about what actually controls bird migration, so there are a lot of different theories about what might be responsible: maybe the drought made it more difficult for birds to build up food reserves to migrate at the usual time, maybe there was a different weather pattern north in Canada that influenced birds farther up the migration “pipeline,” maybe birds are shifting their nesting date which would also move their migration date, or maybe it’s just random chance.
Luckily, I happened to be on our peak Banding day, as well as our highest Hawkwatch day so far. Up to that point in Banding, I hadn’t been in a blind with more than a few raptors at once, and I was worried that I wouldn’t have the experience built up to deal with a rush of birds. We caught 36 birds on our Peak day, and it was such a whirlwind that I quickly lost count. I definitely appreciated what training I’d had, since it allowed me to not be as stressed as I could have been. The pace itself was not so insane, but the care needed to make sure we still got adequate data on each bird but didn’t stress it out by holding it too long was a careful balancing act between speed and accuracy that made everything feel urgent.
Our Hawkwatch peak was similarly frenetic, especially early in the day. In a strange way, it reminded me of the whirl of energy that happens in a newspaper editing room the night of publication—everyone running back and forth, hurriedly yelling important data, trying to keep track of all the moving pieces while hastily putting together a finished collection of information. My identification skills had to keep up with the fast stream of birds, and I didn’t have as much time to sit and ponder all of the characteristics on each bird in front of me, I just had to trust in my own abilities and go for it (or make a quick judgment call and say things like “unidentified accipiter” if I couldn’t decide between Cooper’s Hawk or Sharp-Shinned Hawk).
I have been very lucky in both Banding and Hawkwatch to get to see and handle some of the rarer birds for this region. We’ve seen a good number of Ferruginous Hawks from the hill, which are very large, light buteos (the group of raptors that includes the bigger birds with large, dark-tipped, squared-off wings, like Red-tailed Hawks). When you see them coming head-on, they just look like a giant white V. We’ve also had some Swainson’s Hawks (another, much darker buteo) fly right over the top of the hill. In Banding, I’ve held multiple Merlins (an adorable little falcon that flies so fast they are notoriously difficult to catch). I was extremely lucky on our peak day to process a Red-Shouldered Hawk, and the season’s first Broadwing Hawk. Both of those are smaller buteos, the Red-shouldered with gorgeous dark reddish colors, and the Broadwing with a very light underside and more squat proportions.
However my favorite so far was the juvenile female Northern Harrier. Harriers (historically called Marsh hawks) are very unique raptors. Allen likes to describe them as the Frankenstein of raptors: take an accipiter tail, add buteo wings, and an owl face, and you get a harrier. They have a strangely stretched appearance to them, and they can ghost so close to the ground that they seem to appear out of nowhere. They hunt the contours of the land looking for small mammals, and they use their disk-shaped face to help them hear the scuttling of voles in the underbrush before they pounce down with their long legs. When I held the one we caught up close, her face was so beautiful, with rich dark browns and red. Her body was smaller than I had imagined—the wings are so large they give an inflated sense of size—but her legs were far longer than I expected. It was so special getting to release her and watch her fly away.
Shorter Bird Notes:
A large portion of the raptors that migrate through the headlands are Cooper’s Hawks and Sharp-Shinned Hawks. These are both Accipiters, which is a genus, or grouping of species, that also includes Northern Goshawks, although I have yet to see one of those out here. They are compact raptors that hunt with a focused tenacity that actually makes them look a bit silly. As is true for most raptors, the females are larger than the males. For Cooper’s Hawks and Sharp-Shinned Hawks, the difference can be quite large. So although the “Coops” tend to be larger than the “Sharpies,” there is some size overlap (at least on the West Coast). This, combined with their extremely similar shape and coloration, makes them very difficult to identify. In the end, much of what I learn on Hawkwatch is new tips for how to tell them apart, and for a beginner, I feel pretty good about my progress. However, they are very, very good at trying to trick us.
The day after the storm front moved over the Headlands, we had an explosion of termites. Definitely not as large or as numerous as the ones we had in Kenya, but it was cool to see that even here, the insects work on their own rhythm. Hawk Hill was covered with them during Hawkwatch as they spilled up out of the moist soil, but I was surprised at how few other animals I saw turn out to eat them.
People don’t appreciate Turkey Vultures enough. A lot of volunteers at GGRO scoff at their designation as raptors and the fact that we collect data on them at all. As I’ve mentioned in a previous post, “raptor” is a fairly loose term that originally had more to the do with the look and loosely defined behavior of a bird than its genetic relatedness or diet. However, vultures share many convergent characteristics with other raptors, such as hooked bill and talons, and they eat meat. More importantly than just how they are classified, vultures play an incredibly important role as scavengers. Their scientific name, Cathartes aura, means purifier. They have some really interesting adaptations for locating and consuming carrion, such as an impressive immune system and incredible sense of smell. Unfortunately, Turkey Vultures, despite being common and extremely widespread from Canada to the tip of South America, are not invulnerable to the impacts of humans. Because they can often live close to humans and agricultural areas, they tend to accumulate pesticides and other contaminants like lead shot or poison from baited carcasses. They are also often fall victim to (mostly accidental) collisions, electrocution, trapping, and shooting. They are also the most common bird to get hit by an airplane. Thankfully, most intentional efforts to eradicate vultures have ceased, and their numbers have been increasing in the past fifty years, so now we just need a few more people to recognize how cool these birds really are.