The Natural History of Dark-Phase Hawks

I wish I had photos to illustrate this post, but I don’t, it’s just something that’s been on my mind.

I’m not sure I’d ever laid eyes on a dark-phase Red-tailed Hawk before I moved to Eastern Oregon. Now I see them all the time. (At first, I’m embarrassed to admit, I think I mistook a few of them for Golden Eagles. Western raptors are still a new thing for me.) Click here for a photo of a typical Red-tailed Hawk, and here for a photo of the dark variety. Same species, two very different-looking birds.

A number of other Buteo raptors also have dark and light morphs – Swainson’s Hawks, Rough-legged Hawks, and Ferruginous Hawks are all found here and all include both dark and light birds. This variation is genetic (think of hair color in humans), and while dark birds are generally less common that light birds in every species, this varies by geography – you’re more likely to see a dark Red-tailed or Ferruginous Hawk out west, more likely to see a dark Rough-legged Hawk back east. What I want to know is, why? Is natural selection at work here, and if so, how are different color morphs adaptive for different regions? Continue reading “The Natural History of Dark-Phase Hawks”

Ferruginous Hawk

It’s Sunday afternoon. You realize it’s been a week and a half since your last natural history blog post. You don’t feel like going on a long expedition. What do you do?

Luckily, I live somewhere where I can grab my camera and long lens, pick a direction, drive for ten minutes, and find a subject for a blog post on the side of the highway.

002 (730x1024) 005 (733x1024)As is the case throughout most of North America, our most common roadside hawks here are Red-tails. This one, though, is something different. It’s not a species I see very often but I’m ninety-five percent sure this is a Ferruginous Hawk, specifically a light-morph juvenile. The pale unmarked underside and face and the feathered legs set it apart from the Red-tail, Swainson’s, and other buteos we might expect to see here. I was first introduced to this hawk, a classic grassland species, four years ago during the summer I spent on the Saskatchewan prairie.

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After humoring me for a minute while I snapped photos through the passenger window of my car, it took off into the evening. This was a new one for my year list – I’m sure I’ve passed Ferruginous Hawks while driving around here before, but this was the first time I stopped and looked closely enough to make the ID.