Tuesday, April 21, 2009

Dark buteos

Today was really an excellent day for honing one's hawk identification skills, especially on the buteos. Think about it: it's the second half of April, so redtail and roughleg are regular sightings, redshoulder is still around, and two more buteos are now a possibility: Swainson's Hawk and broadwing. The latter, incidentally, is really a slam dunk guarantee when the next warm front pushes through, on Thurday. The way things are looking now, Thursday, Friday and Saturday should have south winds and higher temperatures, and that almost certainly means large numbers of broadwings. These birds are literally on our doorstep now. Braddock Bay, on Lake Ontario, for example had 2,600 today.

And Swainson's Hawk is a distinct possibility too, although obviously not in the same numbers.

I saw several dark morph buteos today, and not all of them were Rough-legged Hawks. Truth be told, lighting conditions were so poor that practically all raptors looked dark. Plumage details like belly bands, patagial bars, color of the remiges (never mind tail!) were invisible on all but the closest birds. That's why today was such a wonderful day for honing one's hawk ID skills.

Before I tell you which bird that is at the top of today's entry - and why it is that species and no other - let's do a little ID quiz, see if you can identify it. If you click on the photo, you might be able to make out that this is a dark morph buteo of some kind. As I said, lighting is poor but the body feathers and underwing coverts do seem a shade darker than the rest of the bird.

Here's another dark buteo for comparison, also photographed today:

I counted 105 raptors today, a modest number for this part of the season. Tomorrow might not be much better, but as I said, Thursday through Saturday (and hopefully Sunday) should see a significant increase in hawk numbers, as conditions change from unfavorable to quite favorable.

I hope you have worked out the ID challenge by now, because Swainson's Hawk is not on today's tally, so neither of these dark morphs is a dark morph Swainson's. (And they're not dark morph broadwings either.) What I did see today were 2 Turkey Vultures, 1 Bald Eagle, 3 Northern Harriers, 56 Sharp-shinned Hawks, 30 Red-tailed Hawks, 12 Rough-legged Hawks, and 1 Golden Eagle.

Two buteo species then, redtail and roughleg. The top bird is a dark morph redtail. It is in fact the same individual I posted a photo of two days ago, identifiable by the abrasion in its right wing. But why is this a redtail, and not a roughleg? Look at length of the tail and at wing shape, and compare that to the same qualities in the second bird - you've guessed it, a roughleg. See how different that bird looks?

Note the relatively 'short hand' on the redtail versus the 'long hand' on the roughleg. Note the short, straight tail of the redtail versus the longer, slightly flared-out, more rounded tail of the roughleg. It would have been ideal if I had a shot of both birds in exactly the same position, for that would have shown a greater bulge on the trailing edge of the redtail's wing, compared to that of the roughleg. It's visible here too, but it's difficult to compare that feature on birds in slightly different postures.

Dark morph broadwing is relatively rare, and the shape of a broadwing is very different from either one of these birds, with its rather short, pointy wings and a thick neck, a stocky bird overall. Swainson's Hawk is perhaps closer in shape to Rough-legged Hawk, but its shape is somehow more curvy, with more fluid lines.

The dark morph redtail (technically an intermediate morph, see discussion here two days ago) was not alone today. There was also a pitch black adult dark morph redtail in the flock. With both these westerners around, and several light morph redtails that look suspiciously 'western-like', I think our chances for Swainson's Hawk are actually pretty good at the moment. It's also that time of year... I would not be surprised to get that bird before the end of the week.

1 comment:

  1. EXCELLENT!! thanx SO much for the little 'quiz' on the ID of those two birds!! I have trouble telling them apart even on a sunny good day!! Your commentary is the first place i hit on the computer each morning and it helps me begin my day with excitement and anticipation for when i can get out to the point in person-also-with only a limited time to get out for birding these days, I very much appreciate your tips on when will be best weather/conditions for when the big flights might happen-NOW i can plan a trip for this weekend-this truly is the BEST way to end the long dark winter-by going outside and watching the birds!!
    thanx again-such valuable [and FUN] work you guys do out there!!
    Kathi in Brimley