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Thread: Swainson's Hawk?

  1. #1
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    Default Swainson's Hawk?

    Please excuse my uncertainty. I'm new to birding and bird photography. Going by my old copy of "All the Birds of North America", I'm thinking this is a Swainson's Hawk intermediate form. There was a pair on adjacent poles, with what I took to be an immature (looking a little beat up) on a third pole. I got pictures of all, but had to shoot into the bright sky hand-held, so maybe not as steady as I'd like. Added a little canvas above and to the left, and removed some wires just under the bird.

    Shot with Nikon D7000 and Nikon 200-400 f/4 with Nikon 1.7 TC @ 650mm, f/6.7 @ 1/200, distance 29.9 meters.
    Image taken 7/30/2011 at 8:02 am in Lehi, Utah.Name:  _R006887-Swainson's-Hawk-10x15.jpg
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    Hi Ron- Big welcome to BPN. Nothing to excuse, bird ID is often difficult, as my many errors attest! I would say this bird has the plumage features of a young, dark Swainson's and the location is correct. There are quite a few raptor experts at BPN who will no doubt chime in.

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    I'm not one of the raptor experts John refers to, but to me this is a Swainson's hawk.
    John, would this not be an adult as there is no mottling of the breast patch?

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    You are one of the people I was thinking about Roy!

    This is very much an armchair exercise for me because Swainson's don't show up very often in the east. Referring to Sibley, he illustrates juvenile and adult Light, Intermediate, and Dark forms/phases. To me this bird doesn't look like any of the illustrations (!), and I take back my original suggestion because I now see the very light underwing patches in this bird, which according to Sibley only the Light and Intermediate forms have. If the bird is an adult it can't be a Light form because of the dark belly. That leaves intermediate but the face on this bird is no where near as white as illustrated so perhaps it's a youngish bird developing its adult plumage.

    Having said all this, maybe there is so much variation in Swainson's (as there is in other Buteo hawks) that almost anything is possible.

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    John said "Having said all this, maybe there is so muchvariation in Swainson's (as there is in other Buteo hawks) that almost anythingis possible." Very true!

    Two things about this bird suggest adult to me, the ware onthe wing coverts and the very bright yellow cere.

    My limited in hand experience banding raptors automaticallymakes me look for uneven ware to help age them. Adults usually have older moreworn feathers present. Birds of the year have very uniform feathers.

    As for the picture except for the angle I personally thinkthis is an excellent image of a Swainson's Hawk.

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    Thank you all, sincerely, for the extended discussion. I went back up there yesterday morning, and found the two adults present, but the young one nowhere to be seen. If it's of any interest, I would be happy to post the juvenile's picture tonight when I get off work.

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    For sure Ron, would love to see a young one.

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    Ok, here's the young one. I thought when I first saw him that he was being beat up by the adults, but when I came back a couple days later he was on the same post (sitting down, if that's the right description) while the adults hunted. It made me think that he was just fledging the first day, and maybe not too successfully. Could that be the case?

    Pardon the hardware and BG in this one. I had to shoot right into the sun, and couldn't get a clean shot without the wires.
    Nikon D7000 and 200-400mm f/4 w 1.7 TC in aperture priority +2 EV
    f/6.7, 1/200, ISO 1100, 650mm, distance 15 m

    Name:  _R006865-Ruffled-Swainson's Hawk Juv-Nat-Size.jpg
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Size:  138.9 KB

  9. #9
    Dave Irons
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    As some have suggested, this appears to be an adult intermediate Swainson's Hawk. One thing to consider if you think you are seeing a Swainson's is wing length. Like other long-distance migrants -- most Swainson's vacate N. America and fly to S. America to winter -- is they have extremely long wings. In the shorebird world, Buff-breasted Sandpipers and Baird's Sandpipers make a similar annual loop. If you see them standing, their wingtips extend well past the tip of the tail. Similarly, the wings of Swainson's Hawks are proportionally longer than those of other Buteos. It is clear that the wingtips of this bird reach beyond the tail. Most other North American Buteos are much shorter distance migrants, if they migrate at all, thus their wingtips (when perched) come up short of the tip of the tail.

    Dave Irons
    Last edited by James Shadle; 08-19-2011 at 07:16 PM.

  10. #10
    Dave Irons
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    Please note that my post is referencing the first of Ron's images and not the second, which is an immature Swainson's Hawk.

    Dave Irons

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    Thanks Dave. I am not aware of any science specifically supporting the idea that wing-length alone is correlated with migration behaviour but it's an interesting idea. There are plenty of examples of closely related species that have very different migration patterns yet have roughly proportionately similar wing lengths (e.g., Common and Arctic Tern). There is scientific support for the idea that wing shape (aspect ratio) and wing loading (wing area divided by weight) are related to different flight performances and different modes of flight.

  12. #12
    Dave Irons
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    Not sure if there is any hard science, but if it's just a coincidence it seems to be one that is pretty prevalent.

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