Friday, September 21, 2007

Sharp-shinned Hawk eye color

When I was at Hawk Ridge on Wednesday, the banding station sent four Sharpies to the main overlook at once so we could compare immature and adult plumages and see how eye color changes over time. First, here's an immature. Notice how yellow his eyes are, and the vertical streaking on the breast.
The next birds are all adults, with horizontal, rustier streaking. Over time, the eyes get orange and then red. The progression isn't a precise year-by-year evolution, but as birds mature, the eyes get redder.


This bird appears to be the oldest and so the most attractive to the opposite sex.
Quite a few species show changes in plumage and/or eye color as birds age. Mockingbirds and Brown Thrashers acquire new songs throughout their lives, and the more songs a male sings, the older and more experienced he appears, making him increasingly desirable for females. These clues about age give birds of the opposite sex a better picture of just how old, and thus experienced, an individual is. In nature, the more mature a bird is, the more attractive it is to the opposite sex, because maturity = experience = greater likelihood of successfully nesting and rearing young.

8 comments:

  1. Hi Laura-
    came upon your blog while trying to determine the color of Hawk's eyes. Many different kinds of Hawks with an assortment of eye colors?
    Or can you give me more specifics?

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  2. Accipiters--in North America that would be the Sharp-shinned and Cooper's Hawks and the Goshawk--start out with yellow eyes that turn red as they grow older. Falcons have brown eyes throughout their lives. Baby Bald Eagles have brown eyes which turn yellow as they mature. I haven't paid that close attention to buteos to know how they mature--the ones I've looked at have been rather brownish.

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  3. Hi Laura,
    Like Mary, I was searching for information about eye color and hawks. I snapped a photo of what I thought was a sharp-shinned hawk in a tree and noticed the eye color is light blue. I hadn't noticed something like that before. Is it unusual?
    Thanks,
    Aerie-el

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  4. Light blue would be extremely unusual. If you want to email me the photo to look at (I would never post it or use it in any other way without your permission), I could tell you for sure if that's what it is. chickadee.erickson@gmail.com

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  5. Hi,
    I stumbled accross y'all looking for info on hawk evolution....
    but if I could add:
    Accipiters start out with pale blue eyes that quickly turn yellow- barely out of the nest. That could explain your blue-eyed hawk.
    Buteos change too, usually yellow turns to brown at maturity but still getting darker with age.
    Aint nature grand?!

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  6. Now that's interesting! Thanks, Rockhopper!

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  7. I've had to restrict comments due to a really bad infestation of spam. But I got an email today (Feb 17) from Kevin Purcell:


    Cooper's Hawk fledglings have blue-gray eyes that they retain until around September of their first year (for 6 months or less). You'll see this if you can get close to the fledglings which is not that easy but possible in urban environments. I have a couple of photos of fledglings taken whilst banding them (in Seattle, WA) that show this feature.

    (Photo link should follow soon)

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  8. Kevin posted a photo of a sharpie with a bluish eye here: http://kevin-purcell.blogspot.com/2010/02/fledgling-coopers-hawks-have-bluish.html

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