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Re: skin decoration Vs feather decoration in predatory archosaurs



For what it's worth, some sea eagles (the bald eagle and Steller's sea eagle) while not exactly colorful, are quite striking for raptors, the bald with its yellow beak and feet and white head contrasting with its dark body, and Steller's with its blue-grey plumage and orange beak and legs. The caracara of central and South America is also very colorful I think that may have been mentioned before.)

-M. Nalasco

From: Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>
Reply-To: tommy.tyrberg@norrkoping.mail.telia.com
To: martin.barnett3@virgin.net, <dinosaur@usc.edu>
Subject: Re: skin decoration Vs feather decoration in predatory  archosaurs
Date: Thu, 13 Apr 2000 20:17:49 +0200

At 03:39 2000-04-13 -0700, Martin Barnett wrote:

The bateleur and the gymnogene among others have bright red skin on their
faces. This is actually not that uncommon among raptors. Certainly there
are raptors with blue (or at least blue-grey) legs, the Gyrfalcon for
example, in old times  was also known as "blåfot" (bluefoot) in Swedish,
brigt yellow skin is much more common though. Furthermore vultures hardly
qualify as raptors, they specialized scavengers and do relatively little
hunting for themselves

I can add a few plumage colors:

blue-gray (fairly common, e g male Harriers)

rufous (also fairly common e g kestrel and related small falcons)

chestnut/orange (breasts of some Accipiters and falcons)

Note that there is one completely and one almost completely white raptor
(light phase of Variable Goshawk (Australia) and White Hawk (Central
America)), some Icelandic and Greenlandic Gyrfalcons are also nearly white.
I've been lucky enough to see all three and they are all extremely striking
birds. How about white theropods in Australia/Antarctica?

There is no green, bright blue, bright red or bright yellow plumage in any
raptor.


Tommy Tyrberg



> I noticed that all the birds' feathers (with the possible exception
>of Pernis aviporus, the honey buzzard) were of the following colours:
>Black White Grey-scale Anywhere within the brown spectrum
>between peach and terra-cotta It was interesting to note that any with
>bright colour had it in their eyes or on their skin The following colours
>were noted on the skin: Token example Accipiter nissus (sparrowhawk)
> with Gyps fulvus (griffon vulture) to more "mother-of-the-bride"
>shades, ie, Falco vespertinus (red-footed falcon) Found in Elanoides
>forficatus (swallow-tailed kite) among others. Orange? - Neophron
>percnoterus (Egyptian vulture) picture is a little unclear, could be a
>solarised yellow. I also recall (from memory, so beware!) seeing a
>raptor with blue feet. So, the overall trend with at least modern
>feathered archosaurs is for camouflage colours using pattern for display
>on the plumage and actual vivid colours when present on the skin.
>Daspletosaurus with blue legs) Sam



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