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Re: two questions
Hi all,
There are many other gulls shows that pink tinge on white breast and belly, like
Black-headed, Slender-billed, Ross's and Little Gulls ( I know and seen).
The other explanation of that coloration is that, some gulls eat more crustaceans
(like small Gammarus spp.) than the others if they are lucky to be in the area with
thousands of these small animals. So that pinkish color comes from crustaceans
carapax. That is the same story as in case of Flamingos, they become more and more
pinkish if in the diet are more and more crustaceans. If there is no such a food
birds become more whitish (see many Flamingos in some Zoo).
Mike
Donna Bailey wrote:
> Linda -
>
> Although I am no gull expert, I had reason at one point to research the pink
> blush that is sometimes reported on the undersides of gulls and terns. As I
> understand there are a couple theories about the pink in the breast.
>
> The first theory is that the brood patches of these seabirds is so densely
> covered with blood vessels that the pink shows through the white feathers.
> I've seen brood patches on a couple of larger songbirds in the hands of banders
> (Brown Thrasher comes to mind first) and I can see where that might be possible.
>
> The second theory is that the oil secreted by the uropygial gland at base of
> the tail of these seabirds is pink, the oil itself is pink. Depending on the
> density of the layer of oil on the bird and the vigor and consistency with
> which the bird has been preening, a pink cast or blush could be visible on the
> feathers, especially the white feathers of the breast.
>
> Also keep in mind that being a bird, especially a seabird, isn't the cleanest
> job in the world. The bird could have been stained by some foreign substance
> like blood in the water at a feeding site.
>
> So the answer is many of the gulls and some of the terns can and do
> occasionally show some pink on the breast. Some have more of tendency to do so
> than others (apparently Franklin's gull and I think Sabine's Gulls are reported
> to have a pink cast in breeding plumage sometimes, as well as, of course,
> Roseate Tern).
>
> Hope this helps.
>
> Donna Slyce Bailey
> Winnsboro, SC
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