The prospect of diet being the key component in pink body feathering
leads me to this train of thought - the two species most commonly thought of
for "pinkness" are the Roseate Tern and Franklin's Gull. They typically
winter to our south. Typically in most birds, their body feathers molt in
January - April, prior to breeding, giving us the "breeding" or "alternate"
It is well known that the pink coloration of the feathers bleaches out
due to exposure to the sun - thus the birds "lose" their coloration as time
passes. A friend that once spent a season banding Common and Roseate
Terns on the nests commented that he could still find traces of pink on the
breast and belly feathers of nesting Roseates when they were held in-hand,
but that the same birds standing back by the nest showed no pink.
Since the feather molt is probably triggered by the lengthening daylight
of the new year, the birds' wintering range may be host to a "bloom" of
shrimp or crustacean that kicks in at just about the time that body feathers
are being replaced. Who knows, the shrimp bloom might be the trigger for
the change in the bird's metabolism. The actual molt sequence takes a
remarkably short time (I once photo-documented a Black-headed Gull that went
from "winter" head color to "breeding" head color in 12 days), so
binge-feeding on a shrimp bloom should be enough to create pink feathers.
Since flight and tail feathers only are replaced once a year, usually after
the breeding season, they are likely unaffected by the change in diet.
My two cents,
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----- Original Message -----
From: "tom curtis" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, March 28, 2005 4:02 PM
Subject: [FLBIRDS] Pink terns
> regarding the quote
> "A pink bloom can occur in all gulls except the 'large white-headed' ones,
> as well as in most
> Sterna terns. It seems to be induced by dietary components, but must be
> hormonally mediated as it occurs only in the breeding season."
> While I agree that the above quote is likely correct, there is still a
> possibility that the dietary factor responsible for the coloration is
> seasonally available. Thus, although the coloration is associated with
> breeding season, it might not be hormonally mediated. Up north we got
> "Orange-breasted" Chats and waxwings with orange tails, but only if a
> certain plant was fruiting when the young were growing feathers.
> One report available over the net
> found the pink coloration in an Elegant Tern in mid-September, well after
> the breeding season.
> Have fun,
> Tom Curtis
> [log in to unmask]
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