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What's wrong with this RWBB?


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THis adult male Red-winged Blackbird was seen two days in a row last week at St. Mary's Island WMA in western Iowa.  I'm not suggesting the bird is sick or injured.  Just want to know why the unusual throat markings and what that type of marking is called.  Partially leucistic (spelling)? 

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It might just be a very old female that has lost so much female hormone that it's expressing male plumage. The peach colored throat is a feature of adult female Red-wingeds. In birds, unlike in mammals such as ourselves, male is the default sex. That is, male is the homozygous sex, rather than female, which is heterozygous. That means that female hormones override the expression of male plumage characters in female birds. When those hormone levels drop below some threshold, male plumage features can begin being expressed -- that is, not overridden. However, I believe that soft-parts coloration, if they differ between the sexes (such as in Bushtit and most ducks), is not affected, as the soft parts are not replaced.

Whatever the cause, that bird is COOL!

Edited by Tony Leukering
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5 minutes ago, Tony Leukering said:

It might just be a very old female that has lost so much female hormone that it's expressing male plumage. The peach colored throat is a feature of adult female Red-wingeds. In birds, unlike in mammals such as ourselves, male is the default sex. That is, male is the homozygous sex, rather than female, which is heterozygous. That means that female hormones override the expression of male plumage characters in female birds. When those hormone levels drop below some threshold, male plumage features can begin being expressed -- that is, not overridden. However, I believe that soft-parts coloration, if they differ between the sexes (such as in Bushtit and most ducks), is not affected, as the soft parts are not replaced.

Whatever the cause, that bird is COOL!

thats a great theory Tony, I have headed of that but I totally forgot in till now, agree that the bird is awesome!

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