One hypothesis bandied about some years back was that this mutation might
provide some selective advantage by virtue of its Jaeger mimicry.
Heermann's are kleptoparasites, after all.

Gene Hunn.

On Fri, 17 Nov 1995 JLRosso at aol.com wrote:

> Alvaro Jaramillo wrote
>
> Several days ago I saw a partial albino
> male Red-winged Blackbird showing white on the throat, part of the face and
> upperbreast. However, the white was strongly tinted pink. Dennis (remember
> him?) had mentioned that this was the norm in albino Red-wings, they usually
> show a pink wash to the throat and breast. The implication here is that all
> Red-wings have red pigments that are masked by the black of the underparts
> which only become visible when these dark pigments are not present. Traits
> that are not visibly expressed like these are ones that can really stump
> people when they do get expressed through some unusual situation like
> hybridization.
>
> Is this the same explanation for the group of Heerman's Gulls usually seen
> south of Monterey who all show a rather large white wing patch? I have never
> heard a good explanation of what causes that. When I lived in California I
> saw these birds often.
>
>
> Jim Rosso
> Issaquah
> 206-392-8440
>
>
>