What signalling advantage would a black belly give to a ground-hugging
bird like a longspur?

Gene Hunn.

On Thu, 21 Dec 1995, Kathleen Hunt wrote:

>
> Hi -- Well, even though the CCLO hasn't been seen for a while, here is a
> bit more info from the Burke Museum. I went up there today (actually I'm
> typing this from there) and got quite carried away with hypotheses of
> evolution of molt & color in longspurs. But anyway, the Burke has just 5
> CCLOs, 3 males and 2 females. The 3 males are all dramatically colored
> breeding birds, so they're no help. One female is a summer bird (17 July)
> and she indeed has a very dark breast & belly. The color isn't pure black
> (as it is on the males), more like dark chocolate brown, but it'd probably
> look black in the field. But the other female is a WINTER bird (12 Nov)
> and she is completely pale all over -- no dark patch at all on her breast,
> just some faint brown streaking on a pale buffy background. Each
> individual breast & belly feather has a very long buffy tip, with about a
> full centimeter of buffiness to wear away before the chocolate brown base
> would show through.
>
> So our Montlake Fill CCLO had a far darker belly than does the Burke's
> only winter female, and thus I vote for male. I wish I had more winter
> specimens to look at, though -- a sample size of one doesn't really fill
> me with confidence!
>
> Interestingly, 3 of the 4 longspur species have a black breast patch that
> develops by wear of pale-tipped feathers, & all 4 have a black crown
> that develops the same way. The Lapland then supplements this with a
> spring molt of black chin & cheek feathers. The Smith's is the only one
> without the black breast patch (also the only one with no chestnut
> anywhere). But I digress.
>
> cheers,
> Kathleen
>
>