butter butt

•



We only have a few more weeks of desolate winter to weather before the coming of vibrant spring. 

I find that by this time of the year, I long for color. The grays and browns of winter start to wear on me and sometimes just the briefest flashes excite.

Example: a species of warbler that spends its winter here in the valley, the yellow-rumped, spends it in its dingy winter plumage, that is except for its namesake bright "yellow rump."

Joy Baker recently captured one with her camera. And even though it is a ho-hum color, her photo (above) shows that its "butter butt" shines for all to see.

In a few weeks, Joy's warbler will migrate north to New England and the provinces of Canada where it nests. 

Breeding plumage Photo:wikimedia

It will also molt into its more dramatic breeding plumage (left), shedding its winter drab. But the yellow rump stays bright.

I understand why they molt into bland plumage to better blend into the dull winter background, and the intense contrasting colors of spring to attract a mate.

But here is the question: Nature is enormously practical, why keep the bright yellow rump in winter? To what purpose? Doesn't it make them more noticeable to predators like sharp-shinned and Cooper's hawks? 

To what advantage the butter on thy butt?

Thank you for the use of the photo, Joy.  

•