Long Migrations Make Drab Warblers 'Dress Down'
We all know that it's hard to keep up appearances when you're constantly on the go. That's why the fashion police will probably give some female warblers a free pass, even after researchers found that they boast drabber feather when their migration routes are particularly long.
The idea that female birds are drab while males stay vibrant is not exactly a new concept. Cardinals are one clear example of this phenomenon, with males boasting their startling red feathers even in the dead of winter, when they would be most visible in a snowy environment. Female cardinals, on the other hand, wear dirty whites and browns, blending right in with their drab environments regardless of the season. (Check out a rare "split sex" cardinal that shows how very different these plumages are here.)
The reason for this is that while males want to be seen in order to find a mate, it is best that females -who are essential to keep a species going - do not draw too much attention to themselves, lest they attract predators as well.
However, for many species females too remain relatively vibrant, especially among many song birds. Experts have long theorized that this is because boasting some vibrancy can help a lineage - where genes from a vibrant father and mother will ensure that their male offspring is dazzling enough to land a mate. (Scroll to read on...)
So why then, are migrating warblers so drab? Don't they want their sons to get hitched?
In the past, experts theorized that this may simply have to do with the length and nature of a breeding season, but according to a new study recently published in the Proceedings of the Royal Society: B, it's really all about pit stops and travel destinations.
Researchers at Trinity University in San Antonio, Texas, studied the coloring, migration patterns, breeding locales, and ancestry of 109 warbler species - including far-traveling northern migrators and local species who generally stay in one play year-round.
They found that as a rule-of-thumb, local warbler species had more 'fashionable' females compared to the drab migrators. The reason, the researchers then concluded, was because migratory species have more and varied predators to worry about, compared to local species. This led them to value safety over a mating advantage - perhaps a fashion faux pas, but one that keeps their lady-birds living.
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