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Some birds, mostly males, have ways of slightly changing their looks, whether to attract a mate or aggressively mark their territory. One such species is the Red-winged Blackbird, a fairly common blackbird with red badges, or epaulettes, on its shoulders. You can often find these birds in large numbers around wetlands areas where they feed and nest. Adult males of the species are easy to identify because they are all black with a red badge on each shoulder, and sometimes a strip of yellow below the red.
I’ve observed these birds for years, and I was under the impression that some have much larger and bolder red epaulettes than others. I thought perhaps it was related to age, or just genetics. I’d seen some birds with very little red, whereas others had large, bold red badges. But it never occurred to me they controlled how much red was visible, even though it’s obvious when looking back through these photos.
I’ve recently been reading a fantastic book about the coloration of birds, titled National Geographic Bird Coloration, by Geoffrey E. Hill. It was here I learned about what is referred to as coverable badges, how some birds are able to cover their strongly colored feathers. The example he used was of Red-winged Blackbirds, and he described how they have a set of black feathers above their red epaulettes, which are the bold red patches of feathers on their shoulders. They are able to cover the red with these overlapping black feathers.
The red epaulettes of Red-winged Blackbirds can be used to attract mates and mark their territory. Hill describes how a male displaying its red epaulettes within the territory of another male is a very aggressive action and one often met with conflict. So the males need to display their red to attract a mate, but may want to hide their red when flying through another males territory. I suspect another time they may hide their red is when gathering nesting material, as may be seen in the photograph below. If a male will be flying back to its nest, I would imagine the last thing it would want is to reveal the location to another male.
In this post I show several examples of male Red-winged Blackbirds showing and hiding their red epaulettes. In some examples you can see they not only control how much of the red is showing, but can also actively puff out the red so it stands above the black feathers. Look closely and you can see they even sometimes push their shoulders out, bringing more attention to those bold, red badges of courage.
To learn more about bird coloration check out the book, National Geographic Bird Coloration by Geoffrey Hill, who is an ornithologist and professor of biology. Though intended for a broad audience, this book contains a huge amount of detailed information sure to excite anyone interested in ornithology. It’s not a quick and easy read, nor a college text book, but instead manages to tread that line between the two. I am absolutely loving it!