For birds, cleanliness is not optional. They rely on their feathers for flight and insulation, and only replace those feathers once or twice each year. In between molts, they need to keep their feathers as whole as possible.
Feathers, like our hair, are made of protein; and like all organic things, they degrade over time. Sunlight hastens this degradation, but certain aspects of the feathers themselves can slow it: dark feathers colored with melanin last longer in sunlight, for example. Of more concern, though, are the many creepy-crawly things that like to eat protein, and will happily hang out in a bird’s feathers, munching and laying eggs.
To combat these parasites, birds coat their feathers in protective oil from the preen gland located at the base of their tail, and they bathe.
But they have to be careful. Small wild birds are lunch for everything from feral cats to Cooper’s Hawks, and no bird wants one of these sneaking up on it while it is obliviously scrubbing behind its ears. So they bathe in bursts, a plunge into the water followed by a quick look around.
This Chestnut-backed Chickadee is molting his head feathers, hence the odd colors.
After breeding, if you’re a bird, comes molting. Time to discard those old, worn, raggedy flight feathers and start with some fresh ones for the long haul of the fall molt, or replace sparse downy feathers with good warm ones for the cold of winter. This means that around now—from mid-July to September—you may see a lot of birds who aren’t looking their best.
Birds need to know a lot about each other. They need to know things like who will be the best parent; who will pass on the best genes; who could defeat them in a fight; and which offspring is worth investing in the most. One of the ways that birds can perceive such information about each other is by observing each other’s color signals—and the more researchers study these, the more it becomes clear that birds can tell a lot from color alone.
Let’s make up a bird species – the Superb Junco. This imaginary species has a black hood and pink bill like the Oregon Junco, but its body and tail are iridescent blue-violet. Here is an illustration of three individuals of this species:
These individuals are clearly different: A has a paler head, B has a paler bill and is less brightly shiny, and C is brightly colored in all aspects. But what does that tell us?
When you’re little, you play with toy dinosaurs all bright red or blue or painted spotted with many colors. You fill coloring books with purple velociraptors taking down plaid apatosaurs. Then you get older and learn about camouflage; and you watch nature documentaries of brown felines taking down brown gazelles in tall brown grass; and—zebras notwithstanding—you start to think that probably dinosaurs weren’t plaid after all.
Well, buck up! They—at least some of them—probably did look really awesome.
We band it with the uniquely numbered US Fish & Wildlife band. This is the first priority because once the bird has this on, we can identify it later even if it escapes. Then we add the three colored leg bands so that we can identify it later even from a distance.