There are legions of bird watchers but not so many mammal watchers. Whale watchers are an exception. Many people put up bird houses, but only a few put up bat houses. You can purchase any number of field guides for birds, but your choices for mammals pretty much max out at two at bookstores.

There are legions of bird watchers but not so many mammal watchers. Whale watchers are an exception. Many people put up bird houses, but only a few put up bat houses. You can purchase any number of field guides for birds, but your choices for mammals pretty much max out at two at bookstores.

Why do birds attract so much more attention than mammals?

There are several reasons. Most mammals are nocturnal; most people are not. A hobby that requires you to run around with a flashlight at night chasing mice or skunks isn't for everyone. The singing of an American robin or hermit thrush can mesmerize. Squirrels aren't in the same choir. Then there is the dazzling display of color. What mammal can match the iridescent gorget (throat patch) of a hummingbird or the rich blue of a mountain bluebird?

Don't get me wrong. Mammals are fascinating, every bit as fascinating as birds. And yes, I have chased spotted skunks with a flashlight at night, but this column is about birds.

For all their beauty, many of the colors in feathers are less than skin deep. Grind up a hummingbird or bluebird feather and all you have is a brown powder. Many colors in bird feathers are the result of tricks involving the scattering of light. Other colors come from pigments, something a little more familiar.

Most reds, oranges, pinks and yellows are produced by pigments. Some pigments come from the breakdown of blood or bile. Others come from diet. A flamingo that doesn't get enough tiny crustaceans in its diet produces very pale feathers in contrast to the vivid pinks of those with a richer diet.

Now, check out the house finches at your feeder. The males are red. Some are a vivid red while others are duller. A few are orange and, rarely, you might even see a yellow one. The extent of color also varies. Some are red only in the line over the eye, the chest and rump. In others, half the body glows.

It is said that clothes make the man. In birds it is the man that makes the clothes. A male that is an efficient forager, healthy and eats well produces more and brighter colors. A weaker bird and one that is just getting by will be dull, pale and tend toward orange or yellow. Males have little ability to store up the raw material for colors before molt. Thus males can't cheat. The color they wear is an honest reflection of their quality, and they must wear their badge of shame (or pride) openly.

In the house finch world, the redder the better, and everyone knows it, including the females. Studies have shown females preferentially select the most colorful and reddest males for mates. A female that succeeds in pairing with one of these bright males finds him to be a better spouse and parent. He feeds the female more while she incubates and provides more food for the young, ultimately resulting in more fledglings. This means your feeder will tend to be filled with the showiest males. Not a bad deal.

Stewart Janes is a biology professor as Southern Oregon University. He can be reached at janes@sou.edu.