Do you see the bird in the photo, the brown and tan bird in the tall grass?
The bird doesn't want you to see it. Neither you nor predators.
Evolution has worked for a long time to perfect that protective coloration.
Actually, the work is never done. This bird, a willow ptarmigan, is a work in progress, as are all birds. Evolution is ongoing, always with an eye, so to speak, on the surroundings in which the birds live.
Evolution is adaptive. Change the background, change the bird.
The ptarmigan family is cryptically colored, this bird in brown and tan and black — camouflage for an animal in its natural environment. The Cornell Lab of Ornithology explains, "Individuals whose colors best meet their needs raise more young and pass to those offspring their favorable colors and patterns."
The earth tones of our sparrows best meet the needs of birds that feed on the ground. The colors are placed in stripes and streaks running the length of the body. The birds blend with the grasses and reeds they frequent.
That's the trick of the ptarmigan, blending into the grass of its habitat.
Bright colors — reds, blues, yellows — are important in courtship, such indicating a higher degree of fitness.
Those colors are not necessarily a problem when it comes to predators. Cats and raccoons, for instance, lack color vision. Ditto for owls.
It's different if a Cooper's hawk is on the hunt. Raptors hunting by day are believed to have full color vision.
Go back to the sparrows for a moment. Our yard attracts many ground-feeding birds that often choose to feed in shade when possible. They are less conspicuous there.
Nighthawks are another cryptically colored species. In their family is a bird named pauraque, found in Texas. It nests on leaf litter on the ground.
I once had a naturalist point to a pauraque not 5 feet from me. Where? Point again. The bird trusts its coloration so much that you would have to touch it to make it move. (Movement is always the giveaway.)
In addition to color, certain markings help confuse predators, according to Cornell. The two black bands on the neck of a killdeer disrupt its silhouette. The bird just doesn't look quite like it should.
Colored or white patches suddenly flashed when a bird takes flight can startle a predator, giving the prey a split-second more for escape.
Some birds have dark colors near their eyes. This is thought to reduce glare. It is more easily seen on football players.
A light-colored upper mandible — the top half of the beak — can reflect light, a glare believed to hinder foraging. Most upper beaks are dark. Studies have shown that warblers with dark upper beaks forage in sunlight more often than those with light upper beaks.
There always is a reason.
It's difficult to use color and markings to identify individual birds. Birds recognize conspecifics — individuals of the same species — as easily as you do friends or family. Color, markings, head and body shape, posture, all are clues.
There is a way to identify individual downy and hairy woodpeckers. There are (subtle) differences in markings on the top of their heads.
Cornell tells us that a northern pintail duck can recognize its mate from 300 yards. Can you?
Lifelong birder Jim Williams can be reached at woodduck38@gmail.com. Join his conversation about birds at startribune.com/wingnut.
