Montana Tales and Trails

Some of the hardest questions to answer start with why.

Why will fish bite one day and not the next, or even stop biting when they were having a feeding frenzy a minute ago?

Why did prehistoric people use a particular cliff face to draw a petroglyph?

Why can't I win the lottery? Okay, scratch that.

Just the other day, an acquaintance asked why magpies are black and white. First, magpies are not just black and white. Their colors include shades of gray, green and blue. In the right light there is a beautiful iridescent sheen to their dark feathers. If the question is why do magpies look black and white, we should start with how animals use color in nature.

Animals generally have color for one of two reasons: to avoid detection, think camouflage, or to attract a mate. Yes, there are exceptions, like those creatures that are toxic and proclaim it as a warning for all to see. But they are the minority.

Avoiding detection can serve two purposes, depending on whether the animal is a predator or prey. Members of the wild cat family such as mountain lions, bobcats and lynx, combine their mottled colors with stealth to sneak up on an unsuspecting critter. That unsuspecting animal, however, tries to avoid said predator by blending in with its surroundings. There exists many examples from a female duck on a nest to rabbits to the lowly field mouse. Even fish will have a dark back to escape a predator from above, either fish or avian, and blend in with a stream bottom or the blackness of deep water.

The opposite of using color for camouflage is using color for breeding. Typically, the males of many bird species are gaudiest in the spring as they flaunt themselves shamelessly. Male animals may use other mating methods like bird songs, mammalian antler size, or fighting for dominance. But coloration might be the easiest for humans to recognize.

According to the book "Bird Feathers" by S. David Scott and Casey McFarland, colors come from a bird's pigmentation or the structure of a feather. Sometimes both in a single animal.

Pigmentation has three types: melanin, carotenoids and porphyrin.

Melanin is responsible for black, gray and brown feathers.

Carotenoids produce brilliant reds and yellows and are mostly on body feathers. The interesting part is carotenoid pigments are found exclusively in plants, not birds.

As "Bird Feathers" states: A northern cardinal eats bright red berries and the pigments are processed in the liver, delivered to the bloodstream, then transported to a developing feather. If lacking these carotenoids, a cardinal will lose its vibrant coloration.

Porphyrin pigment produces pinks, browns, reds and greens. Porphyrins are made in the bird's body and is not affected by its diet.

The other factor in color production comes from a feather's structure. For example, blue, like in a blue bird, does not originate from a pigment. Rather, the structure of the feather scatters light waves sending only the color blue to the observer.

Back to our friend the magpie and other iridescent birds, bits of the pigment melanin in their feathers act like tiny reflectors, scattering different wavelengths of color like a prism.

So next time you see a magpie, give it a tip of the hat for its coat of many colors.