From: "Kevin A.
Date: Mon, 23 Jan 1995 10:42:49 -0500 (EST)
To: Jessica Morton <jmorton>
Subject: Re: bright birds

Amanda and Jessica,

Great questions such as yours demand great answers, so I'll try my best to
make sense out of this tricky business. To my knowledge, no birds are
poisonous. So then why the bright coloring on ANY bird, and why do there seem
to be so many more in the tropical areas of the world?

To answer the last question first: well, there really aren't. If you compare
percentages of brightly colored birds to dull-colored birds in North America to
those percentages in Tropical American birds, the percentages are about the
same. This means that it isn't that there are so many more brightly-colored birds than dull-colored birds in the tropics; it means that THERE ARE MORE BIRDS OF ALL
TYPES IN THE TROPICS, and the increased number of highly-colored birds is
exactly what you would expect from a larger population.

Another reason we think there are so many more brightly colored birds in the
tropics has to do with advertising and television. Any time we are shown an
advertisement for a tropical hotel resort, there are usually parrots or toucans
involved. The same is true of printed advertisements for tropical places. On tours to tropical places, even bird-watching tours, the guides like to point out the more
spectacular birds rather than the dull, ordinary-looking birds. If you were to
take a trip into the heart of the rainforest, wouldn't you be a little disappointed if you didn't see all those "exotic" brightly colored birds? I know I would! Not many people want to spend a lot of many traveling to exotic places to look at "ordinary"-looking birds.

So why are birds so brightly colored anyway, no matter where they live? We
think there are several reasons. First, though, we need to realize that not all
birds in a forest live in the same place. Some live on the forest floor and
some live in the very tops of trees where they can touch the sky. Other birds live everywhere inbetween. This is called "stratification". This is important to the answer because in the majority of birds, their color is determined by their immediate surroundings, or what "micro-environment" they like to live in. Think of how a fawn's colors allow it to be nearly invisible on the forest floor; in the same way, many birds use dull coloring to hide from predators. A brilliant hummingbird wouldn't be invisible at all against the background of the forest floor, and so the hummingbirds living the dark lower levels ("strata") of the forest are dull-colored, not the spectacular ones we see in magazines and on television.

We've explained why it makes sense that a dull-colored bird, living low in the
forest, is dull. But why are the brightly-colored birds brightly-colored?
There are two reasons: mating, and hiding, just as before. Ornithologists
(people who study birds) think that bright colors, just like dull colors in some birds, make them very difficult to see. When you look up in the forest, you see patches of sunlight. If a bird has many different colors on it, it tends to break up the shape of the body, making it less recognizable as a bird. If you divide forest birds into groups based on where in the forest they like to live, you can see that the more brightly-colored birds tend to spend the most time in direct sunlight or bright light; that means up in the tops of the trees, rather than on the forest floor.

Some birds, like other animals, use bright colors to attract mates, even when
it means giving up their ability to hide. The best example of this is a small
low-level jungle bird called a manakin. All manakin species' males are
brilliantly colored, and are VERY OBVIOUS when seen against the background. They compensate for their inability to hide by being very fast! (They jump quickly from branch to branch, and it looks sort of like a pinball machine!) Also, when they court females with their incredible acrobatic routines (this is called "lekking"), they do it in groups of at least three in most species; more pairs of eyes watching for danger reduces the risk of being attacked by an unseen predator.

Coloration in all types of animals is a very interesting subject. It is
difficult sometimes to understand why things are colored the way they are,
because it is often difficult or impossible to find a way to test the idea. All
we are left with, if we can't use a test to answer our question, is to come up with ideas which sound reasonable, and that's really all we are able to do on the subject of coloration.

Thanks to Amanda for asking the great question! Keep watching and studying
those birds!

Happy Birding,
Kevin Akers
The University of Tennessee,
Knoxville, Tennessee.

Source: Birds of Tropical America, by Steven Hilty