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It’s in your nature: Why do some bird species have such differences in coloration?

Published August 31. 2019 06:41AM
by Barry Reed

Frequently asked: Why are most male birds much more colorful than the females? The question would be better asked: Why are female birds less colorful?

The terminology for this difference is called sexual dichromatism. This is the color difference between males and females of the same species.

A female bird needs to select who she feels will be the best male to mate with to ensure that her offspring will be the fittest to survive. She has two factors from which to choose. Which male is most colorful, or at least to her taste, or which male’s song gets and keeps her attention. Thus the “fittest” male will have been selected.

The duller colors of females are most evident in birds nesting in vegetation or trees, helping her to better blend in while on her eggs or returning to feed the young. She needs to be less noticeable to predators.

The bird utilizing sexual dichromatism most familiar to most of us is the cardinal. If the brilliant male were incubating eggs, it would be similar to a neon sign directing a nest raider to its meal.

Other than cardinals, the following are prime examples of sexual dichromatism: most duck species, scarlet tanagers, grosbeaks, buntings, finches, goldfinches and warblers, to name a few. You probably already know that a male mallard duck or wood duck are gaudy compared to their mates, and likewise their role in raising the young is nil. These “best-dressed males” have really only one job, and that is to breed.

Most birds that are cavity nesters show little variation between male and female. The cavity itself tends to protect birds from most predators accessing the eggs or young. Examples of these species include: most woodpeckers (flickers, downy woodpeckers, etc.) chickadees, tufted titmice, great crested flycatchers, and even our two nuthatch species, the red-breasted and white-breasted.

I hope the photos accompanying this column will help you with this topic.

Test Your Outdoor Knowledge: True or false Almost without exception, our local woodpecker male’s only difference from his mate is the amount of red on the head, face or nape.

Last week’s trivia: Bird migration is still not completely understood, but we do know that star patterns, earth’s magnetic field and landmarks all help them migrate.

Contact Barry Reed at breed71@gmail.com.

Perched on a marsh sapling, many wouldn’t identify this as a blackbird. The female red-winged blackbird’s plumage is quite different from her counterpart’s. BARRY REED/SPECIAL TO THE TIMES NEWS
In stark contrast, a very common male red-winged blackbird shows off its bright red and yellow epaulets interrupting its glossy black plumage.
Seen alone, many would not identify the dull female ring-necked duck seen here with the male. 
A good example of the less colorful female is the American goldfinch.
A bright yellow American goldfinch perches among the buds of a spring red bud tree. BARRY REED/SPECIAL TO THE TIMES NEWS
The female cardinal lacks the bright male’s color, allowing her to be more successful while incubating her eggs.
The mallard, the most well-known duck, is the easiest dabbling duck to identify. BARRY REED/SPECIAL TO THE TIMES NEWS
A northern flicker displays a bright red patch on its nape. It and red-bellied woodpeckers also display a “ladder back” feather pattern.
Usually arriving before the females, the male common yellowthroat (type of warbler) sings and displays from a variety of perches to prove he is the fittest.
Seen alone, most would not identify this dull-colored yellowthroat female, the object of the male’s attention.