When most people think of woodpeckers, they think of a robin-sized bird clinging to a trunk and bashing away with its bill attempting to extract some beetle grub or other insect from beneath the bark of a tree.
This is the life of most woodpeckers, but every family has its black sheep, and the woodpecker family has more than one oddball. Sapsuckers pound on trees to create oozing sap wells that provide them sustenance. Sap is sweeter than grubs. Acorn woodpeckers have abandoned the grub diet to become largely vegetarian. Acorns may be bitter, but oaks provide an abundant and nutritious food source.
There is another oddball in the clan, although not quite as rebellious. It’s the northern flicker. Most have seen this brown bird flushing from a lawn and sporting a large white rump patch. A better view reveals bright salmon-colored linings of the wings and tail, hence its former name of red-shafted flicker. They also have a boldly speckled belly and a black crescent on the chest.
If you thumb through your field guide, notice the back color of woodpeckers. Almost all are black, from the large pileated woodpecker down to the diminutive downy woodpecker. One is even named “black-backed woodpecker.” Some species have splashes of white mixed in, but the theme is black.
Unless it is spring and females are about, the strategy for most birds is to go about business unnoticed. Look out at the trees in your backyard. On a sunny day, half of the trunk is in deep shade, nearly black. On a cloudy day the entire trunk is dark. Black is good if you spend most of your time in the shadows. Even if the trunk is decorated with sun flecks, most woodpeckers have this covered, too, with small spots of white on their backs.
The exception to this general pattern is the northern flicker. The back of the flicker is brown with narrow black bars. Why? Remember, I said you are likely to see one when it flushes from the ground? They have a passion for ants, and the ground teems with ant colonies.
Ants are not for everyone. The formic acid they contain is bitter and to some degree toxic. Few animals around the world have adapted to this abundant if somewhat nasty food. These include anteaters in South America, numbats in Australia, pangolins in Asia and, closer to home, horned lizards. This is a rather eclectic group.
If a bird spends most of its time on the ground harvesting ants, black might not be the most concealing of colors. Brown is a much better option for avoiding the attention of a hawk or other predator.
Other than its unique feeding habits, the flicker is a perfectly good woodpecker in its behaviors. It excavates nesting cavities in trees with its stout beak. And when it comes to courtship and declaring a territory in the spring, like any good woodpecker it finds a resonant snag (or metal chimney or gutter), usually around the crack of dawn, and pounds away for all to hear, including sleeping humans.
Now for those of you who did consult your field guide, you may have noticed that the female Williamson’s sapsucker also has a brown back. Sorry, I cannot explain why. But it is biology, and there are always exceptions.
Stewart Janes is a biology professor at Southern Oregon University. He can be reached at email@example.com.