Tuesday, November 27, 2012

THE ANT-EATING WOODPECKER


Most of us think of woodpeckers as black and white birds that forage on tree trunks, hitching their way up, down and around to probe into bark crevices for insect larvae. Not finding any on the surface, they are supremely adapted to chiseling their way into the wood to extract burrowing beetle larvae from their hidden galleries beneath the bark.

One woodpecker stands out against this generality. It is a typical woodpecker in anatomy but not in color or foraging habits. This is the Northern Flicker (Colaptes auratus), a common breeding species over much of North America. The brown plumage, heavily barred and spotted with black, is distinctive, and, as in many other birds that feed on the ground, serves as camouflage. Males are easily distinguished by their red malar stripe.

Flickers are the only ground-feeding woodpeckers in North America. They nest in holes that they excavate in tree trunks, but their primary diet of ants, among the most abundant insects, has them nesting at woodland edges and foraging in open country when they are not breeding. Watch for flickers flying up from the ground, their contrasty white rump and red wing linings almost startling at first sight.

Flickers are still common everywhere they occur, and in the Pacific Northwest they are becoming more common in urban and suburban habitats. Every ant-filled lawn is a feeding station for them, and they quickly learn to come to bird feeders with either suet or seeds. Watch a flicker at a seed feeder sticking its tongue into the seeds. The seeds stick to the sticky tongue just like ants in an anthill and are slurped in with gusto. Bits of suet are chipped off with the powerful bill, while squirrels wait below to get all the pieces dislodged.

Ants stay underground when temperatures drop below freezing, and flickers wintering at high latitudes change to a diet of fruits of all kinds. Poison ivy berries are among the most common, and they illustrate an interesting fact of nature: poison ivy toxins are harmful only to mammals. If mammals are deterred from eating the fruits, then much wider-ranging birds will eat them and disseminate the seeds at greater distances from the parent plant.

Although common in towns and even cities, flickers are declining slightly overall. European Starlings often outcompete them for nesting holes, but there is no definitive proof that that interaction has caused the decline. Another good possibility is the general decrease of snags, dead standing trees in which the birds can excavate nest holes. One possible reason for the surprising increase of flickers in some cities is that they can excavate in utility poles!

Dennis Paulson

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