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September 22, 2021

Return of Bird of the Week: Hairy Woodpecker

Male Hairy Woodpecker, Fairbanks, Alaska
The Hairy Woodpecker is one of the most widely distributed and most highly variable bird species in North America. Found from the south slopes of the Brooks Range in northern Alaska to the mountains of Panama, it’s familiar to anyone who has hung up a suet feeder. But in the woods, it’s fairly rare to see a Hairy Woodpecker. For a big bird, that drums frequently, it can be hard to find. They aren’t “hairy,” of course. The name comes from the long, thread-like feathers in the whitish areas on their backs. Those feathers are difficult to see in the field, except on a windy day. This species has evolved to drill into even hardwoods, excavating cavities for nesting and chasing insects clear into the heartwood of trees.
Female Hairy Woodpecker, Delta Junction, Alaska
While Bergmann’s Rule – the theory that endothermic animal size varies by latitude and altitude – has been criticized, it’s certainly the case that the further north you go the larger Hairy Woodpeckers are. They show a decrease in size of the culmen, tarsus, wing, and tail, roughly following a smooth cline, from north to south and from higher to lower elevations. It’s a classic example of Bergmann’s Rule.
Lousy Photo of Male Hairy Woodpecker, La Selva, Costa Rica
The last photo is included only as documentation that the species is, indeed, found in Central America. This subspecies is at least an inch shorter than Alaska’s. The motion blur is a result of the low light; it may look bright, but this is ISO4000, f5.7 and 1/80 second. Over 1-3 weeks (depending on the tree), a mated pair excavate a fairly large cavity in a tree or snag. The female lays 3-7 eggs that hatch in 11-15 days. The female broods the young for about 5 more days. After about a week, the nestlings become noisy, calling for food. Hairy Woodpecker nests are surprisingly easy to find. Nestlings fledge in about 28-30 days. Hairy Woodpeckers have a high breeding success rate (at least one hatchling fledging), about 78%. Hairy Woodpeckers live 11-15 years. WC speaks from personal experience when he reports that Hairy Woodpeckers can damage wood-sided homes in Interior Alaska. Silicon caulk discourages them for enlarging cavities they’ve started (they don’t like the taste). If you know of a way to stop them from starting new cavities, pass it along in a comment. For more bird photographs, please visit Frozen Feather Images.



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