I stepped out for a walk this afternoon and had only gone a short way down the path when I heard the telltale tapping of a woodpecker. After a moment I spotted it, a Hairy Woodpecker, high in a leafless paper birch. It seemed to be working at a decent-sized hole, not foraging around at random, but I might not have thought anything of it a moment later I hadn’t spotted a Downy Woodpecker hard at work on a cavity already big enough for the whole front half of its body to fit into – it would peck away for a minute, then stick its head and shoulders (do birds have shoulders?) into the cavity and clear out the wood chips that had gathered inside. It was an interesting behavior to watch.
Then I found this.
The work of a Pileated Woodpecker, and obviously quite recent – check out the wood chips at the base of the trunk! Why are all the woodpeckers suddenly excavating cavities at the beginning of November? Shouldn’t they be doing that in late winter/early spring when it’s time to think about nesting? What is happening?!
The Sibley Guide to Bird Life and Behavior seems to have given me my answer. Apparently in addition to nesting cavities, woodpeckers will excavate cavities to roost in during the winter. Basically they all suddenly went, “Oh crap, it’s November already, I better get cracking if I want to have somewhere snug to roost by the time it gets really cold.”
According to Sibley, it can take about two weeks to finish a cavity – I’ll have to return to that Pileated Woodpecker tree later and see if there’s any new progress.
UPDATE. From Bernd Heinrich’s fantastic book Winter World: “In late November and early December [my birds are earlier – Heinrich is in New England, perhaps they’re on a different schedule] when temperatures are dropping rapidly and the first snowstorms blanket the woods, I often hear steady tapping unlike a woodpecker’s more intermittent rapping for food excavation. Following the sounds to a decaying tree or thick tree limb, I find the ground and/or snow below littered with small light-colored wood chips. The head of a downy or hairy woodpecker invariably appears at a round hole, then shakes to release a billful of shavings, and quickly tucks back in to resume hammering. At first I thought these birds were confused, perhaps misreading the photoperiod – the hours of daylight versus dark that many animals use to keep track of the seasons – to begin nesting a half year early. However, the finished holes excavated in late fall or winter (in more decayed wood than nest holes) were invariably used by the birds that made them for overnighting sites; I flushed out the bird in the evening by tapping on the tree, but it quickly reentered the hole to spend the night there.”