Three-toed woodpeckers

a delightful encounter

On a nice June day I was traipsing along the Outer Point trail when I heard some loud chattering. As I got closer, I saw two women standing in the trail, gazing up at the source of all the noise. There was a hole in a small dead tree, maybe ten feet up, and the chatterer’s head poked out. A woodpecker, of course, but which one? The parents were very diligent and also very quick while making their food deliveries, but after several parental visits we were sure they were American three-toed woodpeckers. Oh good, this was a chance to watch a bird that is not very common around here, although they are widespread across North America, in the northern and montane conifer forests.

None of us had binoculars that day, so I went back the next day, better equipped, so I could more clearly see the chick in the nest doorway. It was big enough to fill the entire opening, and it seemed to stay there, with its head near the door all the time I watched. So I don’t know if it had siblings down in the nest behind it. Normally, there might be three or four chicks in a nest. Although it was possible that some chicks had already fledged, if so, they were already dispersed well away from the nest site; I was confident that the parents did not have other chicks close-by. The one in the nest opening chattered incessantly—and I do mean incessantly!—even when it rested its head on the doorway and closed its eyes. Its tune changed when a parent arrived, or came into view nearby, with a load of food. Then the call notes got louder and slightly farther apart. But the regular clamor resumed as soon as the food delivery was accomplished. An insatiable offspring!

The very next day I went back again, with some special international guests, for the chance of seeing a new (for them) bird species. The huge chick was still in the nest, calling and calling, but now with a new little whirr in its repertoire. We all waited for an hour, and then I waited for another hour, but no parent birds came. Disappointing! It was very different from the previous day, when the parent birds delivered little tidbits every ten minutes or so. (The tidbits were really small, and quickly delivered. Very different from another nest I later observed, at which the large loads brought by both parents gave the chicks several ‘bites’.) Was this abandonment, or part of a weaning process, or….?

Photo by Bob Armstrong

The next day, the chick slept in the doorway, occasionally making rather soft calls. Two days later, the doorway was empty. I hope the chick fledged and is now following its parents around, begging and starting to learn how to flake off scales of bark.

Both parents usually participate in all phases of nesting: excavating a cavity, incubating (at least both have brood patches), feeding nestlings and fledglings. Males have a yellow crown patch that females lack, but—oddly—chicks of both sexes have a yellow patch, which is eventually lost by females.

The parents had been unfazed by us standing in the trail, just a few feet away from the nest tree. Nor were they bothered by a dog, a small child and her father sitting right below the nest. They obviously persevered through the noisy process of recent trail repair in that area, which must have overlapped at least with the early part of the nesting cycle, perhaps through the approximately two weeks of incubation and the first part of the three-week nestling period. Amazing resilience!

Three-toed woodpeckers forage chiefly by scaling bark on dead and dying trees, using a sideways strike of the bill, and bark beetles are said to be a major food. But they also drill for wood-boring beetle larvae (though less often and less deeply than the related black-backed woodpeckers). Surprisingly, in spring and early summer, at least in some areas, they also make sap wells in bark and sip the sap, as sapsuckers do regularly (although they may not have the brushy tongue that sapsuckers use to lap up sap; I found no information on that).

By why do they (and the black-backed) have only three toes (pointed forward), when most other woodpeckers have four toes (three forward and one back)? It might have to do with how they pound on the tree trunk. To initiate the strike, they lift the whole body away from the tree, standing more or less on tiptoe with heels raised. It is thought that a fourth toe at the back of the heel might interfere with raising the heel as part of delivering the whole-body strike. In addition, the head drives forward. Ribs near the base of the neck are broader than usual, for extra muscle attachment, aiding the strike and stabilizing the neck. So they can deliver quite a wallop.

Ah, but doesn’t such a hard strike hurt their heads? Maybe not: certain muscles related to bill movement may absorb some of the shock and help spread the shock over a wide area.


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