The largest item with both species is wood-boring coleopterous larvae. These amount to 64.25 percent with arcticus and 60.66 with americanus. Caterpillars, which in this case are mostly wood-boring species, amount to 12.88 and 14.45 percent for the two birds respectively. The total of wood-boring larvae, including both caterpillars and beetles, is, 77.13 percent for arcticus and 75.11 percent for americanus, or more than three-fourths of the food of both species. * * *
Fruit skins were found in only one stomach of americanus and mast in but one stomach of arcticus. Cambium was found in 10 stomachs of arcticus and 8 of americanus. This indicates that these birds do some pecking at the bark of living trees for other purposes than getting insects, but no complaints have yet been made, from which we infer that little or no damage is done; in fact the amount contained in the stomachs is not large a little less than 10 percent.
E. H. Forbush (1927) says that “Miss Caroline E. Hamilton of Greenfield, Massachusetts, observed in late September an individual that remained in a yard from daylight till dark, making the rounds of the trees and remaining longest on the fruit trees at the tiny holes attributed to Sapsuckers. She said that the bird seemed to find good food in these pits, and it may have been eating some of the cambium.” He writes further:
Mr. E. O. Grant, a faithful correspondent of Patten, Maine, travels over considerable region and north into Quebec, spending much time in the woods. On March 6, 1922, he wrote that the spruce budworm had killed about thirty percent of the spruce in that region and nearly all the fir, and that among the dead trees he saw hundreds of both the three-toed species, together with nearly equal numbers of Downy Woodpeckers and Hairy Woodpeckers. Food for the birds was very plentiful, as dark-beetles and spruce-borers were numerous. When an invasion of caterpillars strips coniferous trees and thus exposes their trunks and branches to the hot summer sun, dark-beetles attack and virtually girdle them with numerous tunnels beneath the bark; borers get in and sometimes most of the trees die. The woodpeckers, concentrating on these dead trees from all the forest around about, help to keep down the undue increase of bark-beetles and borers which, if they became too numerous, might attack some live trees.
Behavior.—Lucien M. Turner says in his unpublished notes: “The manner of flight of this species is less vigorous than in Picoides arcticus, yet differing in a manner that is difficult to describe; the unfolding of the wings when preparing to make the upward swoop is quicker, the stroke of the wing not so strong, and the plunge not so deep.”
Both species of three-toed woodpeckers are fearless birds, tame, and unsuspicious, probably because of their unfamiliarity with man and his hostile intentions; both are less active than most other woodpeckers, this species being particularly quiet in its movements and sedentary in its habits. Mr. Brewster (1898) writes:
My previous impression that Picoides americanus is a very much less active and restless bird than P. arcticus, was fully confirmed by the behavior of this male who was almost if not quite as slow and lethargic of movement as a sapsucker. He would spend minutes at a time clinging to one spot and when he moved up the tree trunks it was in a singularly slow, deliberate manner. Only when at or near the nest did he show real animation. * * *
I have rarely seen a nesting bird so alert and keen of hearing as was this Picoides. The sound of our voices or the slightest noise made by an oar or paddle would bring him at once to the entrance of the hole, even when we were forty or fifty yards away, and every few minutes when we were sitting perfectly still he would look out turning his head in every direction. He would not leave the hole, however, until we were within a few yards of the foot of the tree and after he had drummed awhile he would return to the stub while we were sitting near its base with the camera directed towards it. * * *
On returning to the stub the bird would usually strike against it about two feet below the hole and reaching it by two or three quick, upward hops would cling to its lower edge, alternately looking in and down at us. * * * He did not once enter the nest while we were near the tree, nor did he again attempt to mislead us by pecking at the bark, evidently realizing that this ruse had failed. When he flew back into the woods he always took one of two courses and along each he invariably alighted not only on the same trees but on the same spot on each tree. He had one particular place on the trunk of a large spruce where he would spend ten or fifteen minutes at a time pluming himself and watching us, before returning to the nest.
Major Bendire (1895) quotes the following from Dr. C. Hart Merriam: