Young.—As in the case of most nestling birds reared in a hole in a tree, little is known of the young sapsuckers while they are in the nest.
Frank Bolles (1892) speaks of “a nest filled with noisy fledglings whose squealing sounded afar in the otherwise silent woods. * * * The parent birds came frequently to the tree, and their arrival was always greeted by more vigorous crying from the young.”
William Brewster (1876a), in his study of the bird at Umbagog Lake, Maine, says: “The young leave the nest in July, and for a long time the brood remains together, being still fed by the parents. They are very playful, sporting about the tree-trunks and chasing one another continually.”
Frank Bolles (1892) has given a very interesting, detailed account of rearing three nestlings, about to be fledged, over a period of three and a half months. The three birds were dissimilar enough in coloring to be distinguished from one another; they proved to be two males and one female; and they soon developed marked differences in conduct and personality. Mr. Bolles at first kept them in a large cage in which they had ample space to climb about and later allowed them to fly around a room. They became very tame, letting him handle them freely. They subsisted almost entirely on maple syrup and water in equal parts, fed by hand at first, but in a few days they drank readily from a basin. They caught a few flies and ate some other insects that entered the cage, attracted by the syrup. Mr. Bolles says, however, that “the number of insects caught by them in this way was small, and I do not think amounted at any time to ten percent of their food.”
The birds were lively and apparently in perfect health from the time they were captured, July 7, until October 11, when one of them, the female, began to droop. Two days later she had a convulsion in the morning and died in the afternoon. Autopsy showed that her body was well nourished and that the organs were apparently normal except the liver, which was “very large, deeply bile-stained, and very soft.”
A week later the other two birds died after exhibiting the same symptoms as the first bird. The Department of Agriculture examined the body of one of these birds and reported enlargement and fatty degeneration of the liver.
Mr. Bolles remarks that “the most probable cause of this enlargement of the liver, which seems to have been the reason for the death of the three sapsuckers, was an undue proportion of sugar in their diet. In a wild state they would have eaten insects every day and kept their stomachs well filled with the chitinous parts of acid insects. Under restraint they secured fewer and fewer insects, until during the last few weeks of their lives, they had practically no solid food of any kind.”
Summarizing his observations, he says:
From these experiments I draw the following conclusions: (1), that the yellow-bellied woodpecker may be successfully kept in captivity for a period corresponding to that during which as a resident bird he taps trees for their sap, sustained during this time upon a diet of which from 90 to 100 per cent is diluted maple syrup; (2), that this fact affords evidence of an extremely strong character, in confirmation and support of the theory that when the yellow-bellied woodpecker taps trees for their sap he uses the sap as his principal article of food, and not primarily as a bait to attract insects.
Winton Weydemeyer (1926) in Montana “observed a pair of red-naped sapsuckers * * * gathering sap to feed their young in the nest. A regular tree-route, followed alternately by the male and female, included a quaking aspen, a larger alder, and a large willow, in which borings had been made. The birds flew directly from the nest to the aspen, and gathered the sap that had accumulated since the last visit; then flew to the alder and to the willow, repeating the process; and finally flew back to the nest, without hunting for insects. Occasionally the male would vary the process by catching a few flies from the air, eating some and carrying some to the nest.”