110 BULLETIN 17 4, UNITED STATES NATIONAL MUSEUM 



poplar forest. The nest hole was eighty feet from the ground. It 

 was two and one-half inches in diameter and one foot deep, drilled 

 tlirough an outer sheath of sound, hard wood, and downward through 

 soft, rotten 'punk.' " 



Eggs. — The number of eggs laid by the Arctic three-toed wood- 

 pecker varies from two to six, four being the commonest number. 

 These vary from ovate to elliptical-ovate, the former shape prevail- 

 ing. The shell is dull or only slightly glossy and is pure white. The 

 measurements of 39 eggs average 21.32 by 18.94 millimeters ; the eggs 

 showing the four extremes measure 25.9 by 18.7, 25.1 by 20.2, and 

 22.35 by 17.53 millimeters. 



Young. — The period of incubation is about 14 days; both sexes 

 assist in this and in the care of the young. Only one brood is raised 

 in a season, but if the eggs are taken, a second set will be laid, often 

 in the same nest. 



Mr. Achilles (1906) watched a nest containing young for 24 con- 

 secutive hours, he and a companion taking turns at the vigil and 

 sleeping alternately within ten yards of the tree ; he writes : 



The parents, when feeding their young, usually alighted within a space of 

 three feet below the hole, and never directly at its entrance. They would pause 

 here for a moment as though fearing they were observed by someone. Then 

 they would hop up to the hole and look in, anywhere from two up to six times, 

 as if accustoming their eyes to the darkness. Once in a while grubs could be 

 seen in their bills, but, from the actions of the birds when feeding their young, 

 they appeared to be regurgitating. During twenty-four hours the female fed 

 the young thirty times, and the male twenty-nine times. 



As it grew dusk, the young gradually grew quieter, and their little "'peep- 

 peep-peep" greatly resembled those of chicks when crawling beneath their 

 mother's wings. From two o'clock in the afternoon till seven o'clock that 

 evening, two minutes was the longest period during which the young did not 

 utter a single "peep." From seven P. M. until two minutes after four the 

 next morning, the young birds ceased this continuous chattering. The mother 

 was the last to feed them at night, the time being seventeen minutes after 

 seven ; but the male was up first in the morning. At four-fifteen in the morn- 

 ing, the young uttered a few sleepy "peeps," and the male alighted three feet 

 below the hole at four-sixteen. The young birds heard him alight and imme- 

 diately commenced to chatter. The male hopped up to the hole, looked in 

 twice, and then fed them. The young birds' bills were seen, indicating that 

 they were very hungry, and were hanging on to the inner wall of the nest 

 near the entrance. Soon after this their hunger was appeased, their bills were 

 seen no more, and the parents had to go almost into the hole to feed them. 



Plumages. — The nestlings are naked and blind at first, but the 

 Juvenal plumage is acquired before the young leave the nest. In the 

 Juvenal plumage, the young male is similar to the adult male, but the 

 yellow crown patch is smaller and not so sharply defined ; the upper 

 parts are duller, browner black, lacking the glossy, bluish edgings; 

 the breast is tinged with dull buffy white; and the flanks are more 

 heavily and less distinctly barred or spotted with dull black. The 



