title: [Breeding biology of the whiskered auklet (Aethia pygmaea): incubation, chick growth, and feather ontogenesis].
abstract: This is the second publication on the results of studies of the whiskered auklet breeding biology on Buldir Island. In 1993, according to the time of chick hatching the egg-laying period began in late April-early May. The single egg was incubated by both parents, which relieved each other once a day, usually at early night. Among the chicks under observation, the first hatched on June 11; the median of hatching was on June 17. After hatching, the egg shell usually remained in the nest. The chick was continuously brooded by one of parents for the first several days but since the age of 7-9 days, it stayed in the nest by itself during the daytime. Each parent fed the chick once a day, at early night, although occasional feedings were recorded also during daytime and at dawn. A newly hatched chick was covered by typical embryonal (natal) down. The remiges, rectrices, their coverts, and large feathers on pteryla humeralis had a mesoptile stage during their growth (the second down generation). The juvenile plumage consisted of semiplumes of types I and II and contour feathers of type I and, possibly, type II. In fledglings, the ornamental feathers were underdeveloped: the crest was absent and facial plumes only began growing. By reaching 100 g, the chicks left their nests at the age of about 37 days. A longer nesting period than in other Aethia auklets appears to be related to a low feeding rate due to the nocturnal activity in the colony.
authors.affiliation: Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia.
authors.forename: N B
authors.initials: NB
authors.lastname: Koniukhov
authors.forename: V A
authors.initials: VA
authors.lastname: Zubakin
authors.forename: J
authors.initials: J
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Fischer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001717:Birds / Q000254:growth & development / Q000502:physiology*; D001947:Breeding; D005241:Feathers / Q000254:growth & development*