Alaska Science Center
Time allocation by Northern Fulmars during the breeding season
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Product Type: Journal Article
Authors: Hatch, S. A.
Averaged over the whole breeding cycle (pre-laying through mid-chick stage), breeding fulmars spent about 39% of their time at the breeding site and 61% of their time at sea. Annual means of site occupancy before egg-laying were positively correlated with breeding success, suggesting that time allocation was a sensitive indicator of food availability in different years. Nonbreeding site-holders spent about half as much time at the colony as breeders; their attendance was highest early in the season when pair bonds and site ownership were established. The attendance of failed birds after egg or chick loss was positively correlated with colony-wide breeding success in six years. Males spent more time at the breeding site than females at every stage of the season. Most days were devoted to foraging in the pre-laying period (69% in males, 82% in females). An extended absence from the colony just before laying (the pre-laying exodus) averaged 12.2 d in males and 17.6 d in females. Changes in body weight indicated that neither sex incurred an energy deficit on a seasonal basis. A greater investment by the male in site attendance during incubation offset the female's investment in egg production and assured that both sexes entered the demanding chick-feeding stage in good condition.