AUK 117(3), 718-730 (2000)
Variation in foraging and parental behavior of King Cormorants
A. Kato, Y. Watanuki, I. Nisiumi, M. Kuroki, P. Shaughnessy, and Y. Naito
We studied sexual and individual differences in foraging and parental behavior of King Cormorants (Phalacrocorax albiventer) rearing chicks were studied at subantarctic Macquarie Island. Females dived mainly in the morning and males in the afternoon. Five females were shallow divers (1.9 to 6.8 m) and seven were deep divers (19.6 to 28.0 m), but males dived even deeper (15.6 to 44.2 m) than both type of females. In King Cormorant, males were 16% heavier than females and the body mass was not different between deep divers and shallow divers of females. The percentage of bottom time to dive cycle was larger for shallow diving females (40 ± 13%) than males (26 ± 4%) and deep-diving females (27 ± 3%). Total daily dive time and bottom time did not differ between males, deep- and shallow-diving females, because shallow-diving females dived more frequently (211 ± 81 dives per day) than males (68 ± 21 dives per day) and deep-diving females (70 ± 7 dives per day). Meal delivery rate, trip duration and percentage of time at sea did not differ between males, deep- and shallow-diving females. Females, especially shallow divers, compensated their shallow and short dives with more frequent dives. Consequently male and female cormorants provisioned their chicks at a similar rate, in spite of large sexual and individual variation in foraging behavior.
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