DEMPSEY, T.D.*; SHULTZ, M.T.; KITAYSKY, A.S.; Univ. of Alaska, Fairbanks; Univ. of Alaska, Fairbanks; Univ. of Alaska, Fairbanks: Daily activity patterns and diel cycles of melatonin and corticosterone in breeding Red-legged Kittiwakes

Melatonin and corticosterone are integral to the regulation of daily activity cycles in birds. However, little is known about the relationships between diel secretion of these hormones and behavior in nocturnal foragers. In this study, we examined these relationships in Red-legged kittiwakes (Rissa brevirostris) breeding on the Pribilof Islands of the south-eastern Bering Sea. It has been suggested that Red-legged kittiwakes might be nocturnal foragers, though this has not been well documented. We conducted continuous observations of kittiwake nests during chick-rearing. We recorded parental nest attendance, foraging trip duration and chick begging and provisioning rates. We collected blood samples from parents during three time periods: (1) during daytime attendance of the nest; (2) prior to leaving the colony for the nighttime foraging trip; and (3) upon return to the colony following this trip. We found that parents forage during the nighttime and deliver collected food to the begging young in several small meals during the day. Chicks beg with the highest intensity shortly after dusk and prior to the departure of the parent. On-going analyses of hormone concentrations will show if a “dampened” diel melatonin pattern is characteristic for kittiwakes as it is for other nocturnal foragers, and if a relationship exists between the temporal dynamics of melatonin and corticosterone secretions.