Effects of investigator disturbance on corticosterone concentrations of black-legged Kittiwake chicks

Recent studies indicate that young seabird chicks exposed to relatively short periods of elevated levels of plasma corticosterone may suffer lifelong cognitive impairment that is detrimental to their survivorship and fitness as adults. We examined the chronic effects of investigator disturbance on the baseline and acute stress-induced levels of plasma corticosterone of Black-legged Kittiwake (Rissa tridactyla) chicks in Chiniak Bay, Kodiak Island, Alaska, in 2005. Kittiwake chicks were assigned to one of three disturbance treatments: (1) routine handling, (2) exposure to investigator presence, but not handled, and (3) neither handled nor exposed to investigator presence prior to sampling. At 12-15 d posthatching, blood samples were collected to determine baseline and stress-induced concentrations of corticosterone. We found no significant differences in baseline or stress-induced levels of corticosterone among the three disturbance treatments. Our results suggest that Black-legged Kittiwake chicks do not perceive investigator presence as a stressor. However, investigators studying kittiwakes at other locations should proceed with caution because sampling protocols and environmental conditions may differ, potentially causing chicks to perceive disturbances differently as well.