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

Abstract

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.

Effects of repeated investigator handling of Leach's Storm-Petrel chicks on growth rates and the acute stress response

“…Despite the propensity of adult Leach's Storm‐Petrels to abandon breeding attempts in response to handling by investigators (Blackmer et al , Carey ), developing chicks appear to be robust when exposed to routine handling and measurement. Similar results have been reported for cavity‐nesting American Kestrels ( Falco sparverius ) and European Starlings ( Sturnus vulgaris ) (Butler and Dufty ), open‐cup cliff‐nesting Black‐legged Kittiwakes (Sandvik and Barrett , Brewer et al ), and burrow‐nesting Thin‐billed Prions (Quillfeldt et al ). Our results provide further assurance that researcher disturbance has no apparent effect on semi‐altricial chicks.…”

“…One possible explanation for the absence of an effect of daily handling on Leach's Storm‐Petrel chicks is that the duration of daily handling (∼3 min) was not sufficient to elicit chronic elevation in baseline and acute stress‐induced plasma corticosterone concentrations, as was found in Black‐legged Kittiwake chicks (Brewer et al ). Another possibility is that repeated handling was not perceived by the chicks as stressful over the long term.…”

“…However, because chicks are typically not exposed to predators, they may not be adapted to respond to acute predation stress at this stage of their life history. These life‐history attributes could help explain the lack of chronic stress response elevation as a result of investigator disturbance in other semi‐altricial species (Butler and Dufty , Brewer et al ). Finally, we may have detected no effect because corticosterone levels may peak before or after 30 min, a time interval when levels typically peak for passerines (Wingfield et al , Newman et al ), but possibly not for procellariiforms.…”

“…However, not all semi‐altricial species are affected by disturbance during early development. For example, investigators found no effect of human disturbance on growth or baseline and stress‐induced plasma corticosterone concentrations of Black‐legged Kittiwake ( Rissa tridactyla) chicks (Sandvik and Barrett , Brewer et al ) or Thin‐billed Prion ( Pachyptila belcheri ) chicks (Quillfeldt et al ). Importantly, in addition to conflicting effects of repeated disturbance on semi‐altricial chicks, investigators in previous studies have not examined the possibility that disturbance during early development may have persistent effects on growth or stress physiology later in development or, in contrast, that chicks recover from acute effects of repeated disturbance.…”

Effects of developmental conditions on nestling American Kestrel (Falco sparverius) corticosterone concentrations

“…For example, fledgling Magellanic Penguins (Spheniscus magellanicus) showed no difference in baseline or stress-induced CORT across tourist and non-tourist visited areas [51] and Black-legged Kittiwake chicks (Rissa tridactyla) did not differ in their baseline or stress-induced CORT across levels of investigator disturbance [7]. R epeated exposure to stressors may have severe negative consequences on developing young such as suppression of growth [29] and reduced cognition [21] and even influence the probability of survival [4].…”