Meeting Abstract

30.4  Monday, Jan. 4  Physiological Correlations of Neophobic behavior: Is Regulation of the Hypothalamic-Pituitary-Adrenal Axis Correlated to Responses to Novelty? LIEBL, Andrea L.*; SCHMIDT, Evelyn J.; MARTIN, Lynn B.; University of South Florida aliebl@mail.usf.edu

One of the best predictors of success for an introduced species is response to novelty. Animals can be attracted to (neophilia), fearful of (neophobia), or indifferent to novelty, but those that minimize neophobia or enhance neophilia are most likely to exploit unfamiliar resources in new areas. Novelty has previously been associated with glucocorticoids (GCs), hormones released in response to stressors. In laboratory rodents, elevated GCs typically reduce interest in novelty. In the present study, we investigated relationships between GC regulation and response to novelty in house sparrows (Passer domesticus), a notoriously successful invader. We then experimentally manipulated GCs to assess their direct influence on response to novelty. We found that GC elevation in response to restraint was strongly positively correlated to dexamethasone-induced negative feedback, indicating that individuals releasing the most GCs also reduced it most rapidly. In terms of effects on novelty, individuals that released more GCs in response to restraint were also slowest to interact with a novel object when tested later in captivity and individuals with the most rapid negative feedback approached and consumed novel food most quickly. Direct manipulation of GCs indicated that these relationships were likely indirect, as treatment with metyrapone (to block GC surges in response to stressors) and corticosterone did not affect response to novel food or objects. In sum, GC regulation and response may be a physiological indicator of neophobia, and future study of regulation and neophobia in free-living birds will rectify captivity confounds and address possible correlations with invasion.