Meeting Abstract

125.5  Tuesday, Jan. 7 15:00  Testosterone at the Top of the World: Disparate hormone-behavior interrelationships between two high-arctic breeding populations of Lapland Longspurs (Calcarius lapponicus) ASHLEY, N.T.*; WINGFIELD, J.C.; Western Kentucky University; University of California, Davis noah.ashley@wku.edu

Interrelationships between testosterone and aggression are dynamic and change in relation to life cycles even in polar environments where the breeding season is extremely truncated. At the Toolik Lake Field Station in Alaska (68°N), male Lapland Longspurs (Calcarius lapponicus) show a brief peak in plasma testosterone early in the season that coincides with aerial displays and song, but not aggressive behavior towards simulated territorial intrusion (STI). Males then mate-guard females for approx. 10 days, respond to STI, but exhibit lower testosterone levels. In addition, previous studies have shown that testosterone implants increase song but not aggression. These data suggest a temporal disassociation between testosterone and aggression. We report studies from a population of Lapland Longspurs breeding at higher latitudes (71°N; Barrow, AK) where males display extended aggressive behavior to STI over a period of three weeks, and increase testosterone levels in response to STI. These differences in hormone-behavior relationships between Toolik and Barrow longspurs could reflect habitat differences (coastal vs. inland), and duration of the breeding season that could alter synchrony of breeding and/or territory density.