Chapter 12 - Testosterone, Territoriality, and Social Interactions in Neotropical Birds

Abstract

Our understanding of hormone–behavior relationships is largely based on studies of northern latitude species. Such studies have greatly expanded our general knowledge of the role of testosterone in free-living animals, particularly birds. Results from such studies have resulted in the development of the challenge hypothesis, which posits that testosterone levels rise above those necessary for reproduction due to social interactions. However, the vast majority of animals inhabit the tropics and have very different life histories as a consequence. In fact, many southern latitude species have life histories more like tropical species than like their counterparts from northern latitudes. The broad applicability of the findings based on northern species is thus questionable. Based on the few studies of neotropical birds, it appears testosterone and its role in reproduction and social interactions are very different from northern species. Testosterone levels do not elevate in response to male–male interactions, and blocking testosterone does not suppress territorial intrusions. Further studies of both tropical and southern latitude species are thus warranted to develop a broader and deeper understanding of testosterone and its role in reproduction and associated territorial aggression.