Meeting Abstract

P1.13  Saturday, Jan. 4 15:30  Disentangling Territorial Behavior in a Year-Round Territorial Songbird VILLAVICENCIO, CP*; QUISPE, R; GAHR, M; GOYMANN, W; Max Planck Institute for Ornithology, Seewisen, Germany cvillavicencio@orn.mpg.de

Testosterone affects several traits of animals including physiology, morphology and behavior. Seasonal elevation of testosterone often correlates with aggressive and mating behaviors. Therefore testosterone has been related to territorial and mating behavior in a wide variety of bird species. However, this relationship is not always straightforward. For example, male black redstarts (Phoenicurus ochruros), a socially monogamous songbird, do not only show territorial behavior during the breeding season but year-round. Further, they do not increase testosterone during male-male challenges. Thus, the objective of our study was to investigate the role of testosterone and its relationship with aggressive behavior, as well as looking for aromatase expression during different stages in male black redstarts. We measured plasma levels of testosterone of males during three different stages: breeding, molting and non-breeding. We compared these hormone levels to territorial behavior during simulated territorial intrusions, including song behavior. In addition we measured the aromatase expression in the preoptic area (POA). Our results show differences in plasma testosterone levels between stages, being higher at the beginning of the breeding season, compared to molting and non-breeding. The same was found for aromatase expression in the POA. Aggressive behavior was similar between stages, but song parameters differ between breeding and non-breeding. In combination with prior work our data suggest that sex steroids play only a minor role in the regulation of territorial behavior in this species. We propose that the control of territorial behavior in species that are territorial throughout their annual life cycle can be decoupled from testosterone.