HORMONAL CORRELATES OF BOWER DECORATION AND SEXUAL DISPLAY IN THE SATIN BOWERBIRD (PTILONORHYNCHUS-VIOLACEUS)

Male Satin Bowerbirds court females with complex displays that include stick structures built adjacent to a decorated display court. Here we report circulating levels of testosterone and corticosterone in a natural population of Satin Bowerbirds and their relation to the development of complex mating displays. We found that (1) males without bowers had lower levels of testosterone than bower holders, (2) testosterone, but not corticosterone, levels were significantly correlated with male mating success, and (3) levels of testosterone, but not corticosterone, were consistently correlated with the quality of several important display characters that have been shown to be important in affecting male mating success. These results suggest that testosterone level is an important component of male mating success. We consider reasons why variation in testosterone levels persists among mature male bowerbirds given its potential to affect male mating success.