Earlier arrival to reproductive sites of males relative to females (protandry) is widespread among migratory organisms. Diverse mechanisms have been proposed that may select for protandry, including competition for limiting resources (e.g., territories) or mates. In species with large variation...

To understand interspecific patterns in the strength of sexual selection, variation in the costs and benefits of exercising mate choice needs to be evaluated. One manifestation of sexual selection in birds is the occurrence of greatly variable levels of extrapair paternity (EPP). A proposed...

Neural correlates of bird song involve the volume of particular song nuclei in the brain that govern song development, production, and perception. Intra- and interspecific variation in the volume of these song nuclei are associated with overall brain size, suggesting that the integration of...