The hypothesis that a late spring arrival and a dull nuptial plumage can aid yearling male passerines in avoiding aggression from territorial adult males was tested. Adult male black-headed grosbeaks, Pheucticus melanocephalus, were presented with three types of conspecific models: (1) adult male, (2) yearling male with bright plumage, and (3) yearling male with dull plumage. Models were associated with a song playback and were presented at (1) the time of adult male arrival and territory establishment, and (2) 2 weeks later at the time of yearling arrival and settlement. Test males were more aggressive toward all model types during early presentations than during late presentations. In addition, adult models elicited more aggression [...]
