Birds of Indian Subcontinent

The Function of Delayed Plumage Maturation in Male Black-Headed Grosbeaks

Publication Type:Journal Article
Year of Publication:1988
Authors:Hill, GE
Journal:The Auk
Date Published:1988
ISBN Number:00048038
Keywords:Cardinalidae, Eophona, Eophona migratoria, Fringillidae, Mexico, Pheucticus, Pheucticus melanocephalus
Abstract:I used data from two breeding populations of Black-headed Grosbeaks (Pheucticus melanocephalus) in central New Mexico to test alternative hypotheses regarding the function of delayed plumage maturation in male passerines. Yearling male grosbeaks displayed a wide range of subadult plumage types, but most individuals were intermediate in appearance between adult males and females. Subadult male grosbeaks arrived on the study sites about 2 weeks after adult males, with no tendency for individuals with brighter or duller plumage to arrive first. Only a few of the most brightly plumaged subadult males defended territories and attracted females; most were nonterritorial floaters. All territories of subadult males were positioned outside clusters of adult male territories with few total neighbors. When I removed adult males from their territories, the territories remained empty. These results are not consistent with predictions of the female-mimicry hypothesis, but they are in accord with those of the cryptic hypothesis.
Short Title:The Auk
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith