DELAYED BREEDING IN AVIAN SOCIAL-SYSTEMS - THE ROLE OF TERRITORY QUALITY AND FLOATER TACTICS

In many avian societies, young birds delay breeding beyond the age of sexual maturity. Most previous hypotheses of delayed breeding have emp hasized forces that keep young birds from becoming breeders. We develo p a model of delayed breeding which includes the future acquisition of a high quality territory as a potential direct benefit of delayed bre eding. Strong differences in territory quality, age-correlated asymmet ries in resource holding potential, and territory site tenacity set th e stage for young birds to either breed immediately on a poor territor y, or obtain a high quality territory through reproductive delay on or near the site. A wide variety of species and social organizations rev eal common patterns of breeding status acquisition through behaviours as nonbreeders with site tenacity on or immediately near the breeding site. A review of 'floater' strategies reveals that nonbreeders freque ntly have restricted home ranges that encompass one or more breeding t erritories, and prior experience at a site improves their chances of a cquiring a territory in future years. This pattern of territory acquis ition argues for incorporating direct benefits into models of delayed breeding. We discuss the potential applications to understanding delay ed breeding in social systems as apparently different as cooperatively -breeding birds, migratory passerines, colonial breeding gulls, and le k-breeding grouse and manakins.