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 emphasized forces that keep young birds from becoming breeders. We develop a model of delayed breeding which includes the future acquisition of a high quality territory as a potential direct benefit of delayed breeding. Strong differences in territory quality, age-correlated asymmetries in resource holding potential, and territory site tenacity set the stage for young birds to either breed immediately on a poor territory, or obtain a high quality territory through reproductive delay on or near the site. A wide variety of species and social organizations reveal 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 frequently have restricted home ranges that encompass one or more breeding territories, and prior experience at a site improves their chances of acquiring a territory in future years. This pattern of territory acquisition argues for incorporating direct benefits into models of delayed breeding. We discuss the potential applications to understanding delayed breeding in social systems as apparently different as cooperatively-breeding birds, migratory passerines, colonial breeding gulls, and lek-breeding grouse and manakins.