Song Development and Territory Establishment in Nuttall's White-Crowned Sparrows

Song development and territory establishment were studied in the permanently resident Nuttall's White-crowned Sparrow (Zonotrichia leucophrys nuttalli). Hatching-year birds (juveniles) begin subsong in July, and the first crystallized songs are heard in late September. Social interaction with territorial adults accelerates song development so that song crystallizes earlier in wild juveniles than in hand-raised laboratory birds. Some juveniles begin staking out territories in September and October. At this time individuals may sing up to four song types. As time progresses settling juveniles use only one or sometimes two song types which match those of neighbors with whom they interact. Singing is performed circumannually, even during the molt in this subspecies, reflecting its year-round territoriality.