Early maturation by northern <i>Peromyscus maniculatus</i>

Abstract

Female Peromyscus maniculatus rarely breed as young of the year in the Kananaskis Valley, southwestern Alberta. We monitored breeding by young-of-the-year females in unmanipulated sites from 1985 to 1991 and on manipulated sites (females removed, males removed, and food added) from 1989 to 1991. Breeding by young females was uncommon on all manipulated sites (16% when food was added, 3% when females were removed, 0% when males were removed). Females that matured as young of the year tended to have relatively high growth rates as nestlings. We conclude that individual quality is more important than social cues in regulating maturation by young females in this population.