Life History Characteristics of Insular Peromyscus maniculatus in the Bonneville Basin, Utah

Small mammal populations on four sites in the Bonneville Basin of Utah were sampled to compare reproductive and life history characteristics of one island, one peninsula and two mainland populations of deer mice (Peromyscus maniculatus). The Newfoundland Mountain range has been isolated for more than 10,000 yr, whereas Stansbury Island (normally a peninsula) had been isolated by rising lake levels for approximately 3 yr prior to initiation of this study. The Newfoundland Mountain island population had slightly smaller litters, fewer breeding adult females, a markedly shortened breeding and delayed maturity-all indications of K-selection. The peninsular Stansbury Island population was similar in nearly all life history traits to nearby mainland areas. Maternal mass was significantly (though weakly) correlated with all estimates of litter size, whereas age was not a significant factor affecting litter size.