Date of Award
Doctor of Philosophy
Bushy-tailed woodrats (Neotoma cinerea) are nocturnal rodents that are usually confined to discrete rock outcrops. Several females may bred on one outcrop, and are expected to compete for limited resources. I monitored individual reproductive output of female woodrats on 22 outcrops in the Kananaskis Valley in Alberta during the breeding seasons from 1987 to 1989 to investigate the influence of competition among females on reproductive success.;My aims were two-fold. First, I tested the hypothesis that competition among females on outcrops reduces reproductive success in yearling females. I reduced densities of breeding females by approximately 50% on 11 outcrops at the initiation of the three breeding seasons, and compared reproductive success of yearlings breeding on experimental and unmanipulated (N = 11) outcrops. Relative to yearlings on control outcrops, those on removal outcrops raised more offspring to weaning, their female offspring exhibited faster post-weaning growth, and they and their daughters tended to exhibit higher annual survival. Among females that were known to have bred in one year only, those on removal outcrops produced more offspring to weaning and more daughters to breeding (in their lifetime) than did those on control outcrops. I conclude that yearling bushy-tailed woodrats experience significant socially-mediated fitness costs.;My second goal was to investigate the influence of mother-offspring relationships on space use, behaviour, and reproductive success. Adult mothers and yearling daughters that bred simultaneously on their natal outcrops were closely associated in space throughout the breeding season. Behavioural interactions between mothers and daughters were amicable, while those between adult females and non-kin were strongly agonistic. This behavioural asymmetry was maintained when all females were reproductively active. Matrilineal females (those that shared an outcrop with their mother) experienced enhanced survival over their first winter, and raised more offspring to weaning than did non-matrilineal females. I suggest that adult mothers provide their daughters with access to critical resources (e.g., den sites), and provide a protective environment against aggressive conspecifics.;Woodrat sociality appears to be characterized by (1) competitive interactions among non-kin, and (2) cohesive, beneficial relationships among mothers and daughters.
Moses, Richard A., "Intrasexual Competition And Reproductive Success In Female Bushy-tailed Woodrats" (1992). Digitized Theses. 2154.