Date of Award


Degree Type


Degree Name

Doctor of Philosophy


It has been proposed that bushy-tailed woodrats (Neotoma cinerea) exhibit a harem-polygynous social system (Escherich 1981). I monitored 16 groups of N. cinerea in rocky habitat in the Kananaskis Valley, Alberta, from 1984 through 1986 to determine whether reproduction, growth, group size, and group sex ratio of this species were proximately limited by food abundance. Supplemental food was supplied to 8 groups through 2 successive breeding seasons, and the fed and unmanipulated groups were monitored using mark-recapture techniques. N. cinerea first bred as yearlings, with females producing 1 or 2 litters each season. Food addition resulted in early breeding (p {dollar}<{dollar} 0.02), an increased number of litters per season (p {dollar}<{dollar} 0.05), and an increased litter size at weaning (p {dollar}<{dollar} 0.05). Food addition also increased post-weaning growth (p {dollar}<{dollar} 0.0001) and overwintered body weight (p {dollar}<{dollar} 0.005). These results support the hypothesis that food is a proximate limit to female reproduction and growth. The average group of N. cinerea consisted of a single overwintered male and 2 or 3 overwintered females with associated juveniles. Group sex ratio was female biased on the majority of areas (69% in 1985; 88% in 1986). Most females (71%) but few males (17%) were born on the area on which they subsequently bred. The variable components of N. cinerea social organization were male ranging behaviour and female group size. The majority of overwintered males (54%) were only trapped on a single rocky outcrop. The remaining males roamed among adjacent outcrops (17%), or were non-territorial transients (29%). These alternate ranging tactics were related to differences in age and body weight among males. Each overwintered female was closely associated with a single rock outcrop. Female group size was positively correlated (r{dollar}\sb{lcub}\rm s{rcub}{dollar} = 0.62, p {dollar}<{dollar} 0.02) with the length of these outcrops. However, neither group size nor group sex ratio were influenced by food addition. These results do not support the hypothesis that food is a proximate limit to the level of polygyny exhibited by N. cinerea.



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