Electronic Thesis and Dissertation Repository


Master of Science




Dr. J.S. Millar

2nd Supervisor

Dr. F.J. Longstaffe

Joint Supervisor


Timing of breeding in seasonal environments is important in population dynamics, but it is not always known what cues animals use to time breeding. In northern deer mice (Peromyscus maniculatus) at Kananaskis, Alberta, Canada, early seasonal births are related to overwinter protein supplementation. It is not however known if natural variation in diet quality has the same effect. I hypothesized that yearly winter arthropod availability would influence yearly spring breeding. I predicted that the mean date of initiation of breeding in the population would be related to overwinter diet quality, indicated by 15N enrichment of hair of overwintering adults. Mouse hair was collected between 2004 and 2011 and analyzed for carbon and nitrogen isotopic compositions. Initiation of breeding varied significantly among years but there was no relationship to stable isotopic composition. Thus, factors other than the availability of arthropods appear to affect the initiation of spring breeding.