Seasonal differences in habitat selection by muskrats (Ondatra zibethicus) in a high subarctic environment: Mackenzie Delta, Northwest Territories, Canada
Differences in summer and winter habitat selection by muskrats (Ondatra zibethicus spatulata) in the Mackenzie Delta, a heterogeneous high subarctic-low arctic environment, were studied. Quantitative data consisting of 11 biotic and abiotic habitat variables were obtained from 72 winter burrow sites and 119 summer burrow sites. On the basis of burrow site locations, multivariate analysis of variance revealed that habitats used by muskrats in the two seasons differed significantly. The single discriminant function generated by a discriminant function analysis was strongly correlated with variables describing food, cover, and overwinter survival of muskrats. Muskrats in summer preferred to burrow in closer proximity to shallow water, on gentler slopes, with cover and nearer to Equisetum fluviatile than muskrats in winter. I suggest that the alteration of habitat selection behavior in relation to changes in the seasonal quality of the habitat is a condition whereby habitat breadth narrows in winter. The discriminant function correctly classified 70% of the samples. Food habits corresponded closely with intense utilization of Equisetum fluviatile and Carex aqua tilus in summer and roots of submerged aquatic macrophytes in winter. Lake ice severely limited foraging space and in some instances probably resulted in high mortality. The energy demands of reproduction, maintenance, and climatic stress were believed to be responsible for body fat reserves being very low in summer, with substantial storage taking place in winter. Lake habitats were divided into two groups on the basis of their hydrological regimes: (1) stable water level lakes (unconnected lakes); and (2) flowing water lake types (lakes connected to distributary channels). Population densities differed seasonally in these two lake types. Discriminant analysis revealed significant differences in the physical morphometry of the two lake types resulting in structurally different muskrat habitat. Submerged aquatic plant production was generally greater in unconnected lakes. These results may be of considerable aid in assessing the impact of habitat alteration particularly in the event of hydro-electric development within the Mackenzie Basin.
Bibliography: p. 140-158.
Jelinski, D. E. (1984). Seasonal differences in habitat selection by muskrats (Ondatra zibethicus) in a high subarctic environment: Mackenzie Delta, Northwest Territories, Canada (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/21051