An investigation of some problems of ecology of the beaver Castor canadensis canadensis Kuhl in northern Manitoba
Nash, John Blake
During the last decade there has been a five fold increase in the numbers of beaver in the province of Manitoba. The ecological status of the beaver, the factors which brought about this population increase and the attendant game management problems form the subjects of the investigations reported in this thesis. Ecologically the beaver is a native of the aspen park and mixed wood areas of the province. Driven from this natural habitat by unregulated trapping and by the habitat reduction attendant upon the advances of agriculture, the species now exists, except for a few scattered colonies, in the northern coniferous forest which occupies most of the territory between the 54th and 57th parallels of latitude and which also extends southward on the east side of Lake Winnipeg to the Lake of the Woods. In this unfavorable district the beaver existed in small numbers until 1942 when, under the combined effects of habitat modification and a particularly well chosen plan of controlled trapping, the population began to increase sharply and within seven years rose to a number more than five times that shown by the 1942 census. The population now appears to be relatively stable under the influence of systematic trapping and it is the hope of the authorities concerned to maintain this level in the areas now in production and to increase the total by introducing the beaver to areas not presently occupied. The subsequent pages deal with the problems involved in achieving this aim...