Population dynamics of a beaver population in northern latitudes

Abstract

The first thorough investigation of the status of beaver populations in Wood Buffalo National Park was reported by Soper (1937). At that time the lowlands of the Peace and Athabasca deltas were largely devoid of beaver, although the suitable beaver habitat in the upper plateaus was occupied. Soper estimated that Wood Buffalo National Park, an area of 17,300 square miles, was capable of supporting a total population of 75,000 to 100,000 beaver. This was a most optimistic estimate in view of the management practices in force at that time. Trappers, entirely dependent upon the beaver, overexploited the resource badly, until by 1945 the accessible populations had been reduced to such low levels that the trapping season was discontinued. In 1949 the Canadian Wildlife Service introduced 50 beaver from Prince Albert National Park into the Peace-Athabasca delta regions in an effort to rejuvenate the decimated populations (Law, 1949). Pairs were released in habitats that were judged suitable on the basis of available water area, water depth and food supply. Two breeding pairs were introduced into "individual trapping area" Number 1140, an area which was assigned to one trapper and later became the study area upon which part of this report is based. Six pairs were released immediately north of the study area in a "group trapping area" assigned to 53 trappers. The trapping season remained closed until 1953, when the transplant was considered successful and trapping quotas were established which are still in force.

The purpose of the present study was to investigate the life history and ecological relationships of beaver in a study area in Wood Buffalo National Park, in order to determine whether beaver at these latitudes can approach densities found in more southern areas, and whether they can be exploited on a sustained yield basis. From 1956 to 1964 the study included a census of beaver colonies within the study area, the balance of Wood Buffalo National Park, and the Mackenzie drainage of the Northwest Territories. A study of age of beaver, age composition of colonies, population growth, movements and carrying capacity of beaver habitat was also done in the study area. Data from a similar study in Prince Albert National Park were also made available through the Canadian Wildlife Service. During 1959 and 1960, captive beaver at the University of Saskatchewan were studied in order to improve field techniques and to characterize vocalization and behaviour.