The Pas Area annual muskrat house counts / Robert G. Smith and Christopher E. Smith.

Includes bibliographical references.

Since 1979 Ducks Unlimited (Canada) has been conducting aerial muskrat house counts on selected basins throughout The Pas area. Three major complexes were surveyed and are outlined o Figure 1. The purpose of this survey is to monitor general muskrat population trends on marshes which D.U. manages. In 1979 and 1980, the survey was conducted in the early fall, just after freeze up when houses are most visible. Due to poor counting conditions experienced during the fall of 1981, this census could not be conducted. As an alternative, the census was conducted during the spring of 1982 (April 14th - 18th), however, the results represent 1981 house building activity. Ideally, counting should take place in the fall just after freeze up when there is a skiff of snow on the ground. If temperatures are mild, the snow melts off of the houses and they show up as being black against the white snow background. It was found that these conditions cannot be met in the spring in every case due to drifti