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|All Authors / Contributors:||Robert W Stewart; J Roger Bider|
|Notes:||Fig. 1. 1972 summer and fall muskrat captures, movements, and approximate breeding territory limits. When muskrats were caught more than once at the same trap station the frequency is indicated by the offset number at the capture location.
Fig. 4. Percentage of days each sandtrack was crossed by muskrats (solid portion of bars) during activity periods A and B. Approximate breeding territory (BT) limits are enclosed by dashed lines. N is the number of days in each period.
The activity, spatial distribution, and movements of a population of muskrats (Ondatra zibethicus) living in drainage ditches at Mirabel, Quebec, were related to selected weather variables. Sandtracking and mark-recapture techniques were used to collect data. On rainy days amount of rainfall, temperature drop at dusk, and an index of nocturnal light intensity explained 38.0, 5.1, and 8.1 percent of the variation in daily activity. On days without rainfall the mean daily temperature explained 11.5 percent. All variables, except for the temperature drop at dusk, were positively correlated with muskrat activity. Daily activity was higher on days with diurnal rain than on days without rain or days with nocturnal rain. Regardless of weather the diel rhythm of the muskrats was bimodal with peaks occurring in late afternoon (between 1600 and 1700) and following sunset (between 2200 and 2300). On days without rain muskrat activity was mainly restricted to the areas of the ditches surrounding burrow systems. Muskrat activity increased in all parts of breeding territories on rainy days and a significantly greater proportion of total activity was spent in the peripheral areas. On days without rain only 20 percent of all recorded muskrat movements extended over 120 m while on rainy days 42 percent of the movements were greater than this distance. There was a positive association between the distance moved and the amount of rainfall. A short term drought caused the muskrats to restrict their activity to the immediate area around their burrows.