Seasonal Movements, Habitat Utilization and
Population Ecology of
Woodland caribou (Rangifer tarandus caribou Gmelin)
in the Wallace-Aikens Lake region
of southeastern Manitoba

W.R. Darby

Department of Zoology,
The University of Manitoba,
Winnipeg, Manitoba, Canada
R3T 2N2

 

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Darby, W.R. 1979. Seasonal Movements, Habitat Utilization and Population Ecology of Woodland caribou (Rangifer tarandus caribou Gmelin) in the Wallace-Aikens Lake region of southeastern Manitoba. M.Sc. Thesis, University of Manitoba. 187 pp.

 

Abstract

The ecology of 30 to 40 woodland caribou was studied in the Wallace-Aikens lakes region of southeastern Manitoba, from March 1975 to April 1977. Caribou activity was monitored by aerial and ground survey during months of snowcover and by ground investigations during snow-free periods. Seasonal ranges were largely overlapping, and the same central range was used during all seasons. Mean range size varied in different seasons as follows: spring 177.5 km2, summer 130 km2 (minimum), autumn 115km2, and winter 117.5 km2. Logistic problems associated with the dense coniferous forest hampered the delineation of range size in summer. Hence, it is estimated that the summer range could have been as large as 530 km2.

In general, the amount of range occupied varied inversely with amount of gregarious behaviour. Mean band size was 3.8 in spring, 1.1 in summer, 6.2 in autumn, and 5.5 in winter. Caribou became restless in late March, dispersed in April and early May, and were essentially solitary in summer. By October, caribou were reaggregated.

Habitat utilization and movements of caribou appeared to be governed by food preference and availability, nival conditions, predators, and insects. The winter range coincided with an area of mature jackpine-spruce forest and open bogs sandwiched between two large stands of immature jackpine and mixed wood. In summer when a wide variety of food items was available, some caribou moved into surrounding habitats. In general, little use was made of less common spruce-fir-birch and black spruce-feathermoss associations.

The December calf crop was 12.5% in 1975 and 20% in 1976. Food supply did not appear to be a limiting factor to growth of the herd during two mild winters. Two incidents of wolf predation on caribou were confirmed; more probably occurred but were not detected.

At least 76.5% of cows in the study herd were antlerless, whereas most cows in surrounding herds were reported to be antlered. This suggests limited gene flow between the study herd and other herds adjacent to it.

 


 

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