A numerical "Snow Index"
for reindeer (Rangifer tarandus)
winter ecology (Mammalia: Cervidae)1

William 0. Pruitt, Jr.

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

 

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Pruitt, W.O., Jr. 1979. A numerical "Snow Index" for reindeer (Rangifer tarandus) winter ecology (Mammalia: Cervidae). Ann. Zool. Fennici 16(4): 271-280.

 

Abstract

Previous work has shown that some ecological characteristics of tundra upsik that are important to small mammals can be expressed by a mathematical model or a "Snow Index". Using results of my own and other investigators' earlier work, plus results of some 460 snow profiles taken in winter 1976-77 in the vicinity of Värriö Subarctic Research Station in Northeastern Finland, in relation to the semi-domesticated reindeer of Salla north association, I have derived a mathematical model which relates reindeer activity to features of the snow cover. The Värriö snow index (VSI) incorporates the hardness of the upper half of the snow cover, the hardness and thickness of the basal layer, the hardness and thickness of the hardest layer in the snow cover and the total thickness of the snow cover. The VSI agrees well with the winter feeding activities of reindeer near the research station and also corrrelates with the puzzling late-winter movement of the reindeer through the altitudinal tree line into the alpine zone of Värriötunturi. A field check of the VSI in the central part of northern Finland, in the northern part of Kyrö association, where herding is practiced, revealed further agreement, and indicated additional, classifiable snow-reindeer relationships.

1Report no. 72 from the Värriö Subarctic Research Station at the University of Helsinki.

 


 

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