Reindeer summer activity pattern in relation to weather and insect harassment

Authors

  • Rolf Iver M. Hagemoen,

    Corresponding author
    1. Bellona Foundation, PO Box 2141, 0505 Oslo, Norway; and
      Rolf Iver M. Hagemoen, Bellona Foundation, P.O.Box 2141, 0505 Oslo, Norway. Fax: 23234623, E-mail: river@bellona.no
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  • Eigil Reimers

    1. The Norwegian School of Veterinary Science, Department of Morphology, Genetics and Aquatic Biology, PO Box 8146 Department, 0033 Oslo, Norway & University of Oslo, Department of General Physiology, PO Box 1051, Blindern, 0316 Oslo, Norway
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Rolf Iver M. Hagemoen, Bellona Foundation, P.O.Box 2141, 0505 Oslo, Norway. Fax: 23234623, E-mail: river@bellona.no

Summary

  • 1During the brief growing season in Arctic and high mountain ecosystems, undisturbed grazing is crucial in order to maximize growth and fattening. During summer 1997 we investigated the influence of weather and insect harassment on the behaviour and group dynamics of reindeer ( Rangifer tarandus tarandus L.).
  • 2Climatic data, activity of parasitic flies, and female reindeer behaviour were recorded from two wild reindeer populations in Southern Norway. Temperature and solar irradiation were good predictors of oestrid fly activity. Throughout the warm summer, reindeer were exposed to vigorous oestrid fly harassment, which caused dramatic decrease in feeding and lying, and increase in walking, running and standing. This behavioural change may compromise the physical condition of individuals entering winter.
  • 3Mosquitoes had little influence on reindeer activity patterns. In the absence of oestrid flies, weather parameters had no influence on reindeer activity pattern. Even during the warmest days, no signs of heat stress were recorded. Accordingly, snow patches, marshes and windy mountaintops were used primarily to avoid oestrid fly harassment. Thus, most disruptions of feeding that are often reported on warm days are responses to oestrids, not thermal stress.

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