Do volatile repellents reduce wolverine Gulo gulo predation on sheep? Results of a large‐scale experiment
1998
Landa, Arild | Krogstad, Steinar | T⊘mmerås, Bj⊘rn Åge | Tufto, Jarle
Experiments with captive wolverines Gulo gulo showed that oils and chemicals gave distinct avoidance reactions. In 1993 and 1994, volatile repellents were tested on lambs in free‐ranging flocks and significantly fewer lambs were lost in treated groups than in untreated groups. In 1996, the effects of repellents were tested when wolverines did not have lambs without repellents as alternative prey. The experiment was carried out in four different areas where high losses of lambs due to wolverine predation had been observed in recent years. The flocks were monitored by environmental officers throughout the season. There were relatively few technical problems with the repellents, except that some ear tags were lost during the grazing season. The effect of the repellent was tested on two different time scales, a survival model based on 15 years of data and a model based on a narrow time window, comparing the results of the test year with the losses in the previous year. Losses of lambs increased from 1983 to 1996 and were highest in years in which wolverines reproduced within the areas concerned. Both models showed that the use of volatile repellents on all lambs did not reduce losses in either of the four areas. In one of the areas (Ulvådalen), the losses were higher in 1996 than in 1995. In the other three areas, no difference was found between 1995 and 1996, suggesting that the wolverines had become habituated to a situation where all the lambs in a relatively large area were treated with repellents. Based on the results of former surveys as well as the present survey, we conclude that this particular repellent is only a potential tool which may be used to reduce losses in target groups of sheep and that repellents cannot be recommended as a general tool to reduce wolverine predation on sheep.
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