Home range size and movement patterns of female lynx (Lynx lynx) during the yearly survey period in reindeer husbandry area

University essay from SLU/Dept. of Ecology

Abstract: To estimate the number of lynx (Lynx lynx) within the reindeer husbandry area, an annual survey takes place between 10 January – 28/29 February every year. To distinguish between family groups in the survey, a distance criteria of 25 km is used. Depending on lynx movement pattern, i.e. the distance a lynx travels during a certain period, the distance criteria may over- or underestimate the lynx population size and therefore influence the outcome of the survey. The survey overlaps with the start of the lynx mating season, thus there is a possibility that the mating season has an affect on lynx home range size and movement pattern, with risks of affecting the annual survey. Habitat may also affect the movement pattern of lynx, since it may differ in aspects such as prey abundance and thereby possibly affect home range size. The aim of this study was to identify if mating season or type of habitat may impact lynx spatial pattern, and whether the distance criteria are a reliable method to use in the survey. The data used in this study was collected from 20 female lynx fitted with GPS-collars within the reindeer husbandry area in Sweden. Home range sizes during the survey period varied greatly between individuals (105-1521 km2, average 486 km2). There was no significant difference in weekly home range size or in movement pattern within the study period. These results indicate that female lynx do not change their spatial pattern during the survey period. There was no significant correlation between habitat and lynx home range size or movement pattern. Cumulative home ranges were compared with the distance criteria. After 7 weeks, the average cumulative home range was larger than the distance criteria. When the maximum length of the cumulative home ranges was compared with the distance criteria, the distance criteria were exceeded after 4 weeks. Within a survey period of 7 weeks, 69 % of the lynx had moved over larger distances than 25 km. These results show that the distance criteria need to be reevaluated.

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