Epsilon Archive for Student Projects

Abstract

Selecting a suitable calving site is important for ungulates, especially when predators are present. Brown bears (Ursus arctos) predate on moose calves (Alces alces) and therefore influence the reproductive success of the moose. Female moose learn to reduce the chances of predation on their calves, but it remains unclear which strategies female moose apply. Therefore, the aim was to study the effect of bear predation on the choice of calving site features and site fidelity of female moose. To study the effect of bear density on calving site choice, I compared calving site features (e.g. habitat structure like distance to the nearest road, vegetation cover and terrain ruggedness) with characteristics of random sites within seven areas with different bear densities in Sweden. To study the effect of bear density on site fidelity, I compared distances between successive calving sites between areas with varying bear densities and between females that lost their calves in the previous year compared to females with surviving calves. The effects were studied using movement data of female moose, survival data of their calves and maps of the site characteristics. Female moose in areas with bears selected for higher shrub cover, higher tree cover and slightly lower distance to the nearest road compared to females in the predator-free area. Shrub cover and tree cover both increase the chance of hiding the calf from predators. The selection for higher distance to roads was strongest in the predator-free area, which indicates that the presence of bears resulted in a selection closer to roads. The distance between calving sites during subsequent years was greater in areas with higher bear density compared to the area without bears, regardless of whether the female has experienced a calf loss or not in the previous year. There was no evidence that female experience with calf predation in the previous year had an influence on the selection in most weeks or on the distance between successive calving sites, which could be caused by the relatively low sample size. In conclusion, female moose are influenced in their site selection and site fidelity by bear presence but the effect of female experience with calf predation should be studied further.