Shifts in food availability and associated shifts in space use and diet in stone marten
Spacing patterns of mammals are commonly assumed to be influenced by changes in food availability, resulting in shifts in diet. However, there is a lack of detailed case studies proving this relationship. We present here such a study carried out on two stone martens (Martes foina). We collected data on individual space use by radio telemetry, measured the diet by faecal analysis, and assessed changes in food availability of some main food items. Overall, changes in space use were paralleled by changes in diet, and might have been the result of changes in local food availability. In one case the animal stopped being active in a part of its home range when the high local availability of fruit (cherries) decreased in late summer. This decrease in cherries within its diet was mostly compensated for by increased ingestion of other kinds of fruit and of small mammals. In another case, the animal temporarily ventured into an area outside of its usual range of activity during winter when the availability of its seasonal staple food, earthworms, was low. In the new area, it fed on the available fruits and small mammals.