Dataset for: Snow limits polecat (Mustela putorius) distribution in Sweden

Many species show range expansions or contractions due to
climate-change-induced changes in habitat suitability. In cold climates,
many species that are limited by snow are showing range expansions due to
reduced winter severity. The European polecat (Mustela putorius) occurs
over large parts of Europe with its northern range limit in southern
Fennoscandia. However, it is to date unknown what factors limit polecat
distribution. We thus investigated whether climate or land-use variables
are more important in determining the habitat suitability for polecats in
Sweden. We hypothesized that 1) climatic factors, especially the yearly
number of snow days, drive habitat suitability for polecats, and that, 2)
as the number of snow days is predicted to decline in the near future,
habitat suitability in northern Sweden will increase. We used a
combination of sightings data and a selection of national maps of
environmental factors to test these hypotheses using MaxEnt models. We
also used maps of future climate predictions (2021–2050 and 2063–2098) to
predict future habitat suitability. The number of snow days was the most
important factor, negatively determining habitat suitability for polecats,
as expected. Consequently, the predictions showed an increase in suitable
habitat both in the current distribution range and in northern Sweden,
especially along the coast of the Baltic Sea. Our results suggest that the
polecat distribution is limited by snow and that reduced snow cover will
likely result in a northward range expansion. However, the exact
mechanisms for how snow limits polecats are still poorly understood.
Consequently, we expect the Scandinavian polecat population to increase in
numbers, in contrast to many populations elsewhere in Europe, where
numbers are declining. Due to polecat predation, the expansion of the
species might have cascading effects on other wildlife populations.