In Sweden the Short-eared Owl is a summer bird that migrates and therefore largely leaves the country in winter.
Migration: it arrives in spring and leaves in autumn to overwinter in more southerly areas.
In Sweden: single birds may remain during mild winters, especially in good vole years, but the majority move away.
Population fluctuations: the availability of small rodents governs both breeding and how many birds move through the landscape, which makes its occurrence unpredictable from year to year.
Being tied to open country and small rodents means it follows the food supply and can turn up far outside its usual haunts.