RESPONSES OF BANK VOLES TO ODORS OF 7 SPECIES OF PREDATORS - EXPERIMENTAL-DATA AND THEIR RELEVANCE TO NATURAL PREDATOR-VOLE RELATIONSHIPS

Bank voles Clethrionomys glareolus were exposed to odours of seven species of predators (weasel Mustela nivalis, stoat M. erminea, polecat M. putorius, stone marten Martes foina, red fox Vulpes vulpes, raccoon dog Nyctereutes procyonoides, and tawny owl Strix aluco) and a non-predatory animal (domestic rabbit) in a total of 48 one-day terrarium trials. In response to odours of each mammalian predator, dispensed in one of the 3 pens, the number of voles utilizing that pen decreased significantly (50-90% of initial numbers). Tawny owl and rabbit scents did not change voles' distribution in the terrarium. Bank voles climbed twigs ('arboreal' escape) in trials with mustelid (but not canid) predators. Odours of stoat, weasel and marten made the voles stay out of tubes simulating underground tunnels. Voles became significantly less mobile in response to fox and weasel odour. The numbers of qualitatively different antipredatory behaviours of voles against mammalian predators (from 1 in raccoon dog trials to 4 in weasel trials) correlated positively with the degree of specialisation of these predators in hunting for bank voles in natural habitats (Bialowieza National Park, eastern Poland). No response of voles to tawny owl suggests that the lack of direct recognition of risk of owl predation by bank voles and their relying only on indirect cues (i.e. cover, light intensity) might be an important mechanism facilitating the owl's high contribution (60%) to the total predation on bank voles in autumn-winter seasons in Bialowieza forest.