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 spe cies 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-pre datory animal (domestic rabbit) in a total of 48 one-day terrarium tri als. In response to odours of each mammalian predator, dispensed in on e of the 3 pens, the number of voles utilizing that pen decreased sign ificantly (50-90% of initial numbers). Tawny owl and rabbit scents did not change voles' distribution in the terrarium. Bank voles climbed t wigs ('arboreal' escape) in trials with mustelid (but not canid) preda tors. Odours of stoat, weasel and marten made the voles stay out of tu bes simulating underground tunnels. Voles became significantly less mo bile in response to fox and weasel odour. The numbers of qualitatively different antipredatory behaviours of voles against mammalian predato rs (from 1 in raccoon dog trials to 4 in weasel trials) correlated pos itively with the degree of specialisation of these predators in huntin g for bank voles in natural habitats (Bialowieza National Park, easter n 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 r elying 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 Bialowi eza forest.