Conservation implications of change in antipredator behavior in fragmented habitat: Boreal rodent, the bank vole, as an experimental model

Habitat fragmentation is known to cause population declines but the mechanisms leading to the decline are not fully understood. Fragmentation is likely to lead to changes in predation risk, which may cause behavioral responses with possible population level consequences. It has recently been shown that the awareness of predator presence, resulting in a fear response, strongly affects behavior and physiology of the prey individuals. Costs arising from fear may be as important for the prey population size as the direct killing of prey. We tested how predation risk in the form of scent of a specialist predator, the least weasel (Mustela nivalis nivalis), affects bank vole (Myodes glareolus) behavior in fragmented enclosures consisting of either non-fragmented (one patch) or fragmented (four patches) habitats of the same total area. Vole movement areas tended to be larger in the non-fragmented habitat. Fear decreased vole activity and tended to increase the use of the open matrix area. No interactions between fragmentation and fear treatments or differences in breeding related behaviors or fitness were found in our short-term experiment. However, behavioral mechanisms such as decreased activity and change of movements to the risky matrix could cause negative effects and population decline in the long run. Fragmentation is a serious issue in all human exploited habitats causing animals to face more risks compared to more uniform and sheltering environments. This should be especially taken into account in conservation of habitat and the reintroduction of captive reared animals where both intact sheltering habitats and food providing have habitats become rarer.