Effects of fragmented breeding habitat and resource distribution on behavior and survival of the bank vole (Myodes glareolus)

Abstract

Habitat fragmentation causes negative population trends or even local extinction in many species. Understanding the role of fragmentation on behavior and space use of animals is an essential part of revealing the mechanism behind observed population declines. We studied experimentally the effects of small-scale habitat fragmentation on the distribution and movement of bank voles (Myodes glareolus) in seminatural enclosures. We predicted that besides habitat structure, availability of two resources, food for both sexes, and receptive females for males, determine individual distribution. We manipulated female density (either 0, 4, or 12 per enclosure) and followed movements of radio-collared males. We also studied the effect of unequal food distribution between the fragments on vole distribution. The habitat of 0.25-ha enclosures was manipulated by forming either one large, two medium-sized, or four small habitat patches surrounded by an inhospitable matrix. Female density and distribution clearly affected male spacing behavior. Males had larger home ranges in the medium female density enclosures. Furthermore, the use of the inhospitable and risky matrix area increased with habitat fragmentation. Food supplementation improved individual condition measured as body mass but did not affect breeding success. Our experiments demonstrated that both small-scale habitat fragmentation and resource distribution affect the behavior and condition of individuals. Increased fragmentation led to increased risk taking in both mating and foraging behavior. This should have direct survival and fitness consequences, and therefore our results may be extrapolated to populationlevel consequences of habitat fragmentation.

Infanticide effects on behavior of the bank vole (Myodes glareolus) in the fragmented breeding habitat

“…In a study on the effects of habitat fragmentation on meadow voles, Collins and Barrett (1997) found that males in fragmented treatments had larger home range sizes than males in nonfragmented treatment. Also, longer movements in more fragmented habitats have been observed in other experiments with rodents (Diffendorfer et al 1995;Andreassen et al 1998;Haapakoski and Ylönen 2010). High avian predation pressure which led to low male survival is likely to bias survival of the males toward less active males, and probably most active, bold males died already during radio-tracking.…”

“…In addition, Ostfeld (1990) suggested that the availability of receptive females is more important for the movements of males than the distribution of other resources. Males took risks by moving in the matrix probably because seeking for receptive females (Haapakoski and Ylönen 2010) which were distributed evenly across patchy habitat in the fragmented treatment. In particular, the noninfanticidal males seemed to move more outside the habitat patch also in the nonfragmented treatment.…”

“…Two radio-collared males, either infanticidal (Infa+) or noninfanticidal (Infa−), were released singly into random, opposite corners of the habitat patch/patches in fragmented or nonfragmented enclosures. Based on earlier experiments, we assumed that the females gave birth around the time of male release (Haapakoski and Ylönen 2010).…”

“…If the habitat consists of small patches, both strategies are likely to change (Wolff 1993;Banks et al 2007). If males aim for increasing their reproductive success by increasing the number of matings, they need to cross the risky matrix areas more often (Haapakoski and Ylönen 2010). Females breeding in a small fragment, depending on the size of the patch relative to breeding territory, are more likely to stay close to the nest site as the risky matrix hinders wider foraging trips.…”

Genetic variations of Turkish bank vole, Myodes glareolus (Mammalia: Rodentia) inferred from mtDNA

“…This differentiation would be therefore associated to the deciduous forest fragmentations, which appeared during the last cold periods of the Quaternary. As mentioned in the studies of Gerlach & Musolf (2000), and Haapakoski & Ylonen (2010), the constraints on mating and foraging behaviors resulted by habitat fragmentations. Thus, this fragmentation might have led to variations of the bank vole populations distributed throughout the Black Sea region also.…”