Effects of habitat fragmentation on Eurasian red squirrel (Sciurus vulgaris) in a forest landscape

We studied the effects of habitat fragmentation, measured as forest stand s ize and isolation, on the distribution of Eurasian red squirrels (Sciurus v ulgaris). Squirrel density was surveyed during four years in 46 forest stan ds (0.1-500 ha) in a forest landscape in south-central Sweden. The only fac tor that significantly influenced a density index was the proportion of spr uce within a habitat fragment. Neither fragment size nor degree of isolatio n were significant. Furthermore, none of the interactions with year were si gnificant, suggesting the same pattern in all four years. Thus, the effect of habitat fragmentation in this study seems to be only pure habitat loss, i.e. halving the proportion of preferred habitat in the landscape should re sult in a halving of the red squirrel population. Therefore, the landscape can be viewed as functionally continuous for the squirrels, although the pr eferred habitat was divided into fragments. The most likely explanation for the difference between this study and other studies on squirrels that foun d effects due to habitat fragmentation is a combination of shorter distance s and less hostile surroundings in our study area. To identify landscape ef fects requires multiple studies because single studies usually consider onl y one landscape.