Habitat specialization interacts with habitat amount to determine dispersal success of rodents in fragmented landscapes

Habitat specialization is considered one of the most important determinants of species vulnerability to habitat loss and fragmentation because it defines species dispersal ability and thus the degree of isolation of populations. Further, dispersal success of habitat-specialist species depends on the distance between fragments, which is conditioned on the total amount of habitat in the landscape. Here, we compared the influence of total habitat amount on dispersal success and abundance patterns of 2 habitat specialists and 1 generalist Atlantic Forest rodent. We investigated short-term population dynamics in a continuous forest landscape as well as in 6 small forest fragments located in 2 landscapes differing in the amount of forest cover (30% and 50%). Further, we analyzed the influence of fragment size on population density in the fragmented landscapes. Number of immigrants and abundance of both habitat-specialist species decreased remarkably in small patches of the 30% forest cover landscape compared to both more-forested landscapes, and both species showed a patch-area effect on density in this landscape. In contrast, the generalist species showed similar immigration rates in continuous forest and patches of the less-forested landscape, high temporal and spatial variability in abundance, and no patch-area effect in any of the landscapes. The results provide empirical support for the interaction between habitat specialization and habitat amount in determining the response of species to habitat loss, showing that the response of habitat specialists-in contrast to generalists-is governed by the landscape-wide amount of habitat.