Effect of corridors and habitat edges on dispersal behavior, movement rates, and movement angles in Roesel's bush-cricket (Metrioptera roeseli)

One method proposed for moderating the negative effects of habitat isolation is the preservation or restoration of linear landscape elements that structurally link isolated habitat remnants. An understanding of how animals react to landscape elements and move through the landscape is vital for species management and theory development. To achieve this understanding, detailed information on movement rates and specific movement behavior of individual animals in different ecosystems is essential. In an experimental study, we investigated whether individuals of Roesel's bush-cricket ( Metrioptera roeseli) prefer to use corridors or move over the matrix when they leave a habitat patch. We examined whether movement rates and movement angles in corridors and matrix differed and whether individuals showed edge-avoidance behavior. Differences in these behaviors were analyzed in relation to the softness of habitat edges. We found that approximately 30% more individuals used the corridor than would be expected if dispersal behavior was random. All individuals using the corridor as a dispersal route moved to the end of the corridor and into the surrounding habitat, which is 1000% more than would be expected if dispersal was random. The edge type ( hard or soft) did not influence whether individuals moved through corridors or the matrix. Individuals that moved through the corridor moved straighter but slower than individuals that moved over the matrix. A higher movement rate over the matrix than through corridors may be explained by an increased risk of predation, starvation, or dehydration in the open habitat causing individuals to move more quickly toward the higher vegetation. Our results suggest that individuals avoid the edge and the matrix and that the corridor is a preferred alternative for dispersal. We conclude that for this species, and probably other similar species of Orthoptera, linear elements in the form of corridors have a positive influence on the individual's dispersal through the landscape. This demonstrates the value of corridors in reducing the negative effect of habitat fragmentation on the persistence of local species.