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The bush cricket, Metrioptera bicolor Philippi (Orthoptera, Tettigoniidae) lives in a restricted area with grassland patches separated by mainly pine forest. The regional population dynamics can be described as a metapopulation with local extinctions and colonizations. I used inventory data in order to test the following hypotheses: (1) temporal variability of local population size should be negatively correlated with habitat heterogeneity, when habitat quality changes in relation to fluctuating weather conditions; (2) extinction risk should be higher on homogeneous habitat patches than on heterogeneous patches. Both hypotheses are convincingly corroborated and I find a compensatory effect between patch area and heterogeneity. Local extinctions may occur on large, but homogeneous patches, and local populations can survive quite well on small patches that contain a mosaic of several types of grassland vegetation with different humid conditions. I discuss the implications of these findings for the preservation of endangered species that are susceptible to regional stochasticity.

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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.Efecto de los Corredores y los Bordes del Hábitat Sobre la Conducta de Dispersión, las Tasas de Movimiento y los Ángulos de Movimiento del Grillo de Arbusto de Roesel ( Metrioptera roeseli ) Resumen: Un método propuesto para moderar los efectos negativos del aislamiento del hábitat es la preservación o restauración de los elementos del paisaje lineal que estructuralmente unen remanentes de hábitats aislados. El conocimiento de la forma en que los animales reaccionan a los elementos de paisaje y se mueven a través del paisaje es vital para el manejo de especies y la teoría del desarrollo. Para alcanzar este conocimiento, es esencial conocer información detallada sobre las tasas de movimientos y las conductas específicas de movimiento de animales individuales en diferentes ecosistemas. En un estudio experimental, investigamos si los individuos del grillo de arbusto de Roesel ( Metrioptera...