Perceptual range and connectivity: exploring the effects of habitat changes on inter-patch dispersal paths

摘要

One of the effects of fragmentation is to increase inter-patch dispersal distance, increasing the risk of predation en-route. Perceptual range (the ability to detect habitat patches at a distance) is suggested as one characteristic that would be advantageous to a dispersing individual, by increasing the functional connectivity of the landscape and reducing the risk of dispersal mortality. Using an individual-based spatially explicit population model, we compared the effects of varying perceptual range on the dispersal flow pattern of a population of nuthatches (Sitta europaea L.) inhabiting two similar landscapes. We found that small changes in the landscape affected population sizes in two focal sites by setting up dispersal paths that guided nuthatches away from breeding habitat. The results suggested that, for some species, landscape connectivity may be influenced both by perceptual range and landscape heterogeneity. A counter-intuitive finding was that increasing perceptual range did not alwaysresult in an increase in dispersal success. We found that dispersal flow diagrams were essential in explaining the results. The effects of habitat changes were also detectable up to 4 km away, suggesting that the causes of local population changes may be not always be proximal to the site.