Effects of landscape composition on predation rates at habitat edges

Abstract

All landscapes are mosaics of habitat patches of different types (Forman and Godron, 1981). Therefore, there will always be edges between habitat patches in a landscape. These habitat edges may be associated with a higher diversity of plants and animals, traditionally called an edge effect (Odum, 1971). However, the current use of the edge-effect concept summarizes a diverse group of phenomena that occur in habitat edges (Harris, 1988; Yahner, 1988; Angelstam, 1992). For example, interaction between different organisms living in different habitat patches in the landscape mosaic may sometimes cause effects related to habitat edges (Janzen, 1986; Wilcove, McLellan and Dobson, 1986). Predator—prey interaction might be related to habitat edges. However, the relationship between predation rate and habitat edge depends on the specific habitat use and density of the potential nest predators, as well as the configuration of habitat patches in the landscape. Predators might increase the predation rate in habitat edges for several different reasons. First, the habitat edges might have a higher density of prey and the predators might view the edges as good foraging patches (Gates and Gysel, 1978). Secondly, the predators might use the habitat edges as traveling lines (Bider, 1968; Chapter 4) and therefore spend more time in the habitat edge than in other parts of the habitat patch.