The “Edge Effect” in Schizocosa Ocreata (Araneae: Lycosidae): A Reassessment

The relationship between local spider distribution patterns and environmental factors has been studied in a variety of species (Ndrgaard 1951; Dondale et al. 1969; Hallander 1970; Edgar 1971; Riechert 1974, 1976; Uetz 1976; Dondale 1977). Aspey (1976) stated that Schizocosa ocreata (Walckenaer) (formerly crassipes; Dondale and Redner 1978) was found in aggregations along a woodland-field ecotone, and suggested that unique microclimatic conditions and social interactions among conspecifics occurring within this area resulted in an "edgeeffect" for thisspider's distribution. He termed S. ocreata an "edge" species, implying it was found almost exclu- sively along ecotones. We were skeptical of Aspey's (1976) conclu- sions, since previous literature and prior experience with this species led each of us to the separate conclusion that S. ocreata is a forest- dwelling spider (Kaston 1948; Dondale and Redner 1978; Uetz 1976; Cady (in prep.)). In addition, Aspey's (1976) survey for S. ocreata appeared incomplete, as he did not report sampling within the adjacent woodland or field. Considering Aspey's (1976) elaborate behavioral arguments based on assumptions about the distribution of this species, we felt further study was necessary.