Testing Leopold's Law of Dispersion on Cottontail Rabbits Occupying Shrubland-Grassland Ecotones

Abstract

Leopold's Law of Disperson, commonly referred to as the principle of edge, is a long-held tenet of wildlife management. The law suggests that a direct linear relationship exists between the densities of edge-benefitted species and the quantity of edge. We tested three hypotheses derived from edge theory and used cottontail rabbits (Sylvilagus floridanus) as our animal model. Our hypotheses were: (1) an edge-benefitted species will exist in the absence of edge, (2) each species has an edge saturation value (maximum length of edge/area) where additional edge will not increase species density, and (3) there exists a distance from edge, defined as the radius of full use, beyond which a species' use of an area declines. Cottontail rabbits were found in the absence of edge only with shrubland habitat. Cottontails did not exhibit an edge saturation value. The radius of full use for cottontail rabbits was undefined and 3.1 yds in shrubland and grassland, respectively. Data collected in this study did not support current theories concerning the relationship between length of edge and species density.