Many parks represent insular areas of habitat and the movement of animals across park boundaries can be critical to park wildlife populations. I use computer sitmulation models in order to analyse factors affecting the movement and density of animals in patches of habitat (Buechner, 1987b; Stamps et al., 1987; in press). The results suggest that the perimeter:area ratios and edge permeability of parks, the appearance and stopping patterns and habitat preferences of moving animals, and the relative size of dispersal sinks and source pools can all potentially influence the direction and magnitude of the movements of animals across the park boundaries. The results suggest that scientists interested in park and reserve design need to consider other factors than just the size of potential sites, particularly park perimeter: area ratios. The simulations also suggests a strategy for solving some types of conservation and control problems by manipulating sinks or pools: (1) identify which factors can be practically altered in a given situation, (2) evaluate those factors to estimate their current levels, and (3) focus on the factor which is nearest the lower end of its range of values.