Interpatch movements in spatially structured populations: a literature review

We used published data of individuals moving among habitat patches to answer questions pertaining to frequency of interpatch movements and subsequent effects on population dynamics. A review of 415 published articles produced data for 89 species-system combinations where movements were recorded in sufficient detail to include in our analysis. The percentage of individuals in a population that moved among habitat patches ranged from 0.00 to 93.00%, with a mean of 16.84%. Scaling this statistic by generation time yielded a mean movement rate of 15.45 +/- 3.27% per generation. The relatively low movement rates suggest that subpopulations, except those of invertebrates, should not be highly integrated. Less than half of the empirical studies reported on the population effects of interpatch movement. Of these, thirty-three studies yielded population effects on 34 individual species in 45 species-systems. They reported movement having a positive effect 28 times, a negative effect twice and a neutral effect 14 times. Despite its importance, relatively few studies document rates of interpatch movement and far fewer determine population level consequences of these movements. This deficiency limits our ability to understand the dynamics of spatially structured populations and apply that knowledge to conservation efforts.