Does Competition Drive Dispersal?

What distances would animals be expected to disperse if the only cost to staying on the natal site resulted from competition for resources limiting to reproduction? In such a situation the b est" dispersal distance would be zero, but the constraint of competition would prevent many individuals from achieving this ideal; the actual dispersal distances would be shaped by population demography. The models I describe predict the distribution of dispersal distances as a function of home range turnover probability for animals that move to the first uncontested home range they encounter and no farther. The models provide a good match to data for some, but not all, avian and mammalian data sets, suggesting (1) that competition for resources limiting to reproduction may be the primary factor driving dispersal, and (2) that the action of inbreeding avoidance, habitat selection, and other processes suggested to influence dispersal distances can be detected as deviations from these model predictions.