A Geometric Model of Vertebrate Dispersal: Tests and Implications

Buechner, Marybeth

A model of vertebrat natal dispersal is developed and compared to observed patterns of dispersal distances for a variety of animals. The model, which has the same basic formulation as Waser's 'competition model' of dispersal, is based on assumptions of the divisibitity of the habitat into discrete units capable of supporting a resident, and of a constant probability of a disperser stopping as it crosses each of these units. This probability is decomposed into the probability of settling and the probability of dying. Comparisons to observed data indicated that the model is adequate to describe the pattern treatments in that it is simple to manipulate mathematically, and it has parameters that are relatively easy to estimate from field data and are directly relevant to the behavior, ecology, and demography of dispersing animals. In addition, the theoretical distribution is in a form that makes statistical tests of the fit to observed data straightforward. Comparisons of parameter values and deviations from the geometric pattern between groups within taxa indicated that males and females may follow different patterns of dispersal. Comparisons among taxa indicated that mammmals and birds show consistent differences in dispersal distributions. These results are relevant to discussions of natal philopatry, inbreeding avoidance, and proximate mechanisms of dispersal.

A Geometric Model of Vertebrate Dispersal: Tests and Implications

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