ARE THERE CLUMPS IN BODY-SIZE DISTRIBUTIONS

I examine the suggestion of Holling (1992) that distributions of body sizes for animals show clumps corresponding to basic biotic and abioti c processes operating at different scales in time and space. This is d one by comparing the properties of observed sample distributions with what is obtained from computer-generated samples taken from distributi ons with different numbers of modes. A combination of kernel density e stimation and smoothed bootstrap resampling provides a test for whethe r a distribution with k + 1 modes fits significantly better than a dis tribution with k modes. The analysis of three data sets discussed by H olling shows sample size distributions that are consistent with the hy pothesis that the underlying distributions are unimodal or bimodal. A fourth data set has a sample distribution that seems unusual even for observations from a distribution with eight modes.