Sampling error can cause false rejection of the core-satellite species hypothesis.

The distribution of patch occupancy (the proportion of suitable patches occupied by a species) in ecological communities is often unimodal with a mode at minimum patch occupancy values, or bimodal with two local maxima that correspond to the minimum and the maximum patch occupancy. The bimodal distribution is predicted by a metapopulation model known as the core-satellite species hypothesis, but could also be an artifact caused by spatially restricted sampling from a unimodal distribution. A sampling artifact with the opposite effect, producing samples with a unimodal patch occupancy distribution from communities with a bimodal distribution is described here. This artifact is particularly likely to occur when the accuracy of sampling varies among species, as is often the case.