The recovery of an ecosystem in response to a restoration program that relies on natural processes may be characterized by heterogeneous changes in species composition and structure. In most cases, such variability is natural and should even be welcomed. However, variability that arises from a specific restoration site, as opposed to randomly from all sites, may indicate problems with the restoration process and may jeopardize the outcome of a project. Here, we describe a technique to flag those sites and assemblages that tend to develop aberrantly. We use data on plant and animal assemblages, collected during routine monitoring operations over several surveys on a chronosequence of rehabilitating dune forests. Using this technique, we show that a bird assemblage on one of the sites at our study area on the coast of southern Africa tends to develop slower than expected. This site is situated farther than others from potential source areas (intact forests) and closer to human habitation. In essence, the technique uses a permutation test to identify ecological variables and assemblages that tend to be more variable than expected. It then focuses on these to identify specific aberrant sites. The technique allows management to concentrate scarce resources to determine the causes of aberrant changes, as well as possible mitigating actions, for specific sites instead of across the board. This cost-efficient rapid assessment technique will lead to improved chances of restoration success. It may be applied in all projects where a chronosequence of sites can be sampled repeatedly, as is often the case in post-mining restoration.