ANNUAL GROWTH-RATES IN NEWLY ESTABLISHED POPULATIONS OF THE BUTTERFLYPARARGE AEGERIA

1. The likelihood of range changes in the event of climate change make s study of the foundation and establishment of populations of particul ar relevance and interest. 2. The butterfly Pararge aegeria has expand ed its range in Britain over many decades. Since 1985, ten monitored s ites in eastern England have been colonized and the pattern of populat ion growth examined. 3. Geometric annual growth rates in the establish ing populations were initially, on average, three- to fourfold but sub sequently declined. The decline provides possible evidence that densit y-dependence limits final population densities, but other explanations are possible.