An examination of some statistical tests used in the analysis of mark-recapture data

The effects of marking and capture on recapture frequencies of butterflies

As a preliminary to a population study using markrelease-recapture techniques, specimens of the Satyrid buttfly Melanargia galathea (L.) were subjected to a number of marking and capture techniques. Although the adults are thought to display both aposematic and cryptic coloration, the use of marks of different sizes and colours had no significant effect on recapture frequencies. However, repeated disturbance due to capture was found to significantly reduce recapture frequency. The influence of the different techniques on recapture frequencies could not be detected reliably by excessively low recapture rates, or by comparisons to Poisson distributions. It is suggested that these comparisons are of limited value as measures of the suitability of a marking or handling scheme. Subsequent work showed that capture affected recapture rates of several other species. Moreover, these effects could not be readily predicted from knowledge of the biology of these species. The implications of these findings are discussed.