The effect of translocation on movement behaviour--a test of the assumptions of behavioural studies.

Animal movement behaviour is intensively investigated with capture-mark-recapture studies. For the analysis of such experiments, the influence of marking technique, handling and translocation of marked animals on movement pattern is of crucial importance since it may mask or overrule the effects of the main research question. Here we present a capture-mark-recapture experiment on the movement behaviour of the blue-winged grasshopper Oedipoda caerulescens. We analyzed the influence of translocation of individuals from familiar to unfamiliar sites. Our study clearly demonstrates a significant influence of translocation to unfamiliar sites on the movement behaviour of O. caerulescens. Translocated individuals moved longer distances, showed smaller daily turning angles, and thus movements were more directed than those of resident individuals. The effect of translocation on daily moved distances was most pronounced on the first day of the experiment. We thus conclude that at least for the first day after translocation, movement behaviour is significantly influenced by translocation itself. Data ignoring this influence will be unsuitable for the prediction of dispersal behaviour, habitat detection capability or habitat preference.