Translocation as a conservation tool to supplement relict bat colonies: a pioneer study with endangered horseshoe bats

Abstract

Relocation has become an important tool in conservation biology. So far little is known about the suitability of translocation to restore bat populations. We evaluated the conditions for suc- cessful translocations amongst 2 bat species: the greater horseshoe bat Rhinolophus ferrumequinum and the lesser horseshoe bat R. hipposideros. Both species underwent a dramatic decline in Western and Central Europe in the second half of the 20th century, but some populations have recently started to recover. Due to their sedentary habits, natural recolonisation of their formerly vast inhabited range advances only slowly. Translocation could solve this problem. In 2006, we conducted translocation experiments with 11 greater and 7 lesser horseshoe bats within Switzerland. Bats were captured at large colonies, released into relict colonies, radiotracked for up to 10 d and checked for presence dur- ing the following years. Ten out of the 13 individuals released at distances 40 km expressed homing tendencies. Within 3 d of release, 1 greater and 3 lesser horseshoe bats died (2 of shock). Lesser horseshoe bats seem to react very sensitively to translocation. Long-distance translocation of 2 greater horseshoe bats led to short-term settlement in the release area; since its translocation, the sole female released at long distance has been regularly observed in the receiver colony. Apparent species-specific differences in tolerance to translocation underline the necessity of studying the focal species instead of surrogate species in translocation projects.