There is no place like home: High homing rate and increased mortality after translocation of a small mammal

Animal translocation is a popular tool in wildlife management. It is frequently used to solve human-animal conflicts and recently has been applied as a mitigation tool when animals inhabit land desired for development. However, its success is uncertain and involves risks. In order to provide useful information to wildlife managers about the effect of translocation distance on animal movement behavior and survival, we translocated 40 Long-haired field mice (Abrothrix longipilis) at different distances from their territories (0-1,300 m) in central Chile and recorded the location and survival of each mouse over 3 days. Translocated animals showed low release site fidelity and traveled two- to four-fold longer distances than the nontranslocated group. Only mice translocated at shorter distances (100 m) oriented their movement toward their origin site and had a high probability of homing (80 %). There were threshold distances from after which homing and traveling strongly decreased. All individuals released close to their capture site (≤100 m) remained alive, while mortality reached 22 % at longer translocation distances, principally as a result of fighting between rodents. Therefore, long translocation distances prevented short-term homing and decreased traveled distances (a desirable outcome), but risks associated with conspecific encounters need to be avoided. Because mice showed a high motivation to explore surroundings, it is advisable to release animals in sites with alternative places to colonize. Our results emphasize the need for a strong justification in wildlife translocation projects and the development of alternative techniques to improve animal welfare and conservation.