The homing behavior of red deer: A GPS assisted translocation experiment

Abstract

Abstract Background Many animals move back to their home area (i.e., ‘homing’) after translocation to sites further away. Such translocations have traditionally been used in behavioral ecology to understand orientation and migration behavior of animals. The movement itself can then be followed by marking and recapturing of animals or by tracking, e.g., using GPS systems. Most detailed studies investigating this behavior were conducted with smaller vertebrates (e.g., birds, amphibians and mice), whereas information on larger mammals, such as red deer, is sparse. Methods We conducted GPS assisted translocation experiments with red deer at two sites in the Czech Republic. Individuals were translocated over a distance of about 11 km and their home journey was tracked. We used circular statistics to test for significant homeward orientation at 100, 500, 1000 and 5000 m distance to the release site. In addition, we applied a Lavielle trajectory segmentation, identifying different phases of the homing behavior. Results Thirty-one out of 35 translocations resulted in successful homing with a median time of 4.75 days (range: 1.23 to 100 days). Animals significantly oriented towards home immediately after release and again when they came closer to home; however, they did not show significant orientation at the distances in between. We were able to identify three homing phases, an initial ‘exploratory phase’, followed by a ‘homing phase’ which sometimes was again followed by an ‘arrival phase’. The ‘homing phase’ was characterized by the straightest paths and fastest movements. However, variation between translocation events was considerable. Conclusions We show good homing abilities of red deer after translocation. Our results show the feasibility to conduct experiments with environmental manipulations (e.g., to impede the use of sensory cues) close to the release site. The homing behavior of red deer is comparable to other species and might represent general homing behavior patterns in animals. Follow up studies should further dissect and investigate the drivers of the individual variations we observed, and try to identify the sensory cues used during homing.