Use tranquilizers to reduce stress during translocation
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Translocation of mammals can cause elevated stress levels. This may affect post-release survival (e.g. Beringer et al. 2002). Tranquilizers may be administered during the translocation process in order to reduce stress to captured mammals.
Beringer J., Hansen L.P., Demand J.A., Sartwell J., Wallendorf M. & Mange R. (2002) Efficacy of translocation to control urban deer in Missouri: costs, efficiency, and outcome. Wildlife Society Bulletin, 30, 767–774.
Supporting evidence from individual studies
A controlled study in 1997 on a farmland site in northern France (Letty et al. 2000) found that using tranquilizers to reduce stress during translocation did not increase post-release survival of European rabbits Oryctolagus cuniculus. The re-sighting rate of rabbits that had been tranquilized over seven weeks after release did not differ significantly from that of non-tranquilized rabbits over the same period (data reported as statistical model results). In January 1997, a total of 104 rabbits were translocated from Parc-du-Sausset to an area of cultivated fields and pasture in Héric, 400 km away. Of these, approximately half were tranquillized just after capture using two intra-muscular injections of carazolol (0.1 mg/kg). Roughly half the tranquilized and half the non-tranquilized rabbits were acclimatised in 100-m² enclosures for three days prior to release. Survival was estimated from nocturnal spotlight re-sighting sessions conducted every evening during the first week following release. Thereafter, monitoring was reduced to twice/week for a further six weeks, until late-February.Study and other actions tested