Improving translocation success: an experimental study of anti-stress treatment and release method for wild rabbits

Published source details Letty J., Marchandeau S., Clobert J. & Aubineau J. (2000) Improving translocation success: an experimental study of anti-stress treatment and release method for wild rabbits. Animal Conservation, 3, 211-219.
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This study is summarised as evidence for the following.

	Action	Category
	Use tranquilizers to reduce stress during translocation Action Link
	Provide supplementary food during/after release of translocated mammals Action Link
	Use holding pens at release site prior to release of translocated mammals Action Link

Use tranquilizers to reduce stress during translocation

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.

(Summarised by: Ricardo Rocha)
Provide supplementary food during/after release of translocated mammals

A controlled study in 1997 in a mixed pasture and cultivated fields farmland site in northern France (Letty et al. 2000) found that translocated European rabbits Oryctolagus cuniculus provided with supplementary food in holding pens for three days prior to release had higher female survival rates immediately following release compared to rabbits released directly, but male survival rates did not differ. During the first day after translocations, the survival rate of female rabbits released from pre-release pens with supplementary food was higher (100%) than that of females released directly into the wild (83%) and male rabbits released from release pens (78%). The survival rate of male rabbits released from pre-release pens with supplementary food (78%) was not significantly different to male rabbits released directly into the wild (92%). One hundred and four rabbits were translocated from Parc-du-Sausset to a 150-ha area of cultivated fields and pasture in Héric, approximately 400 km away in January 1997. Of these, roughly half were acclimatised in eight 100-m² enclosures (fence height: 1 m), for three days prior to release. Rabbits were provided supplementary food while in pens. Survival was estimated by night-time relocation of ear-tagged rabbits using a spotlight, daily in the first week after release and twice a week until late February 1997.

(Summarised by: Ricardo Rocha)
Use holding pens at release site prior to release of translocated mammals

A controlled study in 1997 in a mixed pasture and cultivated fields farmland site in northern France (Letty et al. 2000) found that keeping translocated European rabbits Oryctolagus cuniculus in holding pens for three days prior to release (and carrying out associated management such as supplementary feeding) increased survival rates of female, but not male rabbits immediately following release compared to rabbits released directly into the wild. During the first day after translocations, the survival rate of female rabbits released from pre-release pens was higher (100%) than that of females released directly into the wild (83%) and male rabbits released from release pens (78%). The survival rate of male rabbits released from pre-release pens (78%) was not significantly different to that of male rabbits released directly into the wild (92%). One hundred and four rabbits were translocated from Parc-du-Sausset to a 150-ha area of cultivated fields and pasture in Héric, approximately 400 km away in January 1997. Of these, roughly half were acclimatised in eight 100-m² enclosures (fence height: 1 m), for three days prior to release. Rabbits were provided with supplementary food. Survival was estimated by night-time relocation of ear-tagged rabbits using a spotlight, daily in the first week after release and twice a week until late February 1997.

(Summarised by: Ricardo Rocha)