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Providing evidence to improve practice

Individual study: Performance of translocated hazel dormice Muscardinus avellanarius in the Mendip Hills, Somerset, England

Published source details

Bright P.W. & Morris P.A. (1994) Animal translocation for conservation: performance of dormice in relation to relase methods, origin and season. Journal of Applied Ecology, 31, 699-708


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Provide supplementary food during/after release of translocated mammals Terrestrial Mammal Conservation

A before-and-after study in 1991 in a woodland reserve in Somerset, UK (Bright & Morris 1994) found that translocated common dormice Muscardinus avellanarius gained weight after being provided with supplementary food after release. Translocated common dormice lost an average 0.30 g/day before supplementary food was provided but then gained 0.20 g/day after supplementary food provision commenced. The study was conducted along a 9-ha strip of woodland and scrub. Seven dormice were translocated between 30 May and 28 June 1991. Dormice were weighed every 2–3 days up until 10–14 days after release. Six of the seven dormice were provided with supplementary food (sliced apple, sunflower seeds, fruits of trees from the study site) for 5–8 days. Dormice were caught in the morning and placed at the release site in the nest box in which they had been captured, by early afternoon of the same day.

(Summarised by Ricardo Rocha)

Release translocated/captive-bred mammals at a specific time (e.g. season, day/night) Terrestrial Mammal Conservation

A study in 1991–1992 in a woodland reserve in Somerset, UK (Bright & Morris 1994) found that common dormice Muscardinus avellanarius translocated during spring had lower survival rates, lost more weight and travelled shorter distances than dormice translocated during summer. Overall, five of seven dormice (57%) released in spring survived the first 10 days post release compared to seven of eight (80%) dormice released in summer. Common dormice translocated in spring lost more weight (0.30 g/day) than did dormice translocated in summer (0.14 g/day). However, they moved shorter daily distances from their release site (spring translocation: 119 m/day; summer translocation: 292 m/day). Seven dormice were translocated in spring (between 30 May and 28 June 1991) and 10 in summer (between 24 August and 30 September 1992) to a 9-ha strip of woodland and scrub. Dormice were caught during the morning, moved to the release site and placed there by early afternoon, in the nestbox in which they had been captured. Individuals were fitted with radio-transmitters and followed for 10–20 nights. Dormice were weighed until 10–14 days after release.

(Summarised by Ricardo Rocha)

Use holding pens at release site prior to release of captive-bred mammals Terrestrial Mammal Conservation

A controlled study in 1992 in a woodland reserve in Somerset, UK (Bright & Morris 1994) found that captive-bred common dormice Muscardinus avellanarius lost weight after release into holding pens whereas wild-caught translocated dormice gained weight. The body mass of captive-bred common dormice decreased after release into holding pens by 0.23 g/day, whereas that of translocated wild-caught dormice increased by 0.12 g/day. After release from the holding pens, both captive-bred and wild-caught translocated dormice lost a small amount of weight (see original paper for details). The study was conducted along a 9-ha strip of woodland and scrub between 24 August and 30 September 1992. Eight captive-bred and six wild-caught dormice were held in a pre-release pen for eight nights, and then released into the wild. The pre-release pen (0.45 m wide, 0.5 m deep and 0.9 m high) was constructed from 1-cm2 weldmesh and had food and water. Dormice were released in the same groups as they were found in nestboxes or in which they had been living in captivity. All individuals were weighed 10–14 days after release.

(Summarised by Ricardo Rocha)

Use holding pens at release site prior to release of translocated mammals Terrestrial Mammal Conservation

A controlled study in 1992 in woodland edge in Somerset, UK (Bright & Morris 1994) found that translocated common dormice Muscardinus avellanarius held in pens before release gained weight after release, whereas dormice released directly into the wild lost weight. The body mass of dormice released from pre-release pens increased after release by 0.12 g/day, whereas dormice released directly into the wild lost 0.14 g/day. The study was conducted along a 9-ha strip of trees and shrubs in August–September 1992. Six wild-caught dormice were placed in pre-release pens and 10 wild-caught dormice were released directly into the wild on their day of capture. Pre-release pens (0.45 m width, 0.5 m depth and 0.9 m height) were constructed from 1-cm2 weldmesh. Nest boxes, food and water were provided. Dormice stayed in pens for eight nights before release. Dormice were monitored by radio-tracking and were recaptured and weighed 10–14 days after release.

(Summarised by Ricardo Rocha)