Development of the Captive Breeding Programme for the Re-Introduction of Hazel Dormice (Muscardinus Avellanarius) in the United Kingdom, 1982-1994
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Advances in Zoology and Botany 5(3): 25-32, 2017 http://www.hrpub.org DOI: 10.13189/azb.2017.050301 Development of the Captive Breeding Programme for the Re-introduction of Hazel dormice (Muscardinus avellanarius) in the United Kingdom, 1982-1994 Dot Eaton1,*, Martin Hicks2 1Berkshire, UK 2Hertfordshire Ecology, Environment Department, Hertfordshire County Council, UK Copyright©2017 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract In 1981 the lead author wished to instigate a dormouse breeders in the group donate individuals each year breeding programme for an indigenous and endangered to re-introduction projects, supervised by The People’s Trust British mammal species that was known to have suffered a for Endangered Species. significant decline in numbers. Captive breeding to provide Keywords Common or Hazel dormouse, Muscardinus individuals for potential re-introductions was considered the avellanarius, Captive Breeding most appropriate approach to helping the re-establishment of wild populations from where they had previously been lost or declined. The selected species needed to be harmless to the environment and small so that expensive techniques were not required. The intention was to generate a sufficiently large 1 . Introduction and genetically diverse captive population which would In the United Kingdom there is one indigenous species of supply a formal re-introduction programme into appropriate dormouse, the Common or Hazel dormouse Muscardinus sites. Having addressed the reasons for previous declines of avellanarius. This is a small, mouse-sized mammal, adults local extinction, released dormice would provide the basis weighing between 15 - 30grammes. It is much smaller than for new populations. Given the resources available, the the only other species of dormouse present in the UK, the Fat Common or Hazel dormouse, Muscardinus avellanarius was or Edible dormouse Glis glis, a rat-sized mammal of 50-250g considered to be a suitable species for this programme. and a recent (1902) introduction. Glis remains largely Successful captive breeding had not been achieved localised to the Chiltern Hills and although it is spreading it previously. The Mammal Society Dormouse Survey 1975– is not considered to represent a threat to the native dormouse. 79 demonstrated it had been lost from seven counties in the An adult Hazel dormouse has bright golden or orange-brown UK during the previous 100 years [1]. A nocturnal and fur and a semi-prehensile tail. It has long whiskers, round secretive species little was known about the detailed dietary ears and large black eyes set on the side of its head. It is requirements or behaviour of the common dormouse. The nocturnal and hibernates over winter for up to seven months establishment and development of the breeding colony of the year. In the late 19th Century Hazel dormice were to be enabled observations of their nocturnal activity in captivity. found throughout most of the wooded countryside in This was observed at very close quarters and behaviour England and Wales. However, the Hazel dormouse Survey related to feeding, mating, juvenile development and other 1975-79 organised by The Mammal Society (Hurrell and seasonal changes in activity was noted. Initially there were Macintosh 1984) [1] found it had disappeared from seven numerous juvenile deaths within the colony, usually in counties in the UK. It is fully protected under the Wildlife spring and autumn but with changes to the temperature and Countryside Act 1981 being included on Schedules 5 regime immediately prior to and post hibernation, this and 6. It was hoped that the establishment of a successful mortality reduced. By 1992 the numbers in the captive captive breeding colony would supply dormice for breeding colony grew to 33 individuals, sufficient for the re-introductions to help address the decline in the species. first trial re-introduction of 11 individuals to take place in Hertfordshire following the IUCN guidelines [4]. Following further breeding and survival success, further 2 . Objectives re-introductions were supported and by 1995 the colony had risen to 97 individuals. In that year the Common Dormouse Having identified the Hazel dormouse as a suitable species Captive Breeders Group was formed and currently six to support with a captive breeding programme, the project 26 Development of the Captive Breeding Programme for the Re-introduction of Hazel dormice (Muscardinus avellanarius) in the United Kingdom, 1982-1994 identified a number of requirements and research aims: 1. A thirty-year-old section of the wood due to be coppiced 1. To determine on the optimal physical conditions for in 1983/84. This was dark and overshadowed by ash keeping Hazel dormice in captivity. This would reflect Fraxinus excelsior. There was much bare ground with known food and habitat preferences of wild dormice; only moss and young ash seedlings. 2. To acquire an initial stock of Hazel dormice to establish 2. A four-year-old coppice last coppiced in 1977/8. This a captive breeding colony; coupe supported abundant hazel Corylus avellana two 3. To maintain suitable genetic diversity of the breeding or three metres high. The ground flora was dominated colony; by bramble Rubus fruticosus up to a metre and sanicle 4. To ensure appropriate husbandry to maintain the health Sanicula europaea was also present. Honeysuckle of individuals suitable for breeding; Lonicera periclymenum was present but still at a young 5. To record health, mortality and loss; stage of growth and mostly at ground level. 6. To observe breeding and seasonal changes in behavior; 3. A coupe which had been recently coppiced in 1979/80. 7. To ensure the breeding colony reached sufficient size to This was covered with young hazel regrowth of 30cm enable individuals to be used for a re-introduction; and a ground flora consisting of ash saplings, sanicle, 8. To establish a wider captive-breeding programme to clumps of stinging nettle Urtica dioica, rosebay willow support re-introduction projects nationally. herb Chamerion angustifolium and thistle Cirsium sp. with quite a lot of bare patches of ground. The surveys demonstrated the habitat diversity in 3. Project Delivery composition and structure within the wood and in particular the dense vegetation of the younger age coppice. This is 3.1. To Determine on the Optimal Physical Conditions consistent with the type of vegetation considered to be for Keeping Hazel dormice in Captivity. This Would important for Hazel dormice and confirmed the need to Reflect Known Food and Habitat Preferences of reflect this in the captive colony in order to support Wild Dormice successful breeding. Habitat Requirements in Captivity In the early 1980s there was little information recorded formally on the food preferences of dormice or habitat requirements. However, Hurrell (1980) [2] had noted Hazel dormice could most often be found in shrubby woodland with hazel. Therefore, part of the investigation was to study different stages of re-growth found in a woodland site known to support Hazel dormice. Wallis Wood in Surrey was one of the few remaining managed hazel copses in the south of England, owned by the Surrey Wildlife Trust and coppiced on a ten to twelve-year rotation. Coppicing is an ancient practice dating back well over 1000 years where areas of trees and shrubs (a ‘coupe’) are felled to nearly ground level to encourage regeneration of a future harvestable regrowth in the form of many straight stems. These were cut again in anything from three to 25 years depending on the proposed use of the ‘underwood’ crop, such as for hurdles or firewood. Standard, high-canopy trees were also present (around 10-12 per acre) providing a timber crop, but not sufficient to create extensive shading of the coppice. This management creates significant habitat diversity within woodland including very dense regrowth of between three and around seven years old, which along with ground flora and other vegetation provides an impenetrable shrub layer habitat valued by variety of wildlife including birds such as warblers and nightingales, as well as small mammals such as the Hazel dormouse. In Wallis Wood the layout of coppice coupes and their ages can be seen in Figure 1. In 1982/3 three ages of coppice were surveyed for plants likely to be used by dormice. These Figure 1. Map of Wallis Wood, Surrey showing layout of coppice were: compartments and winters when cut. Advances in Zoology and Botany 5(3): 25-32, 2017 27 3.2. Development of Breeding Enclosures with BBC cameraman Owen Newman who had recently trapped and filmed a dormouse giving birth. Subsequently a Following this research, in 1982/3 an outdoor enclosure license from the Nature Conservancy Council was obtained was constructed at Chessington Zoo within a former large by D. Eaton to trap and take wild dormice with O. Newman animal cage. This was subsequently improved by the for the purposes of establishing captive breeding group. In construction of a cage measuring four metres by two metres 1983 three dormice were trapped in Wiltshire using and two metres high. It was planted out with young hazel, Longworth small mammal traps to provide the first bramble and rosebay willow herb. This was attached to a one individuals of the captive colony. cubic metre enclosed feeding station, lit with infra-red light. The dormice would occasionally run in to take food or water, which enabled some nocturnal sightings but no natural behavioural activity could be seen. The external cages were not illuminated; therefore the dormice could not easily be seen at night. Due to a change in circumstances, the breeding colony was moved to Windsor Safari Park in 1988 when the dormice were moved into a shed which was divided into four internal compartments.