Displacing and translocating hazel dormice (Muscardinus avellanarius) as road development mitigation measures

Abstract

Road development can remove valuable wildlife habitat and reduce habitat connectivity. Where such works impact on European Protected Species in the UK, such as hazel dormice (Muscardinus avellanarius), mitigation is required to satisfy the relevant Statutory Nature Conservation Organisation licensing process. The study described here concerns the removal of dense road verge landscape planting occupied by hazel dormice prior to the construction of a new road junction and slip roads on a dual carriageway in Wales. Pre-construction monitoring started in May 2007, followed by vegetation clearance between August and September. Dormice were displaced into retained habitat through maximum daily vegetation clearance of 30 m lengths (varying widths), in parallel with translocation. This process resulted in the discovery of 48 natural (i.e. not within a nest box) dormouse nests, and the capture of 29 dormice for translocation; 90% were successfully released. Whilst within soft-release cages prior to release, dormice preferred a diet of blackberries (Rubus fruticosus agg.) and freshly picked hazel (Corylus avellana) nuts, prompting a recommendation for early Autumn (mid-August – September) as the ideal translocation season. Other recommendations for displacing and translocating dormice are provided, albeit limited in the absence of comprehensive pre-construction, and post-translocation monitoring.