When is a dormouse ‘Endangered’? Continued population decline of Hazel Dormice (Muscardinus avellanarius) in Great Britain. (Poster)

It is important to monitor species populations to identify changes in Red List assessment, whether increases from conservation or continued declines. This can be more difficult when there are multiple modelling options available. Using data from the National Dormouse Monitoring Programme, provided by the People’s Trust for Endangered Species, we explore the change in British Hazel Dormice (Muscardinus avellanarius) populations using two appropriate generalised additive models. The first uses the negative binomial distribution, and second the Poisson distribution, with a fixed effect of month included. Both models indicate that dormice have declined by >70% between 1994 and 2018 in Great Britain, indicating a continuation of the chronic decline of the species. Our models do not differ significantly in their evaluation of the population trend, but do indicate different Red List categories, leading us to ask: when is the dormouse population considered ‘endangered’?