Changes in the status of dormice species in Latvia over the last three decades

The first assessment of the status of dormice in Latvia, with emphasis on their distribution, was made in 1993. In accordance with the methodology used within the LIFE-IP LatViaNature project (2020–2028), to set favourable reference values (FRVs) for species range and population, the early 1990s was chosen as  the baseline for evaluating population trends of species listed in the Habitats Directive, as this was a socio-economic turning point in  the country. The next milestones were 2004 (Latvia joined EU) and the present time. Knowledge about dormice, especially the Forest and Hazel Dormouse, has considerably improved. Since then, one of four dormice species, the Garden Dormouse, has vanished from Latvia. No records of this species are known since the mid-1990s, despite widespread use of nest boxes for monitoring dormice. The limited ranges and population sizes of the Forest Dormouse and Edible Dormouse within the country are related to their occurrence here at their northern limits of distribution. Among other dormice species, the Hazel Dormouse is the most numerous and widespread. Currently, it has three disjunct populations, one of which has probably  vanished. Dormice monitoring as part of the national biodiversity monitoring programme started only in 2016. Therefore, long term population trends  are unknown.  Nest box occupation by the Forest Dormouse has been relatively stable, but in the Hazel Dormouse it decreased in 2019–2021 compared to 2017–2018, most probably, due to mild winters.