European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

This species is relatively common and widespread in central and southern areas of its European range. In some northern and northwestern regions, however, it is thought to be in decline owing to loss and fragmentation of habitat combined with changes in woodland management practices. Decline is suspected in a number of countries, including Estonia (where it is possibly extinct), Denmark, the Netherlands, Belgium (Flanders), Switzerland, and Great Britain, where in the latter a 48% decline over 10 years has been observed. However, it is not likely that an overall population reduction across a major extent of this species' range has approached the threshold for the population reduction criterion (30% in 10 years). In some areas, the status of this species is considered to be favourable. This species is therefore assessed as Least Concern for both Europe and the EU 27 Member States, but if declines become more widespread, it could qualify for Near Threatened status in the future. Increased long-term monitoring and conservation efforts in certain parts of its range are required.

The Hazel Dormouse (Muscardinus avellanarius) is generally widespread from the Mediterranean to southern Sweden, eastward to Russia (about longitude 51°E), yet is absent from Iberia, southern France and northern parts of Fennoscandia and Russia (Juškaitis 2014). It is also absent from eastern Ukraine and southern Russia. Besides mainland Great Britain, island populations also occur on the Isle of Wight in the English Channel, Corfu and Sicily in the Mediterranean Sea and the Baltic islands of Fyn, Zealand, Langeland and Rügen (Juškaitis 2014). It has been recorded up to 1900 m in the Tatra Mountains (Andĕra 1987), 1,920 m in the Austrian Alps (Spitzenberger 2001), 1,980 m in Macedonia (Kryštufek and Petkowski 1990) and 2,032 m in the Italian Alps (Bertolino et al. 2016).

Outside of Europe, this species also occurs in Anatolia.

Population densities and trends vary in different parts of the range, and with habitat type and quality. In Britain, densities average at 2.2 animals per hectare (Bright et al. 2006) but can reach up to 15 animals per hectare in optimal habitat (Bright and Morris 1990). In Sicily, density per hectare proved to be higher in mixed deciduous woodland than in hazel grove (8.2 versus 4.6 adults) (Sara et al. 2001). A study in Switzerland also highlight that estimated densities can vary with survey technique; 2.4 and 6.6 animals per hectare were recorded via nest box checks and traps, respectively (Vogel et al. 2012). On the northern edge of the distribution range (Sweden, Lithuania, Russia), average densities of 1 adult/ha are recorded (Likhachev 1954, Berglund and Persson 2012, Juškaitis 2014).

In some parts of its range, particularly along the northern and north-western limits of its distribution, this species is considered to be in decline. A systematic analysis of dormouse counts from 400 sites in England and Wales indicated a decline of 72% between 1993-2014 (Goodwin et al. 2017), or 48% over the decade leading to 2014 (Mathews and Harrower 2020). Records are scarce or sporadic in Belarus (20 since 2000) (Kachanovskii et al. 2015) but this may be because targeted research on this species is lacking there. Records are also scarce in central and north-western Poland (Atlas Ssakóv Polski 2018), north-eastern Latvia and Estonia where, in the latter, it may now be extinct (Pilats et al. 2022). It is rare in Germany (Meinig et al. 2020), has a small, declining population in Switzerland (Capt et al. 2022), and is of conservation concern in some regions of France (MNHN and OFB 2022). Unfavourable status is also reported in the Netherlands, Hungary, Croatia, Belgium (see https://nature-art17.eionet.europa.eu/article17/). Conversely, the Hazel Dormouse is considered relatively abundant in Lithuania and southern Sweden, and in central and southern parts of its range, its population is thought to be stable (Juškaitis 2018).

The Hazel Dormouse is primarily a woodland species, inhabiting deciduous and mixed deciduous-coniferous forests, forest edges, secondary growth, coppices, and other wooded areas with a dense shrubby understorey. Throughout its distributional range, it prefers the early successional stages of woody vegetation. Hedgerows are important habitat for this species. It is also found in some unusual habitats such as pure beech or spruce forests, roadside plantings, heathland and culm grasses (Büchner and Lang 2014, Juškaitis 2014, Gubert 2022, Phillips et al. 2022). It is an arboreal feeder, foraging on flowers, insects, soft and hard mast (Juškaitis 2014). It produces one to two litters per year with an average of four young per litter (Morris 2004). It tends to avoid movements on open ground (Bright and Morris 1996), but dispersing juveniles have been recorded crossing treeless areas up to 500 m (Büchner 2008). It hibernates overwinter (outside of its Mediterranean range) within ground-level nests (Gubert 2022).

Threats to this species include the loss and fragmentation of habitat combined with changes in woodland management practices, including the reduction in the practice of coppicing, and replacement with uniform homogenously-aged plantations (Juškaitis 2014). The evidence from the National Dormouse Monitoring Programme in the UK also points to a decline in habitat quality. The conservation status of the hazel dormouse may benefit from reinstatement or increased frequency of management practices that maintain successional and diverse habitats within woodland (Goodwin et al. 2018, Wembridge et al. 2019). Climate change factors such as warmer and wetter winters negatively affects hazel dormouse survival (Goodwin et al. 2018, Combe et al. 2022).

The species is used at the local level as a pet or display animal.

It is listed on Appendix III of the Bern Convention, Annex IV of the EU Habitats and Species Directive. At a national scale, hazel dormice are also protected under UK law by the Conservation of Habitats and Species Regulations (2017) and by the Wildlife and Countryside Act (1981) (Philips et al. 2022). In many European countries, this species is included on national Red Lists (e.g. Belarus, Denmark, Estonia, Germany, Great Britain, Latvia, Hungary) (see Juškaitis 2014). This species could benefit from habitat protection and reintroductions, as well as further research into population trends.