Voluntary recording scheme reveals ongoing decline in the United Kingdom hazel dormouse Muscardinus avellanarius population

Prevalence and Molecular Analysis of Encephalomyocarditis Virus-2 in the Hazel Dormouse

The hazel dormouse (Muscardinus avellanarius) population in the UK continues to decline due to habitat loss, despite reintroductions of captive-bred individuals being conducted nationally for over 30 years. Disease surveillance of captive-bred and wild dormice is performed to identify novel and existing disease threats which could impact populations. In this study, we firstly investigated cause of death in seven hazel dormice found dead in England, through next-generation sequencing identifying a virus closely related to a wood mouse encephalomyocarditis virus-2 (EMCV-2). Subsequently, lung tissue samples from 35 out of 44 hazel dormice tested positive for EMCV-2 RNA using a reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and Sanger sequencing methods developed in this study. Formalin-fixed tissues available for nine hazel dormice which tested positive for EMCV-2 RNA were examined microscopically. Three cases showed moderate interstitial pneumonia with minimal to mild lymphoplasmacytic myocarditis, but no evidence of encephalitis. However, the presence of possible alternative causes of death in these cases means that the lesions cannot be definitively attributed to EMCV-2. Here, we report the first detection of EMCV-2 in hazel dormice and conclude that EMCV-2 is likely to be endemic in the hazel dormouse population in England and may be associated with clinical disease.

Selection of Nest Material and Summer Nest Location by the Hazel Dormouse (Muscardinus avellanarius) in the Bidstrup Forests, Denmark

Hazel dormice (Muscardinus avellanarius) construct summer nests for resting and breeding. The nests are built directly in the vegetation, in tree hollows, or in nest boxes. The availability of nest materials and vegetation coverage may affect the likelihood of finding hazel dormice at a location. The aim of the study is: (1) To investigate the preferences of hazel dormice for nesting materials today compared to four decades ago. (2) To investigate hazel dormice preferences for vegetation coverage at nest sites. In total, 148 hazel dormouse summer nests from the Bidstrup forests in Zealand (Denmark), were analysed. Of these, 82 were collected in the period A: 1980−1985 and 66 were collected in B: 2019−2020. In total 26 different nest materials were found. Beech was the major nest material in both periods, and Jacob’s selectivity index indicates that beech is selected for as nesting material and that hazel dormice may travel to collect beech leaves. Nests from period A contained more beech (W = 1521, p < 0.05) and less oak (W = 1304, p < 0.01) compared to nests from period B. Vegetation analysis showed that coverage of shrubs higher than 2 m above ground (W = 1.5, p = 0.07) may be of great importance for hazel dormice.

Structural re-design of the Animex Wildlife Bridge for the Hazel Dormouse (Muscardinus avellanarius): lessons learnt from two connectivity mitigation case studies in the UK

The Hazel Dormouse (Muscardinus avellanarius) is an arboreal mammal present in Europe and Asia minor. The population is declining in the United Kingdom (UK), partially due to habitat fragmentation caused by the development of linear infrastructure such as roads, railways and pipelines. In 2016, we designed and tested an arboreal bridge in Britain that was proven to be effective for Hazel Dormice. Subsequently, the bridge materials were upgraded to meet the technical standards of UK road agencies, so that it could be approved and implemented as mitigation on projects throughout the UK. In the UK, each bridge must be certified for technical approval by the relevant road authority and as the bridge is a unique structure, this can pose challenges on projects. The national safety standards of UK roads would not allow common methods used for arboreal bridges across the world to be applied, so we needed specialised engineering and design adaptations to be implemented. Two overarching installation designs were created: the standalone bridge and the retrofit bridge. Several bridges have now been installed across roads in the UK and we will be discussing the development and implementation process from two case studies: i) a 40-metre retrofit bridge to an underpass in St Athan, Wales and, ii) two 76+ metre bridges retrofit to an overbridge and underpass on the M1 motorway in Gayhurst, Buckinghamshire. The St Athan project was quickly approved and easily installed while the M1 project required several alterations to the design and installation methods to meet specific project requirements. This paper discusses what we have learned from these projects, how these projects have influenced the future designs of the Animex wildlife bridge and how this could be applied to future arboreal wildlife connectivity bridges across the world.

Why link diverse citizen science surveys? Widespread arboreal habits of a terrestrial amphibian revealed by mammalian tree surveys in Britain

Terrestrial anurans, with their typically short limbs, heavy-set bodies and absent claws or toe pads are incongruous tree climbers, but even occasional arboreal locomotion could offer substantial advantages for evading predators or accessing new shelter or food resources. Despite recent interest, arboreal behaviour remains rarely and unsystematically described for terrestrial amphibians in Europe, likely due to fundamental differences in survey methods and therefore a lack of field data. However, other taxa surveys specifically target trees and tree cavities. We undertook collaborations and large-scale data searches with two major citizen science projects surveying for arboreal mammals in Britain to investigate potential tree climbing by amphibians at a national scale. Remarkably, we found widespread arboreal usage by amphibians in England and Wales, with occupancy of hazel dormouse (Muscardinus avellenarius) nest boxes, tree cavities investigated as potential bat roosts and even a bird nest, by common toads (Bufo bufo), but few additional records of frogs or newts. Of the 277–400 sites surveyed annually for dormice since 2009 at least 18 sites had amphibians recorded in nest boxes while of the 1388 trees surveyed for bats a total 1.4% (19 trees) had toads present. Common toads were found using cavities in seven tree species and especially goat willow (Salix caprea). Toads are potentially attracted to tree cavities and arboreal nests because they provide safe and damp microenvironments which can support an abundance of invertebrate prey but the importance of such tree microhabitats for toad conservation remains unknown and our results should be interpreted cautiously. We encourage expanding and linking of unrelated biodiversity monitoring surveys and citizen science initiatives as valuable tools for investigating ecological traits and interactions.

Genotyping-by-sequencing based SNP discovery in a non-model rodent, the endangered hazel dormouse

The hazel dormouse Muscardinus avellanarius presents an exemplary non-model species that is both locally threatened and whose genetic status is not fully understood owing to insufficient resolution of the currently available molecular tools. We performed normalized Genotyping-by-Sequencing (nGBS) on 48 hazel dormouse samples collected across the species European distribution, aiming at discovering useful single nucleotide polymorphism (SNP) markers for the assessment of population structure and genomic diversity. The analyses of > 24,000 SNPs showed a high divergence between the Eastern and Western lineage of the species with high rates of SNP allele fixation, consistent with previous studies suggesting the divergence of lineages occurred over 2 mya. These results indicate that investigating inter-lineage as well as within-lineage genetic composition will be a conclusive approach for identifying conservation strategies in the future. Results presented here indicate the highest genetic divergence in the Italian and Lithuanian populations. We document how nGBS allows the discovery of SNPs that can characterize patterns of genetic variation at multiple spatial scales in a non-model organism. We document how nGBS allows the discovery of SNPs that can characterize patterns of genetic variation at multiple spatial scales in a non-model organism, potentially informing monitoring and conservation strategies.

Earth Observation for Monitoring, Reporting, and Verification within Environmental Land Management Policy

The main aim of the new agricultural scheme, Environmental Land Management, in England is to reward landowners based on their provision of ‘public goods’ while achieving the goals of the 25 Year Environment Plan and commitment to net zero emission by 2050. Earth Observation (EO) satellites appear to offer an unprecedented opportunity in the process of monitoring, reporting, and verification (MRV) of this scheme. In this study, we worked with ecologists to determine the habitat–species relationships for five wildlife species in the Surrey Hills ‘Area of Outstanding Natural Beauty’ (AONB), and this information was used to examine the extent to which EO satellite imagery, particularly very high resolution (VHR) imagery, could be used for habitat assessment, via visual interpretation and automated methods. We show that EO satellite products at 10 m resolution and other geospatial datasets enabled the identification and location of broadly suitable habitat for these species and the use of VHR imagery (at 1–4 m spatial resolution) allowed valuable insights for remote assessment of habitat qualities and quantity. Hence, at a fine scale, we obtained additional habitats such as scrub, hedges, field margins, woodland and tree characteristics, and agricultural practices that offer an effective source of information for sustainable land management. The opportunities and limitations of this study are discussed, and we conclude that there is considerable scope for it to offer valuable information for land management decision-making and as support and evidence for MRV for incentive schemes.