Eliomys Quercinus Research Articles

Do We Look for the Right Ones? An Overview of Research Priorities and Conservation Status of Dormice (Gliridae) in Central Europe

There are differences regarding distribution, conservation status and protection according to national and European laws and directives between the four dormouse species (Gliridae) native to Central Europe. We question the coherence between scientific knowledge and conservation status of dormice in Europe and hypothesize that the species included in the Habitats Directive have been the subject of considerable research, while those not included have been neglected, despite having an unfavourable conservation status. We did a review of the research presented at the International Conferences on Dormice from 1990–2017 and published in the scientific literature since 1950 to see for which species the most research was done and whether the Habitats Directive had an impact. The number of presentations increased over time for the Hazel (Muscardinus avellanarius, N = 200) and the Edible dormouse (Glis glis, N = 150), while those on the Garden dormouse (Eliomys quercinus, N = 46) decreased until 2014 with an apparent increase only in 2017; the Forest dormouse (Dryomys nitedula, N = 67) does not show any trends. The number of published articles increased for all species except for the Garden dormouse. This focus does not adequately address the current threats of the species. The results can serve as a guide for the re-evaluation of future research priorities and conservation strategies as well as the implementation of new monitoring projects and ecological studies.

Sticking Together: Energetic Consequences of Huddling Behavior in Hibernating Juvenile Garden Dormice.

AbstractHibernation, or multiday torpor, allows individuals to save energy via substantial reductions of metabolism and body temperature but is regularly interrupted by euthermic phases called arousals. Social thermoregulation, or "huddling," can act in synergy with torpor in reducing individuals' energy and heat losses. In the wild, the garden dormouse (Eliomys quercinus) combines both strategies, which are crucial for winter survival of juveniles with limited prehibernation body fat reserves. We investigated via thermographic and temperature measurements (i) the energetic impact of huddling during an arousal from deep torpor, (ii) the dynamics of huddling behavior during hibernation, and (iii) its consequences during the entire winter in juvenile garden dormice. Thermographic images revealed a significant effect of huddling on torpor energetics, as it reduced heat exchange and mass loss by two-thirds in huddling versus single individuals during arousal. Our investigation of the dynamics of huddling further revealed a "random-like mechanistic" behavior during winter hibernation, as arousals from torpor were not always initiated by the same individuals. Animals took turns in initiating rewarming within a group, and the individual with highest body temperature during arousal entered into torpor later than the others within the huddle. The animals share both costs and benefits of huddling during arousals, without any energetic benefit of huddling over the entire winter on an individual level. We conclude that the dynamics of social thermoregulation during hibernation seems to counterbalance its benefit of reducing energetic costs associated against the energy-demanding process of rewarming from torpor.

A large-scale citizen science approach to assess the distribution and ecology of the declining Garden Dormouse in Germany

The Garden Dormouse has shown an ongoing decline over the last decades across large parts of its range. As the reasons for the species’ shrinking range are poorly understood, effective conservation actions have been lacking so far. The Germany- wide project “In Search of the Garden Dormouse” aims to investigate the causes, and develop concepts and measures to mitigate the decline. The current distribution has been assessed using a large-scale citizen science approach. More than 6,000 dormouse observations were gathered via an online reporting tool, of which >4,000 reports could be verified by photos, videos, or call recordings. Our aim was to obtain important information about the ecology of the species in different habitat types. For this, volunteers systematically collected approximately 1,000 Garden Dormouse droppings for food analysis, installed footprint tunnels and camera traps, helped to obtain several hundred DNA samples, collected > 500 carcasses, and recorded Garden Dormouse calls from various sampling sites. Volunteers also used a novel device for automated Garden Dormouse monitoring in the field that was developed and successfully applied in support of the project. The gathered data displays the current Garden Dormouse distribution in Germany and provides insights into the biology and ecology of this endangered, understudied species. The multidisciplinary approach of the project combined several disciplines, from field ecology to population genomics, in a fruitful cooperation of scientists, citizen scientists, and a conservation NGO. It can serve as a template for future projects aiming to produce large-scale scientific data in animal research and conservation.

Places to be: the Garden Dormouse (Eliomys quercinus) in south-western Germany

In Germany the Garden Dormouse (Eliomys quercinus) is assumed to have one of its main distributional areas in the south-western federal state of Baden-Württemberg. However, recent and detailed information from this area was lacking. In order to describe the actual distribution of the Garden Dormouse, and to characterize suitable habitats in this region, a monitoring study was conducted within the national biodiversity project “In Search of the Garden Dormouse” in 2021. Footprint tunnels and wildlife cameras were used to systematically investigate the occurrence of the species on 136 plots distributed over Baden-Württemberg. The data set was combined with Garden Dormouse records from a citizen science online reporting tool, registered between 2019 and 2021. The Garden Dormouse was found most frequently in the mountainous, conifer-rich Black Forest and in the settlements of the Mannheim-Heidelberg region. Another type of habitat was the dry deciduous forests bordering the river Rhine in the Southern Upper Rhine Valley. Only two isolated occurrences were detected in the eastern part of Baden-Württemberg. The results of this study show, that the distribution of the Garden Dormouse in South-West Germany is more limited than previously assumed. However, the diversity of the detected habitats is considerable, ranging from coniferous forests in higher altitudes to urban areas and almost sub-mediterranean deciduous forests. Further studies will focus on the ecology and biology of this species in the latter. For Germany this is an exceptional, but also threatened, habitat which may serve as a stepping stone to recolonize suitable forest habitats in the Rhine valley.

Perpetuating ambiguity: a review of Garden Dormouse (Eliomys quercinus) records from Romania

Published records of species are often uncritically cited by other authors. However, when such records are based on uncertain data, reproducing them can misrepresent species distribution or conservation status. This, in turn, may result in misguided management decisions for threatened taxa. While still widely distributed in southwestern Europe, eastern populations of the Garden Dormouse (Eliomys quercinus) are small and isolated, and the species has seen a serious decline in recent decades. Given the patchy nature of this eastern range, as well as a general confusion regarding its Romanian presence, our study aimed at critically reviewing all Garden Dormouse records from this country. The mammal collections of several Romanian museums were inspected for Garden Dormouse specimens, and literature data were reviewed to assess the validity of records. Aspects such as presence of voucher specimens, photographic or biometric evidence, type of record, ecological or behavioural data were considered when analysing published records. Eleven museum specimens and 31 literature records of alleged E. quercinus were identified. All museum specimens were re-determined as being forest dormice (Dryomys nitedula). None of the publications provided either photos, measurements or detailed description of individuals, which might have excluded confusion with the Forest Dormouse. Another peculiar aspect was the frequent lack of Forest Dormouse records, even in regions where the species is presently known to occur. In conclusion, our study failed to detect unambiguous evidence of past or present Garden Dormouse occurrence in Romania, which raises new questions about the range and status of this species.

Historical distribution of the Garden Dormouse in Poland

The Garden Dormouse (Eliomys quercinus), is the rarest species of the Gliridae family in Central Europe. So far, information on the occurrence of this species in Poland is based mainly on historical data in the literature. The presence of the Garden Dormouse is additionally confused by the occurrence of the Forest Dormouse (Dryomys nitedula) of similar appearance. The range of both species overlap in Poland, and they have often been distinguished incorrectly. The aim of the research was to critically analyse the known localities of the Garden Dormouse in Poland, using both literature data and museum collections. The analysis of museum collections indicated errors in species identification, where specimens of the Forest Dormouse were usually described as a Garden Dormouse. New, previously unknown, localities have also been found. Most numerous in the collections are specimens from the vicinity of Babia Góra (Western Carpathians), where 5 individuals were caught in the early 1960s. Another occurrence of the Garden Dormouse in the Carpathians was recorded in Zakopane in the second half of the 19th century. Another region of the species’ occurrence is the area of Lusatia, in the lowland, western part of the country, where one specimen was found. The last specimen was found in Silesia in the first half of the 20th century. The remaining literature information should be considered uncertain. The last certain information about the occurrence of the Garden Dormouse in Poland comes from the 1960s from Zawoja (vicinity of Babia Góra) and since then, despite intensive searches in the 1970s and 1980s, this species has not been found in the localities where it was captured earlier. There have been significant changes in the landscape in the areas where the species historically occurred. The mosaic of mountain pastures, arable fields and small spruce forests, constituting a favourable habitat for the Garden Dormouse, has been replaced by beech forests, which are currently dominated by the Edible Dormouse (Glis glis).

Combining citizen science and conservation genomics to reveal the causes of rapid population decline in the Garden Dormouse (Eliomys quercinus)

The Garden Dormouse (Eliomys quercinus) is a native European rodent species that has suffered extensive range contraction and severe population decline across large parts of its distribution in Central and Eastern Europe and is now considered extinct in several countries. At the same time, contrasting population dynamics are observed in its western distribution, where Garden Dormice are regionally abundant and even occupy habitats in the built environment. Reasons for these opposing range dynamics and drastic declines remain unknown. We therefore started a long-term cooperation project, joining the efforts of different research institutions, conservation NGOs and citizen scientists to investigate the underlying causes. Here, we present the results of a RADseq analysis of 103 samples collected from several parts of the European species range to infer regional phylogeography and delineate different conservation units. Preliminary genomic data show the existence of highly divergent genetic lineages, even on a local scale. Based on these findings, we have developed a reduced SNP panel, which allows for lineage discrimination, assessment of population structure and identification of individuals from non-invasively collected samples. The panel is now routinely applied in Garden Dormouse conservation, e.g., when selecting appropriate locations to release displaced Garden Dormice found accidentally or to identify isolated Garden Dormouse populations in need of improved habitat connectivity.

Dormice (Mammalia, Gliridae) in Ukraine: сurrent state of knowledge and perspectives of investigations

I am setting up the national databases for four species of the Gliridae family (Dryomys nitedula, Glis glis, Muscardinus avellanarius, Eliomys quercinus) with data available from museum collections, scientific literature, biodiversity social networks, and original observations in nature made within the borders of Ukraine. The database contains 656 records: Dryomys nitedula 287 records, Glis glis 152 records, Muscardinus avellanarius 216 records and Eliomys quercinus 1 record. Dryomys nitedula is listed in the Red Lists of 5 administrative regions, Glis glis in the Red Lists of 2 administrative regions, and Muscardinus avellanarius in the Red Lists of 4 administrative regions. We revealed 2 findings of Glis glis outside the known range of this species. The current state of knowledge and distribution of Gliridae representatives in Ukraine are discussed. We propose to change the conservation status of the Garden Dormouse Eliomys quercinus, which is listed in the Red Data Book of Ukraine (2009) as a critically endangered species (a species on the edge of extinction). The revision of literature and museum samples attributed to this species has demonstrated that the only specimen, that without a doubt belongs to this species, collected in the Cherkasy region in 1965, was assigned to a non-existent settlement. The rest of the museum specimens (one from Ivan Franko National University of Lviv Zoological Museum and one from the National Museum of Natural History National Academy of Sciences of Ukraine) were redefined as Dryomys nitedula.

The gastrointestinal tract histology of Eliomys quercinus and Glis glis

The Garden Dormouse (Eliomys quercinus) and the Edible Dormouse (Glis glis) differ in their omnivorous diet, with the first being more carnivorous and readily consuming small vertebrates and even poisonous invertebrates, while the latter consumes more plant-based foods. These differences could lead to histological differences in their gastrointestinal tract, which we wanted to test. Six animals of each species were caught in nature and fed the same diet for two weeks to diminish the impact of the short-term external factors. Tissue samples were taken of middle oesophagus, glandular stomach, middle small intestines and large intestines. They were stained with H&E for measuring the thickness of layers in oesophagus gastric mucosa and epithelial cell height in the intestines. Alcian blue - PAS stain was used for goblet cell count and type identification in the intestines, differentiating blue (acidic), lilac (neutral) and purple (mixed) cells. Results showed Eliomys quercinus having greater variance in oesophageal layer thicknesses, significantly thicker muscularis mucosae and thinner tunica muscularis in the oesophagus, and thicker gastric mucosa compared to Glis glis. Eliomys quercinus also had a significantly higher total goblet cell count in both intestines and a higher count of each type in the large intestine, although Glis glis had far more mixed and neutral goblet cells in the small intestine. Both showed intriguingly low numbers of neutral goblet cells in the small intestine. These results indicate interesting differences in gastrointestinal histology and goblet cell distribution in comparison with their distinct diets.

Diel activity patterns of Garden Dormice (Eliomys quercinus) assessed by camera trap data

Garden Dormouse populations have been decreasing in range and declining in number throughout Europe. Understanding, and therefore preventing, this decline is urgently needed. To devise effective conservation strategies, it is essential to gain knowledge on activity patterns of the target species. Diel activity patterns of Garden Dormice (Eliomys quercinus) were investigated at 25 different sites in Germany. Through an intensive camera-trap survey from March to October 2020 a total of 192,136 pictures were recorded in over 3,682 camera-trap days. The association between activity and environmental parameters, such as habitat (urban vs. natural), the lunar phase and sunrise and sunset, was investigated. Garden Dormice were found to be predominantly nocturnal, but were occasionally active during the day in the summer months. The peak of activity at all sites was shortly before midnight. Garden Dormice in this study did not arrange their activity according to the lunar phase. Daytime activities could be related to the presence of young or the food supply. Weather conditions and cloud cover could explain the small influence of the lunar phase on the animals’ activity. This study revealed the effectiveness of camera trapping to gather information on activity of an elusive small rodent with minimum disturbance to the animals. The data was useful for analyzing and understanding diel activities in different habitats.

Distribution data of the dormice species in Romania: a review

All four species of dormice present in Romania are listed as Vulnerable in the Romanian Red Book of Vertebrates and are protected by national laws. Even though they are important bioindicators of the condition of forest habitats, little is known about their distribution. We reviewed the distribution data for the Romanian dormice species: the Garden Dormouse (Eliomys quercinus), Hazel Dormouse (Muscardinus avellanarius), Edible Dormouse (Glis glis), and Forest Dormouse (Dryomys nitedula). Our sources include published scientific literature, online databases (such as GBIF, Observation.org and iNaturalist), museum collections, verified citizen’s data as well as original data. A database was organized in GeoPackage format in QGIS 3.16.0. Historical locations from old scientific papers were georeferenced and included in the database with all metadata found. Recent and original data locations were recorded using geographical coordinates. Our aim was to produce up to date distribution maps for the dormice species occuring in Romania that can be further used in potential habitat modelling for the study and protection of these species and their habitat. We found the most abundant observation were of Muscardinus avellanarius and the least recorded species was Eliomys quercinus, without any recent data.

Was everything better in the good old days? Declining body mass in the Garden Dormouse (Eliomys quercinus)

Garden Dormouse (Eliomys quercinus) populations have shown a drastic decline over the last 20-30 years, the reasons for this decline are still unknown. In wild animals, body mass is a good indicator of fitness and survival probability, especially in hibernating species like dormice. Fat accumulation before the onset of hibernation and juvenile growth are crucial to survive the following winter. We conducted a capture-mark-recapture study in the Black Forest (south-western Germany) between 2018 and 2021 and compared the body mass of captured Garden Dormice with data collected between 2003 and 2005. Furthermore, we investigated the dietary spectrum of this species by faecal analyses. The results show that adult Garden Dormice nowadays have a significantly lower body mass (difference 11 ± 2.8 g) before the onset of hibernation than two decades ago. Furthermore, juveniles showed a significantly lower body mass gain in the years 2018-2021 compared to juveniles in 2003-2005. Dietary analyses have revealed that insects represent the main food resource for juvenile Garden Dormice and also in adults during pre-hibernation fattening. This study shows, that the body mass of the Garden Dormice in the Black Forest has decreased over the last two decades, which could reduce their reproductive success and their survival rate, especially during hibernation. A reason for this body mass reduction could be the severe decline of insects leading to an insufficient availability of the key food resource of this species. In particular, reproductive females might not be able to cover their investment during gestation and lactation.

The masked singer: vocalization in the Garden Dormouse (Eliomys quercinus)

Many animals make sounds for various reasons, mostly for mating and agonistic behaviour, but also for more complex social communication. These sounds are used for mapping and monitoring many animal groups and species (e.g. birds, bats, whales, grasshoppers, crickets) for mapping and monitoring. Although Glirids are known to use sounds for communication, to our knowledge vocalisations have only been used to map the Edible Dormouse. We checked the possibility of detecting the Garden Dormouse calls and used oscillograms and spectrograms to analyze these sounds. Garden Dormouse calls were recorded as mp4 files and converted to WAV format for this purpose. In combination with video recordings, the vocalisations could often be associated with the respective behaviour of the animals. Most analysed calls were related to apparent arousal, intraspecific aggression, mating or social communication within a family group between old and young animals. Some of the different calls are not yet clearly understood in their ethological context. Regardless of this, Garden Dormouse vocalizations can be clearly assigned to the species and distinguished from other species. It therefore provides a new method for mapping this species. When Garden Dormice mainly call in urban habitats, human impacts like habitat fragmentation, direct disturbance or noise pollution may challenge their acoustic behaviour in this environment.

You are what you eat: on the diet of the Garden Dormouse

The Garden Dormouse is considered the most carnivorous species among Glirids. However, this information is based on small sample sizes. In order to develop conservation measures for this declining species, understanding its feeding ecology is crucial. In this context, we studied the diet of the Garden Dormouse in Germany using microscopic analyses of 1,000 faeces collected in different habitats over 3 years. We also examined 100 stomachs from fresh carcasses. More than 90 % of all faeces contained food of animal origin, mainly arthropods, also annelids and molluscs, but rarely vertebrates. It was possible to identify most food items of animal origin to Order level, in some cases even the species was determined. Almost all faecal samples contained plant material, mainly vegetative parts of plants (74.5 %) but also generative parts (25.5 %). Fruits like raspberries, blueberries or blackberries play a role as food sources in late summer. Surprisingly, seeds are of secondary importance. Results from stomach analysis show a higher proportion of annelids and molluscs, but otherwise confirm the data from faecal samples. Our results confirm that the Garden Dormouse is a generalist omnivore. It preys on a wide range of animals of different taxonomic groups, also many different plant species and parts. Due to the high proportion of food of animal origin, Garden Dormice are on a higher trophic level compared to other European dormouse species. They are, therefore, vulnerable to losses of arthropod biomass and sensitive to pesticide accumulation.

Distribution of Glirids in an Alpine national park

In this long-term study, we evaluated the distribution of three species of Glirids: Hazel Dormouse (Muscardinus avellanarius), Garden Dormouse (Eliomys quercinus) and Edible Dormouse (Glis glis) in the Gran Paradiso National Park (Western Italian Alps). The aim was to investigate the ecology, adaptation strategies, and distribution of these dormouse populations along an altitudinal gradient. Monitoring started in 2015 and is still ongoing. We used five different techniques (searching for nests, grids of nest boxes, transects of live traps, nesting tubes, and footprint tunnels), placed along an altitudinal gradient from 700 to 2300 m a.s.l. We found a total of 680 signs of the presence of Hazel Dormouse and 46 individuals, 275 signs and 142 individuals of the Garden Dormouse and 674 signs and 67 individuals of the Edible Dormouse. The three species selected different altitudinal gradients: Edible Dormouse from 800 to 1700 m, with a prevalence between 800-1100 m; Garden Dormouse from 1100 to 2000 m, with a prevalence between 1400-1700 m. The Hazel Dormouse was ubiquitous from 800 to 2032 m, without a clear altitudinal pattern. Edible Dormice were mainly found in deciduous and mixed forests, while Garden Dormice usually occurred in coniferous forests. The Hazel Dormouse seemed to be regularly distributed in all forest types up to the tree limit. These results, obtained from diverse methodologies, permitted comparison between the monitoring protocols, improved knowledge of habitat selection by Glirids in Alpine habitats, as well as providing novel insights within the context of climate change.

Developing a novel bioacoustic monitoring for Garden Dormice using passive sound recorders and machine learning

One of the challenges of small mammal conservation is to be able to find the target species in the field. This is especially true for small nocturnal hibernators like dormice. Passive bioacoustic monitoring, as a non-invasive method, can be a useful tool to more efficiently find vocalizing animals in the field. However, bioacoustic methods produce a large amount of data, of which the manual analysis is highly time consuming. Therefore, there is need for an automatized process for identifying animal vocalization in acoustic data. Two types of recorders, audiomoths and BAR-LT recorders, were installed at a total of 10 locations of known Garden Dormouse (Eliomys quercinus) activity in Germany and were left recording in the field from June to September, producing a total of 3.54 TB of data. Based on our own and volunteers’ observations, Garden Dormouse vocalizations were manually identified in a subset of the sound files produced. These vocalizations, as well as ambient sound samples, were labelled and extracted to train a TensorFlow model, which was then tested on new subsets of the complete dataset. Comparing sound quality and acquisition costs of the two recorder types shows the potential for large-scale monitoring applications using the less expensive and open source audiomoth. Next steps include a time analysis of Garden Dormouse calls to find out when they are vocally more active during the study period. Such knowledge can help narrow the temporal scale of future bioacoustic studies on this species.

Nest sites used for daytime rest in urban Garden Dormice (Eliomys quercinus) in Wiesbaden, Germany

Garden Dormouse (Eliomys quercinus) populations have declined by 50% throughout Europe over the last 30 years. They are increasingly found in German cities, but little is known about their urban lifestyle. A radiotelemetry study was performed in the city of Wiesbaden, to investigate the daily resting habits of Garden Dormice. The location and structure of nest sites used for daytime rest (DNS) of five individuals (one female, four males) were recorded each to every second day during the months of May to July 2021. The animals were located 90 times in total in a DNS, and two to six different DNS per animal were identified. DNS were found in hedges, trees, bird nests, facade greening, nest boxes, and inside buildings. Garden Dormice in this study were often located in DNS that provide consistent temperatures (false floors, walls) and a high degree of protection from predators. DNS with visual cover and possible food supply (facade greening, hedges) were also often used. The frequency with which DNS were changed varied greatly depending on the individual. The dormice in this study showed adaptations to urban living, as each animal used at least one anthropogenic structure as DNS. Recommended conservation measures for Garden Dormice in urban areas, based on this study, include raising public awareness and protection and promotion of facade greening (climbing plants on walls and fences), hedges and old buildings. Further research on the life of Garden Dormice in urban areas is needed.

The contribution of dormice monitoring to the assessment of the conservation status of species in Latvia in accordance with IUCN criteria

In Latvia, four dormouse species have been recorded. In 2016 an annual monitoring of the Hazel Dormouse (Muscardinus avellanarius) and Forest Dormouse (Dryomys nitedula) was commenced within the national biodiversity monitoring programme to obtain data that would allow assessmen of the conservation status of those species and their habitats. The nestbox method was used for the surveys, as it is equally suitable for collecting data on all four species of dormice. Since 2016, 133 temporary study plots with 5–15 nest-boxes each, were established all over the country to record species presence. Sevenadditional permanent study plots collected data on population dynamics, each consisting of at least 50 nestboxes placed within a grid system at 50 m intervals. No Garden Dormice (Eliomys quercinus) were recorded, supporting the presumption that this species has vanished in Latvia. A new location for Edible Dormouse (Glis glis) has been discovered. The Forest Dormouse is found exclusively in a small area near the Latvia-Belarus border, but Hazel Dormice found in Latvia are probably are part of a metapopulation located to the south. No overlapping of distribution areas of species was found. The previous assessment of dormouse species, according to outdated IUCN criteria, was done 20 years ago. Re-assessment according to current IUCN criteria, and using monitoring data, is now carried out within the recently commenced LIFE FOR SPECIES project (2021–2024). Preliminary assessments indicate that each dormouse species will be classified in different categories - rangingfrom Least Concern to Regionally Extinct.

Status and distribution of dormice (Mammalia, Gliridae) in Bulgaria

Here we summarize all available data about dormice (Gliridae) in Bulgaria, published one and our own observations, collected in the last 20 years. Four species are found in Bulgaria - the Forest Dormouse (Dryomys nitedula), the Edible Dormouse (Glis glis), the Hazel Dormouse (Muscardinus avellanarius) and the Roach’s Mouse-tailed Dormouse (Myomimus roachi). Altogether we collected 1200 records from 283 locations. A database has been created in which every single record is kept. The most common and widespread species are the Edible (G. glis) and Forest Dormouse (D. nitedula), found in 212 and 139 locations respectively. They inhabit mainly the deciduous and mixed forest in the country. The Hazel Dormouse (M. avellanarius) is found in 77 locations, the bulk of them are in the mountains, but there are some locations along the Danube and southeast Bulgaria. It prefers woods with a well-developed understorey. The Roach’s mouse-tailed dormouse (M. roachi) is the rarest one - found in 26 locations in southeast Bulgaria. In contrast to the other dormice, it avoids woods and lives in semi-open habitats with shrubs, tree lines, and islands in grasslands and agricultural fields. There are several anecdotal reports of the Garden Dormouse (Eliomys quercinus) but no hard proof exists for the presence of this species. We discussed the patterns of distribution, conservation status, and coexistence of Bulgarian dormice.

Living in a changing world: Physiological and behavioural flexibility of juvenile Garden Dormice

Heterothermy, or torpor, allows individuals to save energy by active reduction of metabolism and decreased body temperature. Social thermoregulation or huddling allows individuals to minimize energy needs while maintaining a relatively high body temperature. The Garden Dormouse (Eliomys quercinus), a highly endangered European rodent, uses both strategies of torpor and huddling, which are particularly beneficial for young individuals to cope with environmental fluctuations. Since juveniles are an important component of population renewal, determining the flexibility of energy-saving strategies and its consequences on somatic integrity of young individuals is key to protecting this species. We measured individual torpor patterns, body mass gain and structural growth, and assessed telomere dynamics in male and female juvenile Garden Dormice according to housing condition (singly or groups of four individuals) and food availability (fed ad-libitum or energy-limited) before and during hibernation. During development, juveniles used more frequent, longer and deeper torpor when housed singly than in groups. Torpor was encouraged by lower food availability. Juveniles showed similar body mass gain and growth, irrespective of experimental conditions. During hibernation, huddling dormice showed similar hibernating patterns and mass loss compared to single individuals regardless of food availability. Telomere lengthened across all individuals before hibernation, with larger elongation in males, which also experienced greater telomere loss than females during hibernation. We conclude that the use of torpor and huddling allows juvenile Garden Dormice to cope successfully with energetic bottlenecks, without major effects on somatic integrity. Future studies will need to confirm such findings under natural environmental conditions.