Recent research has found that, among some mammal species, differences in environmental conditions among populations of the same species drive changes in infant and juvenile mortality, but not in the rate of senescence, also known as the rate of ageing. Although this pattern has been confirmed in primates and some carnivores, it remains untested on other taxonomic groups with faster life histories, such as rodents. Here, we analysed age-specific survival in Hazel Dormouse, using a 24-year capture-mark-recapture data set from Lithuania. We used Bayesian survival trajectory analysis (BaSTA) and tested different models of age-specific mortality. The population has experienced three distinct demographic phases-increasing (1999-2006), declining (2007-2014) and stable-low abundance (2015-2022). We divided the dataset into these three periods to assess changes in survival over time. During all three periods, the life expectancy of males was larger than that of females, contrary to the general mammalian trend of higher female survival. Differences in survival among the three periods were primarily due to changes in age-independent mortality and ageing rates, but not due to changes in juvenile mortality. Our findings support the notion that the low variance rate of ageing is limited to species with slow life histories. However, they also suggest that rodents, even those like the Hazel Dormouse which can reduce exposure to external threats, can substantially modulate their ageing rates in response to environmental variation.

Across its entire range, hazel dormouse (Muscardinus avellanarius) populations are increasingly showing signs of decline. In addition, due to insufficient long-term capture-mark-recapture studies, little is known about hazel dormouse population dynamics, making it difficult to target specific conservation measures. In this study, we used long-term capture-mark-recapture techniques to identify demographic patterns of the hazel dormouse population over a period of 40 years and with 26 years of continuous monitoring. By fitting Hidden Markov Models to the annual population growth rates, we identified four distinct periods of population development, including decline, increase, stable high and stable low abundance. Each period lasted from five to eight years and varied in their demographic characteristics. In particular, the number of overwintered females appeared to shape the population dynamics. Our study shows how the hazel dormouse population declines from maximum spring population density at 1.4 individuals per hectare during stable high abundance period to minimum 0.4 individuals per hectare at stable low abundance period and stabilizes at low level for several years without disappearing. Further studies are needed to investigate which extrinsic and intrinsic factors drive changes in population development.

This study monitored a local population of the forest dormouse (Dryomys nitedula), a component of its metapopulation, in Lithuania from 1999 to 2020, marking the north-western edge of its distribution. Regular monitoring of 70 nestboxes spaced in a 50 m grid in an area of 13.5 ha was carried out during 2001–2020 following a pilot study in 1999–2000. A total of 125 individuals were marked with aluminium rings, with their age and sex recorded. Bayesian modelling of survival probabilities revealed that the population, typically comprising 4–8 adult individuals annually, exhibited sex-specific survival rates that significantly influenced population dynamics. Population size was driven by the numbers of adult females in spring, which depended on their winter survival. The gradual decline and eventual extinction of this population over six years were primarily influenced by the disappearance of local males, coupled with insufficient and delayed male immigration from neighbouring populations. This scarcity of male arrivals may reflect broader challenges within the metapopulation, potentially driven by habitat evolution towards mature forest stages and the impacts of forest management practices. Forest dormice were not recorded in other parts of the same forest despite targeted searches using nestboxes at the study’s end, suggesting significant challenges for recolonization within the metapopulation. The study underscores the critical need for conservation strategies that consider habitat quality, connectivity, and gender-specific survival dynamics to mitigate extinction risk in forest dormouse populations.

The edible dormouse Glis glis is known to emit typical calls during the night. These calls were used in various studies for the detection of species presence or habitat occupancy as well as for quantifying abundance estimates. However, to date, we lack rigorous data on the quantification of the call activity throughout the night and within-season changes in calling activity. To fill this gap, we compared the calling activity of the edible dormouse in core and peripheral populations using voice recorders. During the summer when dormice are active, we deployed voice recorders at three sites with high dormice densities in the Czech Republic and three localities with low densities in Lithuania. We found that calling activity during night varied considerably but seasonally it peaked in August. It was lower in July and lowest in September. Rainy or windy nights significantly reduced call frequencies. Edible dormice started calling around sunset and the intensity increased within two hours, with a peak 4-6 hours after sunset. The frequency of calling decreased before sunrise. Call frequencies per hour were slightly lower in Lithuania. The duration of calls ranged from 1 to 1147 seconds and was significantly shorter at the Lithuanian sites. Our study shows that edible dormice call at a high rate even in peripheral populations and offers promising support for biodiversity surveys and acoustic monitoring.

A melanistic forest dormouse Dryomys nitedula was recorded among 125 individuals marked in a small isolated local population in central Lithuania. Until now, a totally black individual of D. nitedula was captured only in western Ukraine. A review of the literature on colour anomalies in European dormouse species has shown that this phenomenon is rare in dormice. Several black hazel dormice Muscardinus avellanarius were recorded in the same locality in northern Germany in 1972 and 2015, and one such dormouse was captured in the UK. Partial albino M. avellanarius was recorded in Germany. Two melanistic garden dormice Eliomys quercinus were collected in the Czech Republic, an albino specimen in France and a flavistic specimen in Germany. In the edible dormouse Glis glis, melanistic, albino, isabelline and flavistic individuals were recorded, all from Slovenia and the Czech Republic. Among aberrant-coloured European dormice, melanistic individuals were documented most often. Tail-tip albinism is more frequent among M. avellanarius, and this trait was recorded in several countries.

This study aimed to evaluate the significance of dormice in the diets of predators in Europe and, as a result, expand the knowledge about dormouse ecology. A total of 535 sources containing information on dormice in the diets of predators were analysed. Countries of Southern and Central Europe stand out with the largest numbers of target sources. Dormice were recorded in the diets of 54 predator species: 23 mammals, 11 owls, 16 diurnal birds and 4 reptiles. Owls hunting in forests, particularly the tawny owl Strix aluco, are the main dormouse predators. The role of dormice in the diets of predators depends on dormouse abundance, and the highest proportion was recorded in the Mediterranean region, where edible dormice Glis glis are abundant. In particular periods, dormice may be an alternative prey for owls and some other predators. Dormice were seldom recorded in the winter diets of predators, especially in mammals, contrary to what was previously thought. Records of dormice in the winter diets of owls confirm that dormice leave their hibernacula during arousals in the thaw periods. The presence of dormice in the diets of diurnal birds suggests that nocturnal dormice may also be active in the daytime.

The impact of factors such as density dependence, food availability and weather are known to be important for predicting population change in a wide range of species. However, a challenge in ecology is understanding the contributory and interactive role of these drivers on populations. This is necessary to design effective conservation and management strategies. Using data from long‐term studies of five hazel dormouse Muscardinus avellanarius populations in Europe, we tested the relationship between population density and weather and their impact on demographic rates. We used an integrated population modelling approach, estimating age‐specific overwinter survival, annual population growth and fecundity rates. We found strong negative effects of population density, precipitation and winter temperature on population growth rates. This suggests that warmer and wetter weather negatively affects dormouse survival for both adults and juveniles, but we found subtle differences in these effects between age classes. We also identified an interaction between weather measures and population density on age‐specific survival, possibly as a result of weather impacts during hibernation. Although we found low winter temperature was positively associated with population growth, we found evidence consistent with density dependence. We discuss our results in the context of woodland habitat conservation management.

The phenology of many species shows strong sensitivity to climate change; however, with few large scale intra-specific studies it is unclear how such sensitivity varies over a species' range. We document large intra-specific variation in phenological sensitivity to temperature using laying date information from 67 populations of two co-familial European songbirds, the great tit (Parus major) and blue tit (Cyanistes caeruleus), covering a large part of their breeding range. Populations inhabiting deciduous habitats showed stronger phenological sensitivity than those in evergreen and mixed habitats. However, populations with higher sensitivity tended to have experienced less rapid change in climate over the past decades, such that populations with high phenological sensitivity will not necessarily exhibit the strongest phenological advancement. Our results show that to effectively assess the impact of climate change on phenology across a species' range it will be necessary to account for intra-specific variation in phenological sensitivity, climate change exposure, and the ecological characteristics of a population.

The Forest Dormouse, Dryomys nitedula, has a wide geographic distribution, from Switzerland in the west, through eastern and southern Europe, Asia Minor and the Caucasus, to central Russia, central Asia and Mongolia in the east. Previous phylogenetic studies revealed highly divergent lineages in some part of the distribution, suggesting that the history of the species might be complex and a revision of the taxonomy might be warranted. In order to clarify the status of the subspecies identified in previous studies, we increased the current Genbank dataset (n=106) by analyzing >150 samples from Italy, Hungary, Lithuania, the Czech Republic, Russia, Bulgaria, Romania, Austria, and Greece. Preliminary phylogenetic analyses, based on cytochrome b, show the presence of five super lineages with two highly divergent lineages in Iran and Russia. These preliminary results will be completed by additional samples from Mongolia and Afghanistan. This study should help shed light on the evolutionary history of this species across its distribution.

Identifying the environmental drivers of variation in fitness-related traits is a central objective in ecology and evolutionary biology. Temporal fluctuations of these environmental drivers are often synchronized at large spatial scales. Yet, whether synchronous environmental conditions can generate spatial synchrony in fitness-related trait values (i.e., correlated temporal trait fluctuations across populations) is poorly understood. Using data from long-term monitored populations of blue tits (Cyanistes caeruleus, n = 31), great tits (Parus major, n = 35), and pied flycatchers (Ficedula hypoleuca, n = 20) across Europe, we assessed the influence of two local climatic variables (mean temperature and mean precipitation in February-May) on spatial synchrony in three fitness-related traits: laying date, clutch size, and fledgling number. We found a high degree of spatial synchrony in laying date but a lower degree in clutch size and fledgling number for each species. Temperature strongly influenced spatial synchrony in laying date for resident blue tits and great tits but not for migratory pied flycatchers. This is a relevant finding in the context of environmental impacts on populations because spatial synchrony in fitness-related trait values among populations may influence fluctuations in vital rates or population abundances. If environmentally induced spatial synchrony in fitness-related traits increases the spatial synchrony in vital rates or population abundances, this will ultimately increase the risk of extinction for populations and species. Assessing how environmental conditions influence spatiotemporal variation in trait values improves our mechanistic understanding of environmental impacts on populations.

It is well known that survival and the dynamics of wild populations are affected by environmental factors. Recent research has found that, among some species of mammal, differences in environmental conditions between populations of the same species translate into changes in infant and juvenile mortality, but not in the rate of senescence (‘rate of aging’). This has been confirmed among primates and some species of carnivores, but has not been tested on other taxonomic groups, such as rodents. Here, we analyse age-specific survival and mortality on the most extensive capture-mark-recapture data set on Hazel Dormouse available from Lithuania. We used Bayesian survival trajectory analysis (BaSTA) and tested different models of age-specific mortality. Since the Hazel Dormouse population is in decline across its northern distribution, potentially in response to climate change, we divided the data into three periods to assess changes in survival over time. Regional climate data were obtained from the NOAA data service to test the effect of climatic factors on survival during winter and summer respectively. Our results show that, during all three periods, male life expectancies were longer than those of females. We found that the overall level of mortality was high for all three periods, with lowest mortality during the period 1999 - 2004. We found large differences in juvenile mortality and age-independent mortality between the three periods, but not in adult mortality or in the rate of senescence. This is consistent with previous findings on other mammals, supporting the invariant rate of aging hypothesis.

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.

Aim:Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW). Location:Global. Taxon:All extant mammal species. Methods:Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species). Results:Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use. Main conclusion:Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control.

Dormice are widely distributed through Eurasia and Africa, but their abundance varies considerably. In many regions, dormice are rare, and their role in ecosystems is considered to be unimportant. The aim of this study was to evaluate the significance of dormice in the diet of predators in the Palaearctic (excluding Japan). A total of 540 sources, containing information on dormice in the diet of predators was analysed. Countries of Southern and Central Europe had the largest numbers of target sources. Dormice were recorded in the diet of 57 predator species: 21 mammals, 13 owls, 18 diurnal birds and 5 reptiles. Owls hunting in the forests, particularly the Tawny Owl (Strix aluco), are the main dormouse predators. The highest proportion of dormice in the diet of predators was recorded in the Mediterranean region, where Edible Dormice (Glis glis) are abundant and some other dormouse species are sympatric. In particular periods, dormice may be an alternative prey for predators such as Tawny Owl and even Lynx (Lynx lynx). It was supposed previously that predation was an important cause of high winter mortality in dormice, but analysis of publications showed that dormice were rather seldom recorded in the winter diet of predators. Thus, the exact impact of predators on winter mortality of dormice remains unclear. The role of dormice in the diet of predators depends on dormouse abundance. In areas where dormice are rare, it is trivial. However, predators catching even individual females, may have a significant impact on dormouse reproductive success.

BackgroundThe European Robin (Erithacus rubecula) is eurytopic in its choice of nest site, which can be either half-open or closed, and situated either on the ground or at a height of several meters. On occasion, robins also nest in closed nestboxes, though generally only solitary such cases are documented, albeit that dozens of such events can be recorded during the course of some long-term studies. However, until now, nobody has summarised the peculiarities of robins nesting in closed nestboxes.MethodsIn the period 1978–2020, wooden tit and starling nestboxes were inspected regularly at five study sites in Lithuania, this totaling more than 18, 000 nestbox-seasons. During these inspections, 90 cases of robins nesting in the nestboxes were recorded. Publications on this topic from the entire robin distribution range were reviewed.ResultsRobins prefer to nest in old large-sized fairly shallow nestboxes with wide entrance holes, for example starling nestboxes or tit nestboxes with enlarged entrance holes. Increased numbers of nestboxes being occupied by robins were recorded for 3–8 years in row. In Lithuania, nesting success in nestboxes is not higher than compared with nesting on the ground. Tree climbing mammals, Pine Martens (Martes martes), Hazel Dormice (Muscardinus avellanarius), Edible Dormice (Glis glis) and Forest Dormice (Dryomys nitedula), are the main predators of robin nests in nestboxes.ConclusionsSome geographic variation was found in the occurrence of robins nesting in nestboxes with more such cases recorded in central and southern parts of the range. Possibly robins are more philopatric in these parts of the range, with the same females or their offspring nesting in nestboxes for several years in row. In areas inhabited by dormice, nesting in closed nestboxes is not advantageous for robins.

We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.

The use of artificial nestboxes has improved the understanding of the ecology and behaviour of secondary cavity-nesting animals. Although earlier investigations have shown that nestbox characteristics can influence where animals roost or breed, the impact of ageing of nestboxes on occupation rates has rarely been investigated with experiments based on choice. In this study, the occupation rate of new and old wooden nestboxes set up side by side on the same tree (n = 140 pairs) was investigated in mixed coniferous-deciduous forest in Lithuania. Great tits Parus major and pied flycatchers Ficedula hypoleuca evidently preferred to breed in new nestboxes, while hazel dormice Muscardinus avellanarius and yellow-necked mice Apodemus flavicollis did not show any preference to a certain nestbox type and equally occupied old and new nestboxes. Saxon wasps Dolichovespula saxonica also occupied both nestbox types equally and a similar tendency was observed in European hornets Vespa crabro. By contrast, black garden ants Lasius niger showed a tendency to occupy old nestboxes. The results of the present study are important when considering the use of nestboxes in monitoring small hole-nesting birds and hazel dormice. The preference of birds for new nestboxes may influence long-term monitoring results when nestboxes become older and when old nestboxes are replaced with new ones. This important limitation has not been emphasised in review papers on the inadequacies of nestboxes in studies of hole-nesting birds. However, as ageing of nestboxes does not influence the occupation rates by hazel dormice, the use of nestboxes does not bias the results of long-term monitoring of this species.

The hazel dormouse (Muscardinus avellanarius) is a rare and threatened species in many European countries. However, it is common and widespread in Lithuania where forest management practice, particularly small-scale clear-felling, is considered to be favourable for this species. The long-term study was carried out in regenerating clearing which fell in the area of the dormouse study site. The forest plot was clear-felled in the winter 2001/2002, and regrowth was thinned in 2004, 2007, 2010 and 2014. During 2003–2019, average adult dormouse density in regenerating clearing (1.6 ± 0.7 adults/ha) was significantly higher than average density in the entire area of the study site (1.0 ± 0.3 adults/ha). Clear-felling had only short-term negative effect on dormouse abundance. It increased already in the 3rd year after clear-felling when dormouse density exceeded 2 adults/ha and reached its maximum in the 7th–9th years after clear-felling. Dormouse abundance decreased since the 14th year after clear-felling. Thinning of regrowing woody vegetation had only temporary negative impact on dormouse abundance in the current or next year depending on the timing of thinning in early summer or autumn, respectively. Practice of small-scale clear-felling could be used for the hazel dormouse conservation in countries where this species is endangered.

The dynamics of socio-spatial organisation are little investigated in dormice (Gliridae), a specific group among small mammals. During 2007–2017, 668 adult individuals were captured in a hazel dormouse (Muscardinus avellanarius) population in Lithuania, with the home ranges calculated for 134 males and 62 females. Over the study period, the abundance of the population gradually declined, and it was categorised into three groups: (1) high (1.2–1.4 adults/ha), (2) medium (0.9–1.0 adults/ha) and (3) low (0.4–0.7 adults/ha). When population abundance changed from high to low, the average sizes of home ranges increased from 1.4 ± 0.6 to 2.1 ± 1.2 ha in males and from 0.8 ± 0.5 to 1.1 ± 0.4 ha in females, while the total overlap of home ranges decreased from 57 ± 28 to 35 ± 23% in males and from 77 ± 27 to 44 ± 32% in females. Home ranges of marked individuals changed in consecutive years. In males, the average displacement of the centres of the home ranges was 58 ± 21 m, 75 ± 52 m and 73 ± 39 m at high, medium and low densities, respectively. The dynamics of the spatial relations in the investigated hazel dormouse population are consistent with the general tendency of home ranges to increase when population density decreases. However, the spatial organisation of population is more stable and potentially less related to the dynamics of food resources in comparison with other forest-dwelling small mammals.