No impact of cyantraniliprole on the hibernation success of bumble bees (Bombus terrestris audax) in a soil-mediated laboratory exposure study.

Increasing evidence shows that wild bees, including bumble bees, are in decline due to a range of stressors, including pesticides. Our knowledge of pesticide impacts has consequently grown to enable the design of increasingly realistic risk assessment methods. However, one area where knowledge gaps may still hinder our ability to assess the full range of bee-pesticide interactions is the field of exposure. Exposure has historically been linked to either direct contact with pesticides or the ingestion of contaminated pollen and nectar by bees. However, bumble bees, and other wild bees, may also be exposed to pesticides while using contaminated soil as an overwintering substrate. Yet knowledge of how soil-mediated exposure affects bumble bee health is lacking. Here we take one of the first steps towards addressing this knowledge gap by designing a method for testing the effects of soil-mediated pesticide exposure on bumble bee queen hibernation success. We measured hibernation survival, body weight change and abdominal fat content and found that none of these responses were affected by a field realistic soil exposure to the novel insecticide cyantraniliprole. Our study may help in developing a standardised method to test the effects of the soil-mediated pesticide exposure route in bumble bee queens.

Recovery of the hibernating cavernosum by penile revascularization.

Objective: Chronic ischemia-related cavernous dysfunction is considered irreversible. However, in certain patients, cavernous function appears to recover with penile revascularization. In this study, we investigated a potential cavernous dysfunction reversibility from a clinical perspective. Patients and Methods: We involved 93 young patients in the study with arterial erectile dysfunction (ED) (median age: 30 years). Erectile function tests were performed according to the standard operating procedures of the International Society of Sexual Medicine. Among the participants, 63 and 30 displayed pure arteriogenic and mixed vasculogenic (due to both arterial insufficiency and cavernous dysfunction) ED, respectively. Penile revascularization was performed by anastomosing the inferior epigastric artery to the dorsal artery. The ED treatment success was considered from a score of at least 24 on the International Index of Erectile Function-6. Results: Our results proved that penile revascularization cured 92.1% and 73.8% of the patients with pure arteriogenic and mixed vasculogenic ED, respectively (Kaplan-Meier method, log-rank test: no significant difference). The required time for curing 50% of the patients was 10.5 and 10.0 months for pure arteriogenic and mixed vasculogenic ED, respectively, indicating no recovery delay in patients with mixed vascular ED. Furthermore, the cavernous dysfunction degree did not influence cavernous function recovery. Conclusion: Penile revascularization cured ED in 73.8% of the patients with mixed vasculogenic ED. Cavernous dysfunction appears to be reversible in certain cases. Furthermore, we observed no delay in functional recovery compared to participants with healthy cavernous function. These two discoveries suggest that cavernous function recovery after penile revascularization is similar to the concept of hibernating myocardium in ischemic myocardium. Although cavernous dysfunction is considered irreversible, it could be reversed in multiple cases with blood flow restoration to the cavernous tissue.

Phosphorylated Tau at T181 accumulates in the serum of hibernating Syrian hamsters and rapidly disappears after arousal.

The search for biomarkers for the early diagnosis of neurodegenerative diseases is a growing area. Numerous investigations are exploring minimally invasive and cost-effective biomarkers, with the detection of phosphorylated Tau (pTau) protein emerging as one of the most promising fields. pTau is the main component of the paired helical filaments found in the brains of Alzheimer's disease cases and serves as a precursor in the formation of neurofibrillary tangles (NFTs). Recent research has revealed that analysis of p-Tau181, p-Tau217 and p-Tau231 in blood may be an option for detecting the preclinical stage of Alzheimer's disease. In this study, we have analyzed the values of pTau 181 in the serum of Syrian hamsters during hibernation. Naturally, over the course of hibernation, these animals exhibit a reversible accumulation of pTau in the brain tissue, which rapidly disappears upon awakening. A biosensing system based on the interferometric optical detection method was used to measure the concentration of pTau181 protein in serum samples from Syrian hamsters. This method eliminates the matrix effect and amplifies the signal obtained by using silicon dioxide nanoparticles (SiO2 NPs) biofunctionalized with the αpTau181 antibody. Our results indicate a substantial increase in the serum concentration of pTau in threonine-181 during hibernation, which disappears completely 2-3 h after awakening. Investigating the mechanism by which pTau protein appears in the blood non-pathologically may enhance current diagnostic techniques. Furthermore, since this process is reversible, and no tangles are detected in the brains of hibernating hamsters, additional analysis may contribute to the discovery of improved biomarkers. Additionally, exploring drugs targeting pTau to prevent the formation of tangles or studying the outcomes of any pTau-targeted treatment could be valuable.

Transient Cooling Resets Circadian Rhythms of Locomotor Activity in Lizards.

Animals frequently experience temperature fluctuations in their natural life cycle, including periods of low temperatures below their activity range. For example, poikilothermic animals are known to enter a hibernation-like state called brumation during transient cooling. However, the knowledge regarding the physiological responses of brumation is limited. Specifically, the impact of exposure to low-temperature conditions outside the range of temperature compensation on the subsequent circadian behavioral rhythms remains unclear. In this study, we investigated the effects of transient cooling on the behavioral circadian rhythm in the non-avian reptile, the bearded dragon (Pogona vitticeps). Under constant light (LL) conditions at 30 °C, the animals exhibited a free-running rhythm, and exposure to low temperatures (4 °C) caused a complete cessation of locomotion. Furthermore, we revealed that the behavioral rhythm after rewarming is determined not by the circadian phase at the onset or the duration of cooling, but by the timing of cooling cessation.

Microclimatic drivers of winter bat activity in coast redwood forests.

Bats are among the least well-known mammals, particularly in terms of their behavior and activity patterns during the winter. Here, we use passive acoustic monitoring to overcome some of the challenges inherent in surveying cryptic forest bats during the wet season to quantify overwintering behavior for 11 species in California coast redwood forests under varying microclimates. Because different species are active at different forest heights, we also examined the effect of acoustic detector placement (treetop or ground level). Generalized linear mixed models were used to relate acoustic detection probability for 8 species to daytime and nighttime temperature, relative humidity, water vapor pressure, and detector placement. The results indicate that daytime maximum temperature best explained variation in nightly probability of detection, and temperature threshold at which bats were predicted to be detected varied considerably across species. By using more precise species detection methods, we were able to resolve significant differences in activity patterns between Myotis yumanensis and M. californicus, 2 species with similar acoustic signatures that are often lumped together. Myotis californicus was predicted to have a 50% probability of detection at maximum daytime temperature as low as 12.5 °C, whereas M. yumanensis was not predicted to have 50% detection probability until maximum daytime temperature was at least 22 °C, suggesting that M. californicus spends less time in torpor. Also, monitoring at the top of the canopy revealed 4 migratory species to be present in the ecosystem on significantly more monitoring nights than could be observed using conventional ground-based monitoring methods. Improving winter bat survey methods provides evidence that diverse bat species are more active in redwood forests during the winter than previously documented. This finding suggests that coastal forests could provide important winter bat habitat for both resident and migratory species.

Road mortality of water snakes in light of landscape structure and traffic intensity in north-eastern Hungary.

Road mortality can be a serious threat to different animals, including snakes. However, mortality patterns can vary between species, intraspecific groups, locations and time. We compared the number of road-killed individuals (carcasses) of two semiaquatic water snakes (Natrix natrix and N. tessellata) on 58 km of road sections bordered by an active floodplain and a flood-protected former floodplain on one side and mountainous areas on the other in NE Hungary based on surveys conducted once every two weeks in three non-consecutive years. The results showed high road mortality of snakes, with a spring and an autumn peak corresponding to the times when snakes emerge from and return to hibernating sites. The results show that small-scale spatial differences in road mortality were mediated by landscape structure along the road, while the effects of traffic volume, flood regime and the age and sex of the individuals were negligible. For conservation, the study suggests that establishing culvert passages under the road and/or artificial hibernating sites on the floodplain-side of the roads in critical sections can be promising in reducing road-related mortality.

Microbial urea-nitrogen recycling in arctic ground squirrels: the effect of ambient temperature of hibernation.

Energy conservation associated with hibernation is maximized at the intersection of low body temperature (Tb), long torpor bouts, and few interbout arousals. In the arctic ground squirrel (Urocitellus parryii), energy conservation during hibernation is best achieved at ambient temperatures (Ta) around 0 °C; however, they spend the majority of hibernation at considerably lower Ta. Because arctic ground squirrels switch to mixed fuel metabolism, including protein catabolism, at extreme low Ta of hibernation, we sought to investigate how microbial urea-nitrogen recycling is used under different thermal conditions. Injecting squirrels with isotopically labeled urea (13C/15N) during hibernation at Ta's of - 16 °C and 2 °C and while active and euthermic allowed us to assess the ureolytic activity of gut microbes and the amount of liberated nitrogen incorporated into tissues. We found greater incorporation of microbially-liberated nitrogen into tissues of hibernating squirrels. Although ureolytic activity appears higher in euthermic squirrels, liberated nitrogen likely makes up a smaller percentage of the available nitrogen pool in active, fed animals. Because non-lipid fuel is a limiting factor for torpor at lower Ta in this species, we hypothesized there would be greater incorporation of liberated nitrogen in animals hibernating at - 16 °C. However, we found higher microbial-ureolytic activity and incorporation of microbially-liberated nitrogen, particularly in the liver, in squirrels hibernating at 2 °C. Likely this is because squirrels hibernating at 2 °C had higher Tb and longer interbout arousals, a combination of factors creating more favorable conditions for gut microbes to thrive and maintain greater activity while giving the host more time to absorb microbial metabolites.

The effect of temperature and breathing pattern on the surface activity of ground squirrel pulmonary surfactant.

This study investigates how hibernation affects the surface activity of pulmonary surfactant with respect to temperature and breathing pattern. Surfactant was isolated from a hibernating species, the 13-lined ground squirrel, and a homeotherm, the rabbit, and analysed for biophysical properties on a constrained sessile drop surfactometer. The results showed that surfactant from ground squirrels reduced surface tension better at low temperatures, including when mimicking episodic breathing, as compared with rabbit surfactant. In addition, low temperature adaptation was also observed using only the hydrophobic components of surfactant from ground squirrels. Overall, the data support the conclusion that ground squirrel surfactant has adapted to maintain surface activity during low temperature episodic breathing patterns, and that temperature adaptation is maintained with the hydrophobic components of the surfactant.

The interaction between gut microbiota and hibernation in mammals.

Hibernation, an evolved survival trait among animals, enables them to endure frigid temperatures and food scarcity during the winter months, and it is a widespread phenomenon observed in mammals. The gut microbiota, a crucial component of animal nutrition and health, exhibits particularly dynamic interactions in hibernating mammals. This manuscript comprehensively evaluates the impacts of fasting, hypothermia, and hypometabolism on the gut microbiota of hibernating mammals. It suggests that alterations in the gut microbiota may contribute significantly to the maintenance of energy metabolism and intestinal immune function during hibernation, mediated by their metabolites. By delving into these intricacies, we can gain a deeper understanding of how hibernating mammals adapt to their environments and the consequences of dietary modifications on the symbiotic relationship between the gut microbiota and the host. Additionally, this knowledge can inform our comprehension of the protective mechanisms underlying long-term fasting in non-hibernating species, including humans, providing valuable insights into nutritional strategies and health maintenance.

O-GlcNAcylation of SERCA protects skeletal muscle in hibernating Spermophilus dauricus from disuse atrophy.

Long-term inactivity of skeletal muscle results in muscular disuse atrophy; however, hibernating animals do not experience muscular disuse atrophy during the hibernation period. The molecular mechanism underlining the anti-atrophy effect in these animals is unclear. O-linked N acetyl-ß-D-glucosaminylation (O-GlcNAcylation) and its effect on cell signaling pathways are important mechanisms underlying muscular disuse atrophy; thus, in this study, we investigated O-GlcNAcylation changes during hibernation in Spermophilus dauricus to explore the role of O-GlcNAcylation in the muscle disuse atrophy resistance of hibernating animals. The results showed that during hibernation, the muscle fiber cross-sectional area and ratio of muscle fiber did not change, and the morphological structure of the muscle remained intact, with normal contractile function. The level of O-GlcNAcylation decreased during hibernation, but quickly returned to normal in the periodic arousal stage. The O-GlcNAcylation level of sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (SERCA1) decreased, whereas its activity increased. The decrease in O-GlcNAcylation of SERCA could result in the decreased binding of phospholamban to SERCA1, thus decreasing its inhibition to SERCA1 activity. This in turn can inhibit muscle cell calcium overload, maintain muscle cell calcium homeostasis, and stabilize the calpain proteolytic pathway, ultimately inhibiting skeletal muscle atrophy. Our results demonstrate that periodic arousal along with returning O-GlcNAcylation level to normal are important mechanisms in preventing disuse atrophy of skeletal muscle during hibernation.

IGF-1 and myostatin-mediated co-regulation in skeletal muscle and bone of Daurian ground squirrels (Spermophilus dauricus) during different hibernation stages.

Muscle and bone are cooperatively preserved in Daurian ground squirrels (Spermophilus dauricus) during hibernation. As such, we hypothesized that IGF-1 and myostatin may contribute to musculoskeletal maintenance during this period. Thus, we systematically assessed changes in the protein expression levels of IGF-1 and myostatin, as well as their corresponding downstream targets, in the vastus medialis (VM) muscle and femur in Daurian ground squirrels during different stages. Group differences were determined using one-way analysis of variance (ANOVA). Results indicated that the co-localization levels of IGF-1 and its receptor (IGF-1R) increased by 50% during the pre-hibernation period (PRE) and by 35% during re-entry into torpor (RET) compared to the summer active period (SA). The phosphorylation level of FOXO1 in the VM muscle increased by 50% in the torpor (TOR) group and by 82% in the inter-bout arousal (IBA) group compared to the PRE group. The phosphorylation level of SGK-1 increased by 54% in the IBA group and by 62% in the RET group compared to the SA group. In contrast, the protein expression of IGF-1 and phosphorylation levels of PI3K, Akt, mTOR, and GSK3ß in the VM muscle showed no obvious differences among the different groups. ß-catenin protein expression was up-regulated by 84% in the RET group compared to the SA group, while the content of IGF-1 protein, correlation coefficients of IGF-1 and IGF-1R, and phosphorylation levels of PI3K, Akt, and GSK3ß in the femur showed no significant differences among groups. Regarding myostatin and its downstream targets, myostatin protein expression decreased by 70% in the RET group compared to the SA group, whereas ActRIIB protein expression and Smad2/3 phosphorylation in the VM muscle showed no obvious differences among groups. Furthermore, Smad2/3 phosphorylation decreased by 58% in the TOR group and 53% in the RET group compared to the SA group, whereas ActRIIB protein expression in the femur showed no obvious differences among groups. Overall, the observed changes in IGF-1 and myostatin expression and their downstream targets may be involved in musculoskeletal preservation during hibernation in Daurian ground squirrels.

Paternal behavior in captive fat-tailed dwarf lemurs (Cheirogaleus medius) is preserved under socially relevant conditions.

Fat-tailed dwarf lemurs (Cheirogaleus medius), primates endemic to Madagascar, are obligate hibernators that form stable, lifelong pairs in the wild. Given the temporal constraints imposed by seasonal hibernation, infant dwarf lemurs must grow, develop, and wean within the first two months of life. Maternal as well as paternal infant care, observed in the wild, has been deemed critical for infant survival. Given the importance of fathers' involvement in early infant care, we expect this behavior to persist even under captive conditions. At the Duke Lemur Center, in Durham NC, we observed two families of fat-tailed dwarf lemurs and focused on the behavior of adult males within the first two months of the infants' lives. We report evidence of paternal involvement, including babysitting, co-feeding, grooming, accompanying, and leading infants, consistent with observations from the wild. As expected, paternal babysitting decreased as infants gained independence, while co-feeding increased. Supplemental anecdotes, video recorded by observers, also highlight clear cases of involvement by both parents, and even older siblings, in safeguarding and socializing new infants. We argue that maintaining captive fat-tailed dwarf lemur populations under socially and ecologically relevant conditions facilitates the full expression of physiological and behavioral repertoires. Most importantly, it also allows dwarf lemurs to realize their species' potential and become robust proxies of their wild kin.

Strategies of invasive snail Pomacea canaliculata during hibernation in rice fields of south China: effects of body size, sex, and soil depth.

BACKGROUND: The invasive freshwater snail Pomacea canaliculata is an agricultural pest with a certain level of tolerance to abiotic stress. After the harvest of late rice, the snails usually burrow themselves into the soil surface layers to overwinter and pose a renewed threat to rice production in the following year. Revealing the response of snails to environmental stresses is crucial for developing countermeasures to control their damage and spread. RESULTS: In this study, we conducted a 120-day in situ experiment during the winter to investigate the survival and physiological changes of hibernating snails in 0-5 and 5-10 cm soil depths, aiming to explore their overwintering strategies. Our results showed that 73.61%, 87.50%, and 90.28% of male, female, and juvenile snails survived after hibernation for 120 days in 0-10 cm soil depth, respectively. The differences in survival rates based on sex and size of snails potentially reflect the countermeasures of snails to rapidly reproduce after hibernation. Simultaneously, the hibernating snails exhibited the ability to maintain a certain level of body weight. During this period, the snails increased their antioxidant enzyme activities to cope with oxidative stress, and enhanced their lipid storage. The hibernation survival of snails was not significantly affected by different soil depths, indicating that they have the potential to hibernate into deeper soils. Furthermore, snails were capable of increasing their contents of bound water and glycerol to cope with sudden cold spells during hibernation. CONCLUSION: Our findings emphasize the adaptive changes of P. canaliculata snails overwintering in paddy soils. In future studies, the vulnerabilities of P. canaliculata during hibernation (e.g. shell characteristics, nutrient reserves, and dehydration tolerance, etc.,) should be investigated to develop effective control methods for this period. © 2024 Society of Chemical Industry.

Regulation of mitochondrial metabolism by hibernating bear serum: Insights into seasonal metabolic adaptations.

Hibernating animals undergo a unique and reversible decrease in their whole-body metabolism, which is often accompanied by a suppression of mitochondrial respiration. However, the precise mechanisms underlying these seasonal shifts in mitochondrial metabolism remain unclear. In this study, the effect of the serum from active and hibernating Japanese black bears on mitochondrial respiration was assessed. Stromal-vascular cells were obtained from bear white adipose tissue and cultured with or without an adipocyte differentiation cocktail. When the oxygen consumption was measured in the presence of bear serum, the hibernating bear serum reduced maximal respiration by 15.5 % (p < 0.05) and spare respiratory capacity by 46.0 % (p < 0.01) in the differentiated adipocytes in comparison to the active bear serum. Similar reductions of 23.4 % (p = 0.06) and 40.6 % (p < 0.05) respectively were observed in undifferentiated cells, indicating the effect is cell type-independent. Blue native PAGE analysis revealed that hibernating bear serum suppressed cellular metabolism independently of the assembly of mitochondrial respiratory chain complexes. RNA-seq analysis identified 1094 differentially expressed genes (fold change>1.5, FDR<0.05) related to insulin signaling and glucose metabolism pathways. These findings suggest that the rapid alterations in mitochondrial metabolism during hibernation are likely induced by a combination of reduced insulin signaling and suppressed mitochondrial function, rather than changes in respiratory complex assembly.

Hibernating ribosomes as drug targets?

When ribosome-targeting antibiotics attack actively growing bacteria, they occupy ribosomal active centers, causing the ribosomes to stall or make errors that either halt cellular growth or cause bacterial death. However, emerging research indicates that bacterial ribosomes spend a considerable amount of time in an inactive state known as ribosome hibernation, in which they dissociate from their substrates and bind to specialized proteins called ribosome hibernation factors. Since 60% of microbial biomass exists in a dormant state at any given time, these hibernation factors are likely the most common partners of ribosomes in bacterial cells. Furthermore, some hibernation factors occupy ribosomal drug-binding sites - leading to the question of how ribosome hibernation influences antibiotic efficacy, and vice versa. In this review, we summarize the current state of knowledge on physical and functional interactions between hibernation factors and ribosome-targeting antibiotics and explore the possibility of using antibiotics to target not only active but also hibernating ribosomes. Because ribosome hibernation empowers bacteria to withstand harsh conditions such as starvation, stress, and host immunity, this line of research holds promise for medicine, agriculture, and biotechnology: by learning to regulate ribosome hibernation, we could enhance our capacity to manage the survival of microorganisms in dormancy.

The reduction in relative brain size in the domesticated dog is not an evolutionary singularity among the canids.

Domestication has long been considered the most powerful evolutionary engine behind dramatic reductions in brain size in several taxa, and the dog (Canis familiaris) is considered as a typical example that shows a substantial decrease in brain size relative to its ancestor, the grey wolf (Canis lupus). However, to make the case for exceptional evolution of reduced brain size under domestication requires an interspecific approach in a phylogenetic context that can quantify the extent by which domestication reduces brain size in comparison to closely related non-domesticated species responding to different selection factors in the wild. Here, we used a phylogenetic method to identify evolutionary singularities to test if the domesticated dog stands out in terms of relative brain size from other species of canids. We found that the dog does not present unambiguous signature of evolutionary singularity with regard to its small brain size, as the results were sensitive to the considerations about the ancestral trait values upon domestication. However, we obtained strong evidence for the hibernating common raccoon dog (Nyctereutes procyonoides) being an evolutionary outlier for its brain size. Therefore, domestication is not necessarily an exceptional case concerning evolutionary reductions in brain size in an interspecific perspective.

High levels of mitochondrial dynamics, autophagy, and apoptosis contribute to stable testicular status in hibernating Daurian ground squirrels.

Daurian ground squirrels (Spermophilus dauricus) experience various stress states during winter hibernation, but the impact on testicular function remains unclear. This study focused on the effects of changes in testicular autophagy, apoptosis, and mitochondrial homeostasis signaling pathways at various stages on the testes of Daurian ground squirrels. Results indicated that: (1) During winter hibernation, there was a significant increase in seminiferous tubule diameter and seminiferous epithelium thickness compared to summer. Spermatogonia number and testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were higher during inter-bout arousal, suggesting that the testes remained stable during hibernation. (2) An increased number of mitochondria with intact morphology were observed during hibernation, indicating that mitochondrial homeostasis may contribute to testicular stability. (3) DNA fragmentation was evident in the testes during the hibernation and inter-bout arousal stages, with the highest level of caspase3 enzyme activity detected during inter-bout arousal, together with elevated levels of Bax/Bcl-2 and Lc3 II/Lc3 I, indicating an up-regulation of apoptosis and autophagy signaling pathways during hibernation. (4) The abundance of DRP1, MFF, OPA1, and MFN2 proteins was increased, suggesting an up-regulation of mitochondrial dynamics-related pathways. Overall, testicular autophagy, apoptosis, and mitochondrial homeostasis-related signaling pathways were notably active in the extreme winter environment. The well-maintained mitochondrial morphology may favor the production of reproductive hormones and support stable testicular morphology.

The West African lungfish secretes a living cocoon during aestivation with uncertain antimicrobial function.

One of the most exceptional adaptations to extreme drought is found in the sister group to tetrapods, the lungfishes (Dipnoi), which can aestivate inside a mucus cocoon for multiple years at reduced metabolic rates with complete cessation of ingestion and excretion. However, the function of the cocoon tissue is not fully understood. Here we developed a new more natural laboratory protocol for inducing aestivation in the West African lungfish, Protopterus annectens, and investigated the structure and function of the cocoon. We used electron microscopy and imaging of live tissue-stains to confirm that the inner and outer layers of the paper-thin cocoon are composed primarily of living cells. However, we also repeatedly observed extensive bacterial and fungal growth covering the cocoon and found no evidence of anti-microbial activity in vitro against E. coli for the cocoon tissue in this species. This classroom discovery-based research, performed during a course-based undergraduate research experience course (CURE), provides a robust laboratory protocol for investigating aestivation and calls into the question the function of this bizarre vertebrate adaptation.

Hibernacula of bats in Mexico, the southernmost records of hibernation in North America.

Although Mexico holds the southernmost hibernating bats in North America, information on winter behavior and hibernacula microclimate use of temperate Mexican bats is limited. We studied hibernating bats at high altitudes (>1,000 m a.s.l.) in northern and central Mexico during 5 consecutive winters. Our aims were to document and describe the hibernacula, winter behavior (such as abundance and roost pattern), and microclimates (estimated as adjacent substrate temperature) of cave-hibernating bats in Mexico. We found 78 hibernacula and 6,089 torpid bats of 10 vespertilionid species, increasing by over 50% the number of cave-hibernating bat species and quadrupling the number of hibernacula for Mexico. Hibernacula were at altitudes between 1,049 and 3,633 m a.s.l., located in 3 mountain ranges, mainly in oak and conifer forests. Myotis velifer was the most common species, followed by Corynorhinus townsendii and C. mexicanus. We recorded the adjacent substrate temperatures from 9 species totaling 1,106 torpid bats and found differences in microclimate use among the 3 most common species. In general, abundance of torpid bats in our region of study was similar to those in the western United States, with aggregations of tens to a few hundred individuals per cave, and was lower than in the eastern United States where a cave may hold thousands of individuals. Knowledge of bat hibernation is crucial for developing conservation and management strategies on current conditions while accommodating environmental changes and other threats such as emerging diseases.

Aunque México tiene los murciélagos hibernantes más sureños en Norteamérica, la información sobre el comportamiento invernal y el uso de microclimas en los refugios de hibernación de los murciélagos templados mexicanos es limitada. Estudiamos a los murciélagos hibernantes en altitudes altas (>1000 msnm) en el norte y centro de México durante cinco inviernos consecutivos. Nuestros objetivos fueron documentar y describir las cuevas de hibernación, el comportamiento invernal (como la abundancia y patrón de percha), y el uso de microclimas (estimado como la temperatura del sustrato adyacente), de los murciélagos que hibernan en cuevas en México. Encontramos 78 cuevas de hibernación con 6089 murciélagos en torpor de 10 especies de vespertiliónidos, incrementando en más del 50% el número de especies de murciélagos que hibernan en cuevas y cuadriplicando el número de cuevas de hibernación para México. Las cuevas de hibernación estuvieron en elevaciones entre 1049 y 3633 msnm, localizadas en tres cadenas montañosas, principalmente en bosques de encinos y coníferas. Myotis velifer fue la especie más común, seguida por Corynorhinus townsendii y C. mexicanus. Reportamos las temperaturas del sustrato adyacente de 1106 murciélagos en torpor de nueve especies y encontramos diferencias en el uso de microclimas entre las tres especies más comunes. Aquí proveemos información relevante para especies de murciélagos templados en la ocurrencia más sureña de hibernación de murciélagos en Norteamérica. En general, la abundancia de murciélagos en torpor que encontramos fue similar a las del oeste de Estados Unidos, con agregaciones de decenas y algunos cientos de individuos por cueva; y fue menor que las del este de Estados Unidos, donde las cuevas pueden albergar miles de murciélagos. El conocimiento de la hibernación de murciélagos es crucial para el desarrollo de estrategias de conservación y manejo adecuadas en la actualidad y mientras se adaptan a los cambios ambientales y a otras amenazas tales como las enfermedades emergentes.