Duration Of Hibernation Research Articles

Weather prediction using traditional knowledge in cold arid high altitude region of Ladakh in India

The Union territory of Ladakh in India is a cold arid high altitude region. The subsistence nature of agriculture being practiced (by majority of farmers) in the region is solely dependent on melted glacier water. The present study was undertaken in Leh district of Ladakh to identify, prioritize and understand the traditional knowledge (TK) used by the farming community for prediction of weather. The primary data were collected from 320 households from 20 villages in Leh district from 2015 to 2020. The primary data were aided and validated by Focused Group Discussions with key informants and stakeholders working in the region such as scientists from research institutions and officials from agriculture and line departments. Farmers used combination of indicators including behavioral changes of birds and animals, change in atmospheric events and inferences drawn from Lotho (almanac) to predict weather. Migration pattern of birds was the most ancient, common and widely prevalent TK used for prediction of onset and extent of snowfall and winter season by farmers. Building of nest by birds on poplar tree (Poplus sp.) at different heights and directions was used to predict temperatures in the forthcoming summer season. The duration of hibernation of Himalayan marmots (Marmota himalayana) was an indication of duration of snowfall and winter temperatures. Timing and extent of precipitation (rainfall and snowfall) was used to predict the distribution of snowfall and winter temperatures. Lotho was extensively used for planning agricultural operations till a decade ago. The farming community used different TK in totality to enhance the accuracy of weather prediction. It was found that improved connectivity of the region with the mainland, introduction of modern communication technologies and decreasing dependence on agriculture as a primary livelihood option (because of the emergence of non-farm based opportunities such as services and tourism) have made the use of TK less prevalent among young generation farmers. However, the majority of the farmers expressed the need for blending TK and modern science for addressing location-specific problems.

Why hibernate? Tests of four hypotheses to explain intraspecific variation in hibernation phenology

Abstract Hibernation is a remarkable behaviour deployed by a diverse array of endotherms within many clades that greatly reduces metabolic need, but also has somatic costs. Hibernation in modern endotherms is often assumed to be an adaptation allowing animals to avoid extreme thermal conditions or food shortages in seasonal environments. However, many animals hibernate when foraging conditions are energetically profitable, suggesting other causal factors influence hibernation behaviour. Understanding the selection pressures responsible for intraspecific variation in the timing and duration of hibernation can help elucidate the relative evolutionary influences of the ultimate ecological causes of hibernation. We tested four previously proposed mechanistic hypotheses to explain intraspecific variation in hibernation phenology in the federally threatened northern Idaho ground squirrel (Urocitellus brunneus): (1) thermal tolerance, (2) food limitation, (3) predation avoidance and (4) sexual selection. The predation avoidance and sexual selection hypotheses received the most support, although we also found some support for the thermal tolerance and food limitation hypotheses. Heavy squirrels increased hibernation duration regardless of environmental conditions, as predicted solely by the predation avoidance hypothesis. Reproductive males emerged from hibernation earlier in spring than other sex–age classes, a pattern predicted by the sexual selection hypothesis. Temperature and food availability explained a much smaller amount of the variation in hibernation behaviour, only partially supporting predictions of the thermal tolerance and food limitation hypotheses. Our results indicate that animals navigate life‐history trade‐offs between energetic allocation to survival and reproduction via state‐dependent optimization of hibernation phenology. Consequently, any future environmental changes that influence body condition will have implications for population ecology and life‐history evolution of hibernating animals due to stark differences in daily survival probability between hibernation and the active season. Read the free Plain Language Summary for this article on the Journal blog.

The Mesozoic terminated in boreal spring

The Cretaceous–Palaeogene mass extinction around 66 million years ago was triggered by the Chicxulub asteroid impact on the present-day Yucatán Peninsula1,2. This event caused the highly selective extinction that eliminated about 76% of species3,4, including all non-avian dinosaurs, pterosaurs, ammonites, rudists and most marine reptiles. The timing of the impact and its aftermath have been studied mainly on millennial timescales, leaving the season of the impact unconstrained. Here, by studying fishes that died on the day the Mesozoic era ended, we demonstrate that the impact that caused the Cretaceous–Palaeogene mass extinction took place during boreal spring. Osteohistology together with stable isotope records of exceptionally preserved perichondral and dermal bones in acipenseriform fishes from the Tanis impact-induced seiche deposits5 reveal annual cyclicity across the final years of the Cretaceous period. Annual life cycles, including seasonal timing and duration of reproduction, feeding, hibernation and aestivation, vary strongly across latest Cretaceous biotic clades. We postulate that the timing of the Chicxulub impact in boreal spring and austral autumn was a major influence on selective biotic survival across the Cretaceous–Palaeogene boundary.

Long-term individualized monitoring of sympatric bat species reveals distinct species- and demographic differences in hibernation phenology

BackgroundHibernation allows species to conserve energy and thereby bridge unfavorable environmental conditions. At the same time, hibernation imposes substantial ecological and physiological costs. Understanding how hibernation timing differs within and between species can provide insights into the underlying drivers of this trade-off. However, this requires individualized long-term data that are often unavailable. Here, we used automatic monitoring techniques and a reproducible analysis pipeline to assess the individualized hibernation phenology of two sympatric bat species. Our study is based on data of more than 1100 RFID-tagged Daubenton’s bats (Myotis daubentonii) and Natterer’s bats (Myotis nattereri) collected over seven years at a hibernaculum in Germany. We used linear mixed models to analyze species-, sex- and age-specific differences in entrance, emergence and duration of the longest continuous period spent in the hibernaculum.ResultsOverall, Daubenton’s bats entered the hibernaculum earlier and emerged later than Natterer’s bats, resulting in a nearly twice as long hibernation duration. In both species, adult females entered earlier and emerged from hibernation later than adult males. Hibernation duration was shorter for juveniles than adults with the exception of adult male Natterer’s bats whose hibernation duration was shortest of all classes. Finally, hibernation timing differed among years, but yearly variations in entrance and emergence timing were not equally shifted in both species.ConclusionsOur results suggest that even in sympatric species, and across sex and age classes, hibernation timing may be differentially affected by environmental conditions. This highlights the necessity of using individualized information when studying the impact of changing environments on hibernation phenology.

Survival estimates of free-living arctic ground squirrels (Urocitellus parryii): effects of sex and biologging

Hibernation is associated with long lifespan: on average, hibernating mammals live 15% longer than nonhibernators of equivalent mass. We investigated how survival varies with sex, season, and the deployment of biologgers in arctic ground squirrels (Urocitellus parryii (Richardson, 1825)), a widely distributed northern hibernator. The duration of hibernation in arctic ground squirrels differs markedly by sex: females hibernate 30% longer each year than males, a behavioural trait that could positively affect female survival. Additionally, males engage in aggressive territorial and food cache defense in spring and fall, which may decrease survival in this sex. From 13 years of mark–recapture data, we estimated apparent survival of arctic ground squirrels in Arctic Alaska (USA) using Cormack–Jolly–Seber models in program MARK. We found that females had higher annual survival ([Formula: see text] (95% confidence interval (CI): 0.469, 0.913)) than males ([Formula: see text] (95% CI: 0.416, 0.670)), with a maximum observed lifespan (10 years) that exceeded that of males (6 years). We also show that biologger use and implantation did not significantly impact survival. Quantifying basic arctic ground squirrel demographics from this well-studied population illustrates how sex-specific hibernation parameters may influence lifespan differences in male and female arctic ground squirrels and provides support for the safety of biologging devices.

What is winter? Modeling spatial variation in bat host traits and hibernation and their implications for overwintering energetics.

White‐nose syndrome (WNS) has decimated hibernating bat populations across eastern and central North America for over a decade. Disease severity is driven by the interaction between bat characteristics, the cold‐loving fungal agent, and the hibernation environment. While we further improve hibernation energetics models, we have yet to examine how spatial heterogeneity in host traits is linked to survival in this disease system. Here, we develop predictive spatial models of body mass for the little brown myotis (Myotis lucifugus) and reassess previous definitions of the duration of hibernation of this species. Using data from published literature, public databases, local experts, and our own fieldwork, we fit a series of generalized linear models with hypothesized abiotic drivers to create distribution‐wide predictions of prehibernation body fat and hibernation duration. Our results provide improved estimations of hibernation duration and identify a scaling relationship between body mass and body fat; this relationship allows for the first continuous estimates of prehibernation body mass and fat across the species' distribution. We used these results to inform a hibernation energetic model to create spatially varying fat use estimates for M. lucifugus. These results predict WNS mortality of M. lucifugus populations in western North America may be comparable to the substantial die‐off observed in eastern and central populations.

Retrospective analysis of hibernation parameters and breeding success in captive Vancouver Island marmots (Marmota vancouverensis): 1997-2018.

Vancouver Island marmots (Marmota vancouverensis) have been managed in a captive-breeding program since 1997, as in situ conservation efforts were insufficient in raising the numbers of this critically endangered species. The success of captive-breeding programs centers on sustainable reproduction and survival of individuals once released into the wild. Captive-born Vancouver Island marmots released to the wild have lower survival rates than their wild-born counterparts; this difference may arise from compromised hibernation patterns or behaviors. Hibernation duration, body weight over the hibernation season, and reproductive success of captive Vancouver Island marmots were reviewed to assess the effect of these variables on each other. Data from a total of 1782 hibernations and 456 breeding attempts were compiled from 1997 to 2018. The number of winters spent in captivity, the origin of the marmot (captive-born or wild-born), the facility at which hibernation occurred, and the body weight all had a significant effect on hibernation length (all p < .001). Increased weight was associated with increased hibernation length by 0.4 ± 0.1 day/kg on average (p = .0015). Captive, wild-born marmots hibernated for significantly longer than their captive-born counterparts by about 21 ± 2 days (p < .001). The odds of successful breeding were significantly increased with increasing hibernation length by approximatively 20% for every 10 additional days of hibernation. This study provides information on the intrinsic relationship between body weight, reproduction, and hibernation in captive Vancouver Island marmots.

Post-Natal Movement, Habitat Use, and Hibernacula Selection of Eastern Box Turtles (Terrapene carolina carolina) in Southern New England

Understanding movement patterns of hatchling Terrapene carolina carolina (Eastern Box Turtle) may be critical to guide conservation and management efforts since little is known about this early life-history stage. We used radio-telemetry to track 10 hatchling Eastern Box Turtles from 28 August 2012 to 21 August 2013 in Hamden, CT, to investigate postnatal movement patterns, habitat use, and hibernacula selection. We also report nest characteristics, clutch size, incubation length, hatching success, hibernation length, and overwintering mortality rates. The mean number of eggs laid in each of 5 nests was 5 (min–max = 1–6 eggs). Incubation varied from 83 to 97 days (mean = 90 days), and the overall hatching success rate was 63%. Hatchling movement (n = 6) was directional towards the north-northeast prior to hibernation. The mean distance hatchlings moved per day was 3.8 m. Mean total distance traveled was 131 m and mean straight-line distance from nest to hibernacula was 95 m. Average total distance turtles moved between observations in 2013 was significantly less than 2012 (P = 0.0001). The post-natal period averaged 35 days, with hibernation occurring before 12 October 2012. Hibernacula locations varied between partially canopied sites within the open fields and closed-canopy conditions on the forest/open-field interface. Hibernation duration averaged 177 days, with all juveniles emerging from hibernation before 6 April 2013. Movement patterns ceased to be directional after hibernation, suggesting the initiation of a home range. While dispersing from their nests, hatchlings selected microsites higher in shrub cover, and just before hibernation, microsites with higher sapling and tree cover. Following hibernation, juveniles did not return to pre-hibernation microhabitats, either in the woods or in fields. Following hibernation, juveniles continued to occupy open fields, but occupied microhabitats with partial canopy cover. A strong preference for microhabitats higher in shrub cover did not persist into the second year.

Tissue-specific telomere dynamics in hibernating arctic ground squirrels (Urocitellus parryii).

Hibernation is used by a variety of mammals to survive seasonal periods of resource scarcity. Reactive oxygen species (ROS) released during periodic rewarming throughout hibernation, however, may induce oxidative damage in some tissues. Telomeres, which are the terminal sequences of linear chromosomes, may shorten in the presence of ROS, and thus the telomere length of an individual reflects the degree of accrued oxidative damage. This study quantified telomere length dynamics throughout hibernation in arctic ground squirrels (Urocitellus parryii). We hypothesized that telomere dynamics are tissue specific and predicted that telomere shortening would be most pronounced in brown adipose tissue (BAT), the organ that directly supports non-shivering thermogenesis during arousals. We used qPCR to determine relative telomere length (RTL) in DNA extracted from liver, heart, skeletal muscle (SM) and BAT of 45 juvenile and adult animals sampled either at mid- or late hibernation. Age did not have a significant effect on RTL in any tissue. At mid-hibernation, RTL of juvenile females was longer in BAT and SM than in liver and heart. In juvenile females, RTL in BAT and SM, but not in liver and heart, was shorter at late hibernation than at mid-hibernation. At late hibernation, juvenile males had longer RTL in BAT than did juvenile females, perhaps due to the naturally shorter hibernation duration of male arctic ground squirrels. Finally, BAT RTL at late hibernation negatively correlated with arousal frequency. Overall, our results suggest that, in a hibernating mammal, telomere shortening is tissue specific and that metabolically active tissues might incur higher levels of molecular damage.

Results of percutaneous coronary interventions in patients with dysfunctional myocardium.

Aim: to evaluate immediate and long-term results of endovascular treatment of patients with dysfunctional viable myocardium. Material and methods. 220 patients were included in the study and were divided into 2 groups. The main group (n=138) included patients with proven ischemia and the presence of viable myocardium in the post-MI zone, on account of which they performed endovascular intervention on the arteries that supply the viable myocardium. The control group (n=82) was formed retrospectively and included patients who were on optimal medical therapy, with invasive diagnostics and endovascular treatment not performed by such patients. The viability of the myocardium was determined by the methods ofMRI of the heart with delayed contrast and the method of stress echocardiography with dobutamine. Inclusion criteria: angina pectoris II-IV functional class (CCS); the presence of proven myocardial ischemia according to stress tests; occlusion or subtotal stenosis of one or more coronary arteries according to digital angiography (SYNTAX score &lt;32); presence of segments with disturbed local contractility of left ventricular myocardium; presence of a viable myocardium in the zone of the occluded / stenotic artery; circulatory failure of I-III functional class (NYHA); left ventricular ejection fraction (LVEF) less than 50%. Results. The magnetic resonance imaging (RMI) with delayed contrasting at the preoperative stage allows to reliably estimate the existing violations of local contractility in the zone of the hibernated myocardium, in comparison with the method of stress echocardiography with dobutamine. After 12 and 18 months of follow-up, there was a significant increase in the incidence of non-fatal MI in the control group. In all patients in the long-term period after PCI completion, a significant increase in the left ventricular ejection fraction and an improvement in the local contractility of the myocardium are noted. Among patients who underwent MRI of the heart, it was possible to detect a significant decrease in the mass fraction of ischemic myocardium in the post-MI zone. There was a strong positive correlation (r = 0.54, p&lt;0.05) between the duration of myocardial hibernation and the timing of restoration of its function after PCI. Conclusion. PCI performance in patients with dysfunctional viable myocardium is highly effective, compared with patients receiving only medication. The method of MRI of the heart with delayed contrast allows judging more objectively the dynamics Оригинальные исследования of the restoration of the function of the hibernated viable myocardium and remodeling of the heart after the revascularization, in comparison with stress echocardiography with dobutamine.

Shallow Torpor Expression in Free-Ranging Common Hamsters With and Without Food Supplements

Energy expenditure during winter can be reduced by expressing torpor, which is characterized by decreased metabolic rate and body temperature. In addition to deep, multiday torpor bouts alternating with short arousal episodes during the hibernation period, common hamsters can also enter shallow torpor bouts (STBs), lasting for less than 24 h at a minimum body temperature between 30-20 °C. Food supplements provided shortly before winter have been shown to shorten hibernation in males, but did not affect hibernation duration in females. In the presented study, we analyzed the expression of STBs and compared supplemented to unsupplemented common hamsters. Body temperature during winter was recorded using subcutaneously implanted data loggers (iButtons). The results revealed that supplemented males showed more STBs and thus spent more time in shallow torpor than unsupplemented individuals. The duration of STBs, however, was shorter in supplemented males and both mean and minimum body temperature were significantly higher compared to unsupplemented males. In females, shallow torpor expression did not differ between individuals with and without food supplements. STBs were mainly expressed before the onset of the first deep, multiday torpor bout, but the number of STBs was not related to that of deep torpor bouts. These results indicate that in males, shallow torpor combined with feeding on food stores could be the more appropriate overwintering strategy when sufficient external energy reserves are available. Females generally cache more food than males and are therefore assumed to be less affected by the additional food stores. These results underline the flexibility of the species in the use of heterothermy and could enable adequate and rapid responses to changes in food availability.

Human development and climate affect hibernation in a large carnivore with implications for human–carnivore conflicts

Abstract Expanding human development and climate change are dramatically altering habitat conditions for wildlife. While the initial response of wildlife to changing environmental conditions is typically a shift in behaviour, little is known about the effects of these stressors on hibernation behaviour, an important life‐history trait that can subsequently affect animal physiology, demography, interspecific interactions and human‐wildlife interactions. Given future trajectories of land use and climate change, it is important that wildlife professionals understand how animals that hibernate are adapting to altered landscape conditions so that management activities can be appropriately tailored. We investigated the influence of human development and weather on hibernation in black bears (Ursus americanus), a species of high management concern, whose behaviour is strongly tied to natural food availability, anthropogenic foods around development and variation in annual weather conditions. Using GPS collar data from 131 den events of adult female bears (n = 51), we employed fine‐scale, animal‐specific habitat information to evaluate the relative and cumulative influence of natural food availability, anthropogenic food and weather on the start, duration and end of hibernation. We found that weather and food availability (both natural and human) additively shaped black bear hibernation behaviour. Of the habitat variables we examined, warmer temperatures were most strongly associated with denning chronology, reducing the duration of hibernation and expediting emergence in the spring. Bears appeared to respond to natural and anthropogenic foods similarly, as more natural foods, and greater use of human foods around development, both postponed hibernation in the fall and decreased its duration. Synthesis and applications. Warmer temperatures and use of anthropogenic food subsides additively reduced black bear hibernation, suggesting that future changes in climate and land use may further alter bear behaviour and increase the length of their active season. We speculate that longer active periods for bears will result in subsequent increases in human–bear conflicts and human‐caused bear mortalities. These metrics are commonly used by wildlife agencies to index trends in bear populations, but have the potential to be misleading when bear behaviour dynamically adapts to changing environmental conditions, and should be substituted with reliable demographic methods.

Pesticide reduces bumblebee colony initiation and increases probability of population extinction.

Pollinators are in global decline, and agricultural pesticides are a potential driver of this. Recent studies have suggested that pesticides may significantly impact bumblebee colonies, an important and declining group of pollinators. Here we show that colony founding queens, a critical yet vulnerable stage of the bumblebee lifecycle, are less likely to initiate a colony after exposure to thiamethoxam, a neonicotinoid insecticide. Bombus terrestris queens were exposed to field-relevant levels of thiamethoxam, and two natural stressors, the parasite Crithidia bombi, and varying hibernation durations. Exposure to thiamethoxam produced a 26% reduction in the proportion of queens that laid eggs, and advanced the timing of colony initiation, although we did not detect impacts of any experimental treatment on the ability of queens to produce adult offspring during the 14-week experimental period. As expected from previous studies, hibernation duration also had an impact on egg laying, but there was no significant interaction with insecticide treatment. Modelling the impacts of a 26% reduction in colony founding on population dynamics dramatically increased the likelihood of population extinction. This shows that neonicotinoids can affect this critical stage in the bumblebee lifecycle, and may have significant impacts on population dynamics.

The hibernating mobile phone: Dead storage as a barrier to efficient electronic waste recovery

Hibernation, the dead storage period when a mobile phone is still retained by the user at its end-of-life, is both a common and a significant barrier to the effective flow of time-sensitive stock value within a circular economic model. In this paper we present the findings of a survey of 181 mobile phone owners, aged between 18–25years old, living and studying in the UK, which explored mobile phone ownership, reasons for hibernation, and replacement motives. This paper also outlines and implements a novel mechanism for quantifying the mean hibernation period based on the survey findings. The results show that only 33.70% of previously owned mobile phones were returned back into the system. The average duration of ownership of mobile phones kept and still in hibernation was 4years 11months, with average use and hibernation durations of 1year 11months, and 3years respectively; on average, mobile phones that are kept by the user are hibernated for longer than they are ever actually used as primary devices. The results also indicate that mobile phone replacement is driven primarily by physical (technological, functional and absolute) obsolescence, with economic obsolescence, partly in response to the notion of being ‘due an upgrade’, also featuring significantly. We also identify in this paper the concept of a secondary phone, a recently replaced phone that holds a different function for the user than their primary phone but is still valued and intentionally retained by the user, and which, we conclude, should be accounted for in any reverse logistics strategy.

Thermal climate‐linked variation in annual survival rate of hibernating rodents: shorter winter dormancy and lower survival in warmer climates

Summary In seasonal climates, many animals, including a wide range of small mammals, are physiologically capable of prolonged dormancy (˜hibernation), when foraging‐related activity ceases entirely for part the year. Low metabolic rates while dormant minimise energy and water requirements, but the behavioural state of inactivity also reduces exposure to mortality risks, especially predation. Thermal effects on activity underlie spatial patterns in annual survival rate of ectothermic animals. We hypothesised that, because local thermal conditions affect the duration of mammalian hibernation, positive effects of dormancy on survival could also underlie a negative relationship between spatial variation in thermal climate and annual survival rate among populations of hibernating rodents. We applied mixed models to test for effects of local thermal climate on collated data of hibernation duration and annual survival rate among populations of hibernating and a representative sample of non‐hibernating rodent species. Our analyses revealed strong negative effects of mean annual temperature on hibernation duration and adult annual survival rate within hibernating species (β: −8·6 day and −5·1% per 1 °C) but no effect in non‐hibernating rodent species. This thermal climate‐linked pattern in annual survival rate seems to be unique among mammals. A parsimonious explanation lies in the large increase in monthly survival rates during hibernation compared to activity. The current spatial pattern suggests ongoing climate warming might reduce annual survival rates of hibernating rodents by shortening their hibernation season. Decreased annual survival because of increased activity in warmer climates with shorter winter seasons is an unappreciated mechanism leading to impacts of global warming on animal populations in temperate climates.

How to spend the summer? Free-living dormice (Glis glis) can hibernate for 11 months in non-reproductive years.

Edible dormice are arboreal rodents adapted to yearly fluctuations in seed production of European beech, a major food source for this species. In years of low beech seed abundance, dormice skip reproduction and non-reproductive dormice fed ad libitum in captivity can display summer dormancy in addition to winter hibernation. To test whether summer dormancy, that is, a very early onset of hibernation, actually occurs in free-living dormice, we monitored core body temperature (Tb) over ~12 months in 17 animals during a year of beech seeding failure in the Vienna Woods. We found that 8 out of 17 dormice indeed re-entered hibernation as early as in June/July, with five of them having extreme hibernation durations of 11 months or more (total range: 7.8–11.4 months). Thus, we show for the first time that a free-living mammal relying on natural food resources can continuously hibernate for >11 months. Early onset of hibernation was associated with high body mass in the spring, but the distribution of hibernation onset was bimodal with prolonged hibernation starting either early (prior to July 28) or late (after August 30). This could not be explained by differences in body mass alone. Animals with a late hibernation onset continued to maintain high nocturnal Tb’s throughout summer but used short, shallow torpor bouts (mean duration 7.44 ± 0.9 h), as well as occasional multiday torpor for up to 161 h.Electronic supplementary materialThe online version of this article (doi:10.1007/s00360-015-0929-1) contains supplementary material, which is available to authorized users.

Age and sex differences in hibernation patterns in free-living Anatolian ground squirrels

Anatolian ground squirrels, Spermophilus xanthoprymnus (Bennett, 1835), are nearly endemic to Turkey. Various aspects of the biology of Anatolian ground squirrels have been studied. However, a detailed description of hibernation, with special attention to age and sex differences, has not previously been reported. Thus, in this study, we aimed to present a detailed description of hibernation in a population of free-living Anatolian ground squirrels, with special attention to age and sex differences, in relation to soil temperature (Tsoil) at the expected depth of the hibernacula. This study is the first such study for Old World ground squirrels (the genus Spermophilus sensu stricto) and incorporates an additional species from a different environment (e.g. warmer than those of others) into comparative studies of hibernation patterns in Holarctic ground squirrels (the tribe Marmotini) under natural conditions. Body temperature (Tb) was continuously recorded from late summer to spring by intraperitoneally implanted temperature loggers and Tsoil by a temperature logger at a depth of 1m in the field. Anatolian ground squirrels spent about half of the year in hibernation. However, differences in timing of the beginning and end of hibernation resulted in differences in the duration of hibernation among age-sex classes. The duration of torpor bouts was short at the beginning of hibernation, increased as Tsoil decreased, reached its maximum toward the end of hibernation, and decreased thereafter. Adult males exhibited hibernation characteristics rather different from those of other age-sex classes, spending less time in hibernation, exhibiting shorter torpor bouts and longer interbout arousals, especially toward the end of hibernation, and spending proportionally less time in torpor. In conclusion, we observed that hibernation patterns in free-living Anatolian ground squirrels were influenced by age-sex classes, as well as environmental conditions.

Black Bears With Longer Disuse (Hibernation) Periods Have Lower Femoral Osteon Population Density and Greater Mineralization and Intracortical Porosity

Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans.

Intensity of parasitic mite infection decreases with hibernation duration of the host snail

Temperature can be a limiting factor on parasite development. Riccardoella limacum, a haematophagous mite, lives in the mantle cavity of helicid land snails. The prevalence of infection by R. limacum in populations of the land snail Arianta arbustorum is highly variable (0-78%) in Switzerland. However, parasitic mites do not occur in host populations at altitudes of 1290 m or higher. It has been hypothesized that the host's hibernation period might be too long at high elevations for mites and their eggs to survive. To test this hypothesis, we experimentally infected snails and allowed them to hibernate at 4°C for periods of 4-7 months. Winter survival of host snails was negatively affected by R. limacum. The intensity of mite infection decreased with increasing hibernation duration. Another experiment with shorter recording intervals revealed that mites do not leave the host when it buries in the soil at the beginning of hibernation. The number of mites decreased after 24 days of hibernation, whereas the number of eggs attached to the lung tissue remained constant throughout hibernation. Thus, R. limacum survives the winter in the egg stage in the host. Low temperature at high altitudes may limit the occurrence of R. limacum.

Live fast, die young: flexibility of life history traits in the fat-tailed dwarf lemur (Cheirogaleus medius)

The fat-tailed dwarf lemur, Cheirogaleus medius, occurs in ecologically very different habitat types (rainforest and dry forest) across Madagascar. Its extraordinary biological characteristics, such as monogamy and long-term hibernation, allow us to investigate behavioral, ecological, and physiological flexibility of this species in populations across different ecological environments. This study aims to determine whether different life history and physiological traits show variation in adaptation to the differing ambient conditions or are conservative and influenced more by the organism's evolutionary history. We compared body masses, life history traits, social organization, and hibernation duration of two populations of C. medius, one from a littoral rainforest and one from the dry deciduous forest. We revealed clear geographical differences in the length of hibernation duration as well as, more surprisingly, in life history traits. We found that this species' reproductive strategies seem to be highly flexible. Animals in the rainforest can spend more time in the active state due to a shorter hibernation period, but have, in general, a shorter life expectancy due to higher mortality rates. Hence, they seem to maximize their total reproductive output with higher reproductive rates (larger litter sizes, greater number of litters). Home ranges and social organization, on the other hand, did not vary between habitats, suggesting that the general requirements of this species are independent of environmental conditions. In conclusion, some life history traits, formerly assumed to be genetically fixed parameters of primate species, prove in fact to be highly flexible. Different populations of the same species show distinct adaptations according to the prevailing conditions in order to maximize individual reproductive output.