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Knowledge of factors influencing the timing of reproduction is important for animal conservation and management. Brown bears (Ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. Body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. We compared mean daily body temperature and activity levels of pregnant and nonpregnant females during preimplantation, gestation, and lactation. Additionally we tested whether age, litter size, primiparity, environmental conditions, and the start of hibernation influence the timing of parturition. The mean date of implantation was 1 December (SD = 12), the mean date of parturition was 26 January (SD = 12), and the mean duration of the gestation period was 56 days (SD = 2). The body temperature of pregnant females was higher during the gestation and lactation periods than that of nonpregnant bears. The body temperature of pregnant females decreased during the gestation period. Activity recordings were also used to determine the date of parturition. The parturition dates calculated with activity and body temperature data did not differ significantly and were the same in 50% of the females. Older females started hibernation earlier. The start of hibernation was earlier during years with favorable environmental conditions. Dates of parturition were later during years with good environmental conditions which was unexpected. We suggest that free-ranging pregnant brown bears in areas with high levels of human activities at the beginning of the denning period, as in our study area, might prioritize investing energy in early denning than in early parturition during years with favorable environmental conditions, as a strategy to prevent disturbances caused by human.

While capture-mark-recapture studies provide essential individual-level data in ecology, repeated captures and handling may impact animal welfare and cause scientific bias. Evaluating the consequences of invasive methodologies should be an integral part of any study involving capture of live animals. We investigated short- and long-term stress responses to repeated captures within a winter on the physiology, behaviour, and reproductive success of female Svalbard reindeer (Rangifer tarandus platyrhynchus). Short-term responses were evaluated using serum concentrations of glucocorticoids and catecholamines during handling, and post-release recovery times in heart rate and activity levels. Repeated captures were associated with an increase in measured catecholamines and glucocorticoids, except cortisone, and delayed recovery in heart rate but not activity. Four months later, in summer, individuals captured repeatedly in winter exhibited a small increase in behavioural response to human disturbance and had a lower probability of being observed with a calf, compared to animals not captured, or captured only once. Our findings imply that single annual capture events have no significant negative consequences for Svalbard reindeer, but repeated captures within a season may impact offspring survival in the same year. Such unanticipated side effects highlight the importance of addressing multiple indicators of animal responses to repeated captures.

Seasonal energetic challenges may constrain an animal's ability to respond to changing individual and environmental conditions. Here, we investigated variation in heart rate, a well-established proxy for metabolic rate, in Svalbard reindeer (Rangifer tarandus platyrhynchus), a species with strong seasonal changes in foraging and metabolic activity. In 19 adult females, we recorded heart rate, subcutaneous temperature and activity using biologgers. Mean heart rate more than doubled from winter to summer. Typical drivers of energy expenditure, such as reproduction and activity, explained a relatively limited amount of variation (2–6% in winter and 16–24% in summer) compared to seasonality, which explained 75% of annual variation in heart rate. The relationship between heart rate and subcutaneous temperature depended on individual state via body mass, age and reproductive status, and the results suggested that peripheral heterothermy is an important pathway of energy management in both winter and summer. While the seasonal plasticity in energetics makes Svalbard reindeer well-adapted to their highly seasonal environment, intraseasonal constraints on modulation of their heart rate may limit their ability to respond to severe environmental change. This study emphasizes the importance of encompassing individual state and seasonal context when studying energetics in free-living animals.

We conducted thirteen immobilizations of previously collared hibernating two- to four-year-old brown bears (Ursus arctos) weighing 21-66 kg in central Sweden in winter 2010 and 2011 for comparative physiology research. Here we report, for the first time, an effective protocol for the capture and anesthesia of free-ranging brown bears during hibernation and an assessment of the disturbance the captures caused. Bears were darted in anthill, soil, or uprooted tree dens on eleven occasions, but two bears in rock dens fled and were darted outside the den. We used medetomidine at 0.02-0.06 mg/kg and zolazepam-tiletamine at 0.9-2.8 mg/kg for anesthesia. In addition, ketamine at 1.5 mg/kg was hand-injected intramuscularly in four bears and in six it was included in the dart at 1.1-3.0 mg/kg. Once anesthetized, bears were removed from the dens. In nine bears, arterial blood samples were analyzed immediately with a portable blood gas analyzer. We corrected hypoxemia in seven bears (PaO(2) 57-74 mmHg) with supplemental oxygen. We placed the bears back into the dens and antagonized the effect of medetomidine with atipamezole. Capturing bears in the den significantly increased the risk of den abandonment. One of twelve collared bears that were captured remained at the original den until spring, and eleven, left their dens (mean ± standard deviation) 3.2±3.6 (range 0.5-10.5) days after capture. They used 1.9±0.9 intermediate resting sites, during 6.2±7.8 days before entering a new permanent den. The eleven new permanent dens were located 730±589 m from the original dens. We documented that it was feasible and safe to capture hibernating brown bears, although they behaved differently than black bears. When doing so, researchers should use 25% of the doses used for helicopter darting during the active period and should consider increased energetic costs associated with den abandonment.

Background Despite centuries of research, debate remains on the scaling of metabolic rate to mass especially for intraspecific cases. The high variation of body mass within brown bears presents a unique opportunity to study the intraspecific effects of body mass on physiological variables. The amplitude of metabolic rate reduction in hibernators is dependent on body mass of the species. Small hibernators have high metabolic rates when euthermic but experience a drastic decrease in body temperature during torpor, which is necessary to reach a very low metabolic rate. Conversely, large hibernators, such as the brown bear ( Ursus arctos ), show a moderate decrease in temperature during hibernation, thought to be related to the bear’s large size. We studied body mass, abdominal body temperature, heart rate, and accelerometer-derived activity from 63 free-ranging brown bears (1–15 years old, 15–233 kg). We tested for relationships between body mass and body temperature, heart rate, and hibernation duration. Results The smallest individuals maintained lower body temperatures during hibernation, hibernated longer, and ended hibernation later than large bears. Unlike body temperature, winter heart rates were not associated with body mass. In summer, the opposite pattern was found, with smaller individuals having higher body temperature and daytime heart rates. Body mass was associated with body temperature in the winter hypometabolic state, even in a large hibernating mammal. Smaller bears, which are known to have higher thermal conductance, reached lower body temperatures during hibernation. During summer, smaller bears had higher body temperatures and daytime heart rates, a phenomenon not previously documented within a single mammalian species. Conclusion We conclude that the smallest bears hibernated more deeply and longer than large bears, likely from a combined effect of basic thermodynamics, the higher need for energy savings, and a lower cost of warming up a smaller body.

Background Wild and captive European moose ( Alces alces alces ) are routinely anesthetized with drug combinations including alpha-2 adrenoceptor agonists, dissociative anesthetics, and opioids. Reportedly, severe respiratory depression, ventilation/perfusion (V/Q) mismatch, and hypoxemia are common complications in this species, requiring perianesthetic oxygen supplementation as key treatment, athough high flow rates can exacerbate respiratory acidosis. Salbutamol is a β 2 -adrenoceptor agonist effective in alleviating V/Q mismatch and hypoxemia in anesthetized horses when administered via endotracheal tube. Administration of salbutamol could elicit similar effects in anesthetized moose, improving animal welfare and perhaps reducing or replacing the supplemental oxygen requirements. Case presentation Three healthy captive moose (two juveniles, male and female, and one adult male) underwent four anesthetic events for routine zoo health assessments. One juvenile was anesthetized again after 15 days and served as its own control. Moose were anesthetized with medetomidine (0.05–0.08 mg kg −1 ), ketamine (1.7–2.8 mg kg −1 ), and butorphanol (0.04–0.07 mg kg −1 ) intramuscularly (IM). Intranasal oxygen (1 L min −1 100 kg −1 ) was administered, and they were allocated to receive either 10 mL saline (control) or aerosolized salbutamol. Salbutamol was administered incrementally at 200, 400 and 800 µg 100 kg −1 , with 10-minute monitoring intervals following each dose, using one of three methods: a spacer, an equine intranasal (IN) tube, or an equine medical mask. Invasive blood pressure, electrocardiogram, respiratory rate, SpO2, and rectal temperature were recorded every 5 min. Arterial blood gases and electrolytes were measured before oxygen supplementation and both before and 10 min after each salbutamol dose. Anesthesia was reversed with IM atipamezole (0.3–0.4 mg kg −1 ), and all moose were monitored for seven days post-anesthesia for adverse effects. All moose were hypoxemic, hypercapnic, hypertensive, and tachypneic. No hypotension or hypokalemia occurred. PaO₂ increased in all individuals, with no consistent difference between treatment and control. The largest PaO₂ increase occurred in the moose receiving salbutamol via the IN tube. Other physiological variables remained stable. Recoveries were uneventful, with no adverse effects observed. Conclusion Aerosolized salbutamol was well tolerated, but did not provide a clear benefit for hypoxemia compared to placebo. Further studies with higher salbutamol doses, alternative delivery routes, or modified anesthetic protocols are recommended.

Background Mammals in the far north are exposed to extreme seasonal changes in environmental conditions, such as temperature and photoperiod, which have notable effects on animal physiology and behaviour. The wolverine ( Gulo gulo ) is a carnivore with a circumpolar distribution and well-adapted to extreme environmental conditions. Still, ecophysiological studies on free-ranging wolverines are lacking. In this study, we used abdominally implanted body temperature loggers in combination with GPS collars with acceleration sensors on 14 free-ranging wolverines in northern Sweden to study daily and seasonal variation in body temperature and activity patterns. We used generalized additive mixed modelling to investigate body temperature patterns over time and Lomb-Scargle periodogram analysis to analyse circadian rhythms. Results We found that wolverines have an average core body temperature of 38.5 ± 0.2 °C with a daily variation of up to 6 °C. Body temperature patterns varied between reproductive states. Pregnant females showed a distinct decrease in body temperature during gestation. Wolverines were active both in day and night, but displayed distinct activity peaks during crepuscular hours. However, body temperature and activity patterns changed seasonally, with a gradual change from a unimodal pattern in winter with concentrated activity during the short period of day light to a bimodal pattern in autumn with activity peaks around dusk and dawn. Wolverines were less likely to display 24-h rhythms in winter, when hours of day light are limited. Conclusions The combination of different biologging techniques gave novel insight into the ecophysiology, activity patterns and reproductive biology of free-ranging wolverines, adding important knowledge to our understanding of animals adapted to cold environments at northern latitudes.

Background Effective conservation requires understanding the behavior of the targeted species. However, some species can be difficult to observe in the wild, which is why GPS collars and other telemetry devices can be used to “observe” these animals remotely. Combined with classification models, data collected by accelerometers on a collar can be used to determine an animal’s behaviors. Previous ungulate behavioral classification studies have mostly trained their models using data from captive animals, which may not be representative of the behaviors displayed by wild individuals. To fill this gap, we trained classification models, using a supervised learning approach with data collected from wild red deer ( Cervus elaphus ) in the Swiss National Park. While the accelerometer data collected on multiple axes served as input variables, the simultaneously observed behavior was used as the output variable. Further, we used a variety of machine learning algorithms, as well as combinations and transformations of the accelerometer data to identify those that generated the most accurate classification models. To determine which models performed most accurately, we derived a new metric which considered the imbalance between different behaviors. Results We found significant differences in the models’ performances depending on which algorithm, transformation method and combination of input variables was used. Discriminant analysis generated the most accurate classification models when trained with minmax-normalized acceleration data collected on multiple axes, as well as their ratio. This model was able to accurately differentiate between the behaviors lying, feeding, standing, walking, and running and can be used in future studies analyzing the behavior of wild red deer living in Alpine environments. Conclusion We demonstrate the possibility of using acceleration data collected from wild red deer to train behavioral classification models. At the same time, we propose a new type of metric to compare the accuracy of classification models trained with imbalanced datasets. We share our most accurate model in the hope that managers and researchers can use it to classify the behavior of wild red deer in Alpine environments.

Background Selenium (Se) is an essential element for mammals, with a relatively narrow safety margin between deficiency and toxicity. It is involved in the function of many vital activities and systems, including antioxidants, immune system, thyroid activity, muscle metabolism, and growth by composing different proteins and enzymes. Northern Europe is a Se deficient region, and livestock have been supplemented with mineral bolus or similar for decades to counteract Se deficiency, whereas Finland even adds Se to fertilizers to supplement soil, plants, animals and humans. Relatively few studies have investigated total Se concentrations ([TSe]) in wildlife, and here we present [TSe] measured in whole blood in moose ( Alces alces ), brown bears ( Ursus arctos ), wolves ( Canis lupus ), and wolverines ( Gulo gulo ) from Norway and Sweden. Results [TSe] in whole blood increased with the trophic level of the species: herbivorous moose < omnivorous bears < carnivorous wolves < scavenging wolverines. Compared to established reference ranges of [TSe] in domesticated species, more than half of all moose sampled and 5% of brown bears were Se deficient. Surprisingly, 49% of bears, 42% wolves and 29% wolverines had [TSe] above recommended references range for domesticated species. In general, [TSe] significantly increased with age and body weight in all sampled species, whereas for most species, there was an additional association with region, year, and season sampled, reflecting variations in Se uptake caused by the element’s geochemical properties related to bedrock and soil availability and atmospheric precipitation. Conclusions Further studies should focus on a wider spatial distribution for these animals and especially include more wolverines to investigate the relatively high [TSe] observed in this species. We also emphasize the importance of measuring Se in poor regions for ecotoxicology studies, since Se deficiency can exacerbate heavy metal toxicosis.