Body mass is associated with hibernation length, body temperature, and heart rate in free-ranging brown bears

Frontiers in Zoology

Research

Ole Frobert¹  Boris Fuchs²  Alexandra Thiel²  Alina L. Evans²  Jon M. Arnemo³  Timothy G. Laske⁴  Navinder J. Singh⁵  Jon E. Swenson⁶  Stephane Blanc⁷  Andrea Friebe⁸  Sylvain Giroud⁹ 

[1] Department of Cardiology, Faculty of Health, Örebro University, Örebro, Sweden;Department of Forestry and Wildlife Management, Faculty of Applied Ecology and Agricultural Sciences, Inland Norway University of Applied Sciences, Campus Evenstad, 2418, Elverum, Norway;Department of Forestry and Wildlife Management, Faculty of Applied Ecology and Agricultural Sciences, Inland Norway University of Applied Sciences, Campus Evenstad, 2418, Elverum, Norway;Department of Wildlife, Fish and Environmental Studies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden;Department of Surgery, University of Minnesota, 55455, Minneapolis, MN, USA;Department of Wildlife, Fish and Environmental Studies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden;Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Post Box 5003, 1432, Ås, Norway;Hubert Curien Multidisciplinary Institute, UMR 7178 CNRS/UDS, 23 Rue Becquerel, 67087, Strasbourg, France;Norwegian Institute for Nature Research, 7485, Trondheim, Norway;Reseach Institute of Wildlife Ecology, Department of Interdisciplinary Life Sciences, University of Veterinary Medicine, Savoyenstraße 1, 1160, Vienna, Austria;Energetics Lab, Department of Biology, Northern Michigan University, Marquette, USA;

关键词: Brown bears;    Hibernation;    Heart rate;    Metabolic rate;    Thermal conductance;    Thermoregulation;   

DOI  :  10.1186/s12983-023-00501-3

 received in 2022-09-26, accepted in 2023-06-28,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundDespite 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.ResultsThe 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.ConclusionWe 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.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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