Biologging of body temperature in a desert ungulate reveals water use, sex-specific seasonal thermoregulation and heterothermy-associated mortality
Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine
Abstract The inability to properly thermoregulate can be an early sign of physiological stress and indicate poor fitness in mammals. Advances in biologging technology enable continuous monitoring of core body temperature in free-ranging animals, offering insights into thermoregulation. Arid environments are characterized by extreme daily and seasonal fluctuations in temperature and limited water availability. As such, desert animals balance energetic demands of self-maintenance and reproduction against thermoregulatory constraints. In this study, we deployed reticulum implant transmitters (biologgers) in 43 desert bighorn sheep () across six Mojave Desert mountain ranges from November 2020 to December 2021, coinciding with a severe drought. Our aim was to (i) detect and assess frequency of water consumption, (ii) characterize seasonal, population-level and sex-specific patterns in daily body temperature metrics (minimum, maximum, median and amplitude) and (iii) test whether body temperature variability predicted mortality risk. Desert bighorn typically only rely on surface water during the hotter months, but biologgers provided high-resolution, year-round evidence of water consumption, providing novel insights into water usage during a drought year. Females exhibited greater thermal flexibility than males through increased body temperature variation via lower daily minima in the spring and higher daily maxima in the summer. Males were able to lower their body temperature duri
Abstract
Abstract The inability to properly thermoregulate can be an early sign of physiological stress and indicate poor fitness in mammals. Advances in biologging technology enable continuous monitoring of core body temperature in free-ranging animals, offering insights into thermoregulation. Arid environments are characterized by extreme daily and seasonal fluctuations in temperature and limited water availability. As such, desert animals balance energetic demands of self-maintenance and reproduction against thermoregulatory constraints. In this study, we deployed reticulum implant transmitters (biologgers) in 43 desert bighorn sheep () across six Mojave Desert mountain ranges from November 2020 to December 2021, coinciding with a severe drought. Our aim was to (i) detect and assess frequency of water consumption, (ii) characterize seasonal, population-level and sex-specific patterns in daily body temperature metrics (minimum, maximum, median and amplitude) and (iii) test whether body temperature variability predicted mortality risk. Desert bighorn typically only rely on surface water during the hotter months, but biologgers provided high-resolution, year-round evidence of water consumption, providing novel insights into water usage during a drought year. Females exhibited greater thermal flexibility than males through increased body temperature variation via lower daily minima in the spring and higher daily maxima in the summer. Males were able to lower their body temperature during the summer mating season without increasing body temperature variation. Individuals that died exhibited significantly greater body temperature variability via lower daily minima preceding death than did survivors during corresponding periods—an early indicator of increased mortality risk in desert bighorn. Continuous core temperature monitoring via biologgers thus offers a powerful tool for linking physiological state to fitness in the field of conservation physiology.