Coping with heat: behavioural and physiological responses of savanna elephants in their natural habitat

Mole, Michael A.; DÁraujo, Shaun Rodrigues; Aarde, Rudi J. van; Mitchell, Duncan; Fuller, Andrea

doi:10.1093/conphys/cow044

Cited by 69 publications

(59 citation statements)

References 38 publications

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“…This is consistent with the fact that woodlands are the habitat type that provides the most shade needed for thermoregulation. Indeed, diurnal temperature often exceeds body temperature and selection for shade is an important behavioural adjustment of large mammals in hot ecosystems such as African savannas (see Mole et al ., for an example on African elephants Loxodonta africana , Trethowan et al ., for lions). Similar patterns have been observed in the Ongava game reserve (Namibia) where hyaenas have been showed to avoid sites such as hilltops which expose them to weather elements (Stratford & Stratford, ).…”

Section: Discussionmentioning

confidence: 99%

Drivers of diurnal rest site selection by spotted hyaenas

et al. 2017

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Rest sites are key locations to many animals but their selection has been poorly studied in large carnivores. We investigated seasonal diurnal rest site selection by spotted hyaenas (Crocuta crocuta) in Hwange National Park, Zimbabwe. We assessed the effects on hyaena diurnal rest site selection of (1) distance to the nearest waterhole, as waterholes can be considered prey hotspots in the study ecosystem, (2) habitat type and vegetation characteristics, in particular visibility as it influences detection risk and shade for thermoregulation, (3) location within the core territory of their main competitor/predator, the African lion (Panthera leo), where encounter risk would be higher, (4) distance to the closest lion and (5) distance to the nearest road as they can facilitate travelling by carnivores. We defined rest sites as midday locations of hyaenas equipped with GPS collars. Hyaenas preferred to rest in woodland areas with low visibility, close to roads and far from a lion. Distance to the nearest waterhole and location within lion core territory did not affect hyaena rest site selection. Overall, our study points to the combined importance of the structure of the vegetation (providing safety and shade), the availability of roads (to move through and exploit this bushed environment) and the avoidance of proximity to lions.

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Section: Discussionmentioning

confidence: 99%

Drivers of diurnal rest site selection by spotted hyaenas

et al. 2017

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“…Real habitats are much richer in their radiant complexity than in the complexity represented by air temperature, so consideration of radiant heat exchange is essential for proper assessment of the thermal mosaic available to animals (Carroll, Davis, Fuhlendorf, & Elmore, 2016). Even the largest of the terrestrial mammals seek shade (Mole, Rodrigues DÁraujo, van Aarde, Mitchell, & Fuller, 2016), and many species change posture or orientation to modulate the heat absorbed from direct solar radiation (e.g. Maloney, Moss, & Mitchell, 2005).…”

Section: Dry He At E Xchang E: Not Only About Air Temper Aturementioning

confidence: 99%

Revisiting concepts of thermal physiology: Predicting responses of mammals to climate change

Mitchell

Snelling

Hetem

et al. 2018

Journal of Animal Ecology

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196

223

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The accuracy of predictive models (also known as mechanistic or causal models) of animal responses to climate change depends on properly incorporating the principles of heat transfer and thermoregulation into those models. Regrettably, proper incorporation of these principles is not always evident. We have revisited the relevant principles of thermal physiology and analysed how they have been applied in predictive models of large mammals, which are particularly vulnerable, to climate change. We considered dry heat exchange, evaporative heat transfer, the thermoneutral zone and homeothermy, and we examined the roles of size and shape in the thermal physiology of large mammals. We report on the following misconceptions in influential predictive models: underestimation of the role of radiant heat transfer, misassignment of the role and misunderstanding of the sustainability of evaporative cooling, misinterpretation of the thermoneutral zone as a zone of thermal tolerance or as a zone of sustainable energetics, confusion of upper critical temperature and critical thermal maximum, overestimation of the metabolic energy cost of evaporative cooling, failure to appreciate that the current advantages of size and shape will become disadvantageous as climate change advances, misassumptions about skin temperature and, lastly, misconceptions about the relationship between body core temperature and its variability with body mass in large mammals. Not all misconceptions invalidate the models, but we believe that preventing inappropriate assumptions from propagating will improve model accuracy, especially as models progress beyond their current typically static format to include genetic and epigenetic adaptation that can result in phenotypic plasticity.

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“…Water availability and climate conditions, especially environmental temperature, vary widely in space and time, influence the energy and water budgets of terrestrial and semiterrestrial animals, and drive the evolution of functional adaptations to cope with temperature and water constraints (Angilletta, 2009;McKinley, Martelli, Pennington, Trevaks, & McAllen, 2018;Mole, Rodrigues DÁraujo, van Aarde, Mitchell, & Fuller, 2016;Sears et al, 2016).…”

Section: Interpl Ay B E T Ween Temper Ature and Water Con S Tr Aintmentioning

confidence: 99%

When water interacts with temperature: Ecological and evolutionary implications of thermo‐hydroregulation in terrestrial ectotherms

Rozen‐Rechels

Dupoué

Lourdais

et al. 2019

Ecology and Evolution

121

109

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The regulation of body temperature (thermoregulation) and of water balance (defined here as hydroregulation) are key processes underlying ecological and evolutionary responses to climate fluctuations in wild animal populations. In terrestrial (or semiterrestrial) ectotherms, thermoregulation and hydroregulation closely interact and combined temperature and water constraints should directly influence individual performances. Although comparative physiologists traditionally investigate jointly water and temperature regulation, the ecological and evolutionary implications of these coupled processes have so far mostly been studied independently. Here, we revisit the concept of thermo‐hydroregulation to address the functional integration of body temperature and water balance regulation in terrestrial ectotherms. We demonstrate how thermo‐hydroregulation provides a framework to investigate functional adaptations to joint environmental variation in temperature and water availability, and potential physiological and/or behavioral conflicts between thermoregulation and hydroregulation. We extend the classical cost–benefit model of thermoregulation in ectotherms to highlight the adaptive evolution of optimal thermo‐hydroregulation strategies. Critical gaps in the parameterization of this conceptual optimality model and guidelines for future empirical research are discussed. We show that studies of thermo‐hydroregulation refine our mechanistic understanding of physiological and behavioral plasticity, and of the fundamental niche of the species. This is illustrated with relevant and recent examples of space use and dispersal, resource‐based trade‐offs, and life‐history tactics in insects, amphibians, and nonavian reptiles.

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Coping with heat: behavioural and physiological responses of savanna elephants in their natural habitat

Cited by 69 publications

References 38 publications

Drivers of diurnal rest site selection by spotted hyaenas

Drivers of diurnal rest site selection by spotted hyaenas

Revisiting concepts of thermal physiology: Predicting responses of mammals to climate change

When water interacts with temperature: Ecological and evolutionary implications of thermo‐hydroregulation in terrestrial ectotherms

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