Acclimation and energy metabolism of the dingo, Cards dingo and the coyote, Canis latrans

Abstract

Twelve dingos were divided into three groups each containing four animals. One group was warm‐acclimated at +30° to +45°C, the second cool‐acclimated at −20° to − 40°C and a third control group was kept in animal quarters maintained at about +23°C. Three coyotes were also kept in animal quarters but they had free access to outside runs which they used during all seasons. The four warm‐acclimated animals tolerated temperatures of +45°C at 25% relative humidity with a mean rectal temperature of 39.3°C and a mean O2 consumption rate of 8.2 ml/kg min. Cool‐acclimated dingos became distressed at ambient temperatures between +37.5 and +42.5°C and at 40% relative humidity the mean rectal temperature of this group was 40.6°C. The O2 consumption rate of one animal at an ambient temperature of +42.5°C was 16.7 ml/kg min. The mean minimum O2 consumption rate for the warm‐acclimated group in its thermal neutral range was 4.4 ml/kg min and the comparable rate for the cool‐acclimated group was 7.8 ml/kg min, a difference of 77% in their standard metabolic rates. At an ambient temperature of −70°C the mean O2 consumption rate of the four warm‐acclimated animals was about six times the mean rate recorded in their thermal neutral range. Despite this high energy usage all had low rectal temperatures and were frostbitten when they were removed from the chamber. The cool‐acclimated animals increased their O2 consumption rates by a factor of only 2.2 at −70°C when compared with the standard rate in their thermal neutral zone. At −70°C the mean O2 consumption rate of the cool‐acclimated group was only 69% of the warm group mean. With this lower energy usage they maintained their rectal temperature at normal values and did not suffer any frostbite. The weight of fur insulation per unit area increased in the cool‐acclimated animals and in some body areas the mean value was three times that of the corresponding mean for the warm‐acclimated group. When calculated from the slope of the O2 consumption vs. ambient temperature relation below the lower critical temperature the cool‐acclimated group had 64% more insulation than the warm‐acclimated group. The three coyotes had a mean O2 consumption rate at −70°C (17.7 ml/kg min) which was about equal to that of the cool‐acclimated dingos at the same ambient temperature. This rate was 2.4 times the standard metabolic rate in their thermal neutral zone and is about the same proportional increase as that shown by the cool‐acclimated dingos. However the lower critical temperature of the coyotes (−10°C) was much lower than that of the cold‐acclimated dingos (+ 10°C). When compared with other canid studies these results suggest that, even when acclimated to heat, dingos have a tolerance of high temperatures which is little or no better than that of the domestic dog. When held at −70°C cool‐acclimated dingos maintained their body temperatures with moderate energy expenditure but even so were not as metabolically economical as the wolf or the husky but were comparable with the coyote. It is concluded th...

Winter space use of coyotes in high-elevation environments: behavioral adaptations to deep-snow landscapes

“…Resource selection is dependent on balancing energy expenditures associated with locomotion versus energy intake from prey while minimizing predation risk. Deep snow and cold temperatures, both characteristic of harsh winter climates, can exacerbate locomotion costs for cursorial predators (Shield 1972;Crete and Lariviere 2003) causing a high energetic budget and the need for acquiring substantial food resources. Because of these energetic demands, behavioral and/or morphological adaptations are necessary for a species to effectively travel, hunt, and exploit resources within such deep snow habitats, as demonstrated in Canada lynx (Lynx canadensis) and snowshoe hare (Lepus americanus; Murray and Boutin 1991;Lesage et al 2001;Murray and Larivière 2002).…”

Accelerometer informed time-energy budgets reveal the importance of temperature to the activity of a wild, arid zone canid

“…Seasonal differences of DEE in free-ranging eutherian mammals have been found in several species, though this is the first time it has been observed in a wild canid. It has been shown that dingoes are capable of acclimating physiologically to extreme temperatures (-41°C to +45°C) over the course of a few months by shifting their TNZ and altering their BMR (Shield 1972). This was observed in concert with a change in thermal conductance brought about by altered coat composition (Shield, 1972).…”

“…We calculated DEE using time-energy budgets calculated from our ACC derived behaviours and equations derived from the literature. For resting metabolic rate (applied to all stationary behaviours) we used oxygen consumption data from dingoes collected by Shield (1972) and derived the following equation (Eq 1) for VȮ2 against Ta.…”

“…Australia's largest terrestrial predator, the dingo Canis dingo, is a medium-sized eutherian carnivore that persists in a wide range of environments (Fleming et al, 2001). Dingoes have been shown to acclimate physiologically to both extreme heat and cold by shifting or extending their thermoneutral zone (TNZ) and altering thermal conductance, effectively minimizing their basal metabolic rate (BMR) and energy expenditure (Shield 1972). For populations in the harsh, resource-limited deserts of central Australia where risks of hyperthermia are high, survival depends on making daily choices that minimise behavioural energetic expenditure (and evaporative water loss), whilst optimising the acquisition of beneficial resources (e.g., food, shelter, water).…”

Evolution and function of fossoriality in the Carnivora: implications for group-living

“…Mammals exposed to cold winter conditions cope through two mechanisms; (i) low thermal conductance to minimize heat loss (e.g., thick winter fur and/or insulating fat layer: Shield, 1972;McNab, 1983); or (ii) by reducing their exposure to the cold, through the use of refugia (Noonan et al, 2014(Noonan et al, , 2015, and/or entering a torpid state therein (Harlow, 1981;Lyman, 2013). Thus, while endothermy allows carnivores to exploit cold regions, and higher latitudes (Grigg et al, 2004), fossoriality provides a means of mitigating temperature thresholds (Shelford, 1931;Pörtner, 2002), permitting the species to live in colder FIGURE 3 | Consensus tree of the Feliformia based on phylogenetic relationships from Agnarsson et al (2010).…”