Field metabolic rates of giant pandas reveal energetic adaptations

Abstract

Knowledge of energy expenditure informs conservation managers for long term plans for endangered species health and habitat suitability. We measured field metabolic rate (FMR) of free-roaming giant pandas in large enclosures in a nature reserve using the doubly labeled water method. Giant pandas in zoo like enclosures had a similar FMR (14,182 kJ/day) to giant pandas in larger field enclosures (13,280 kJ/day). In winter, giant pandas raised their metabolic rates when living at − 2.4 °C (36,108 kJ/day) indicating that they were below their thermal neutral zone. The lower critical temperature for thermoregulation was about 8.0 °C and the upper critical temperature was about 28 °C. Giant panda FMRs were somewhat lower than active metabolic rates of sloth bears, lower than FMRs of grizzly bears and polar bears and 69 and 81% of predicted values based on a regression of FMR versus body mass of mammals. That is probably due to their lower levels of activity since other bears actively forage for food over a larger home range and pandas often sit in a patch of bamboo and eat bamboo for hours at a time. The low metabolic rates of giant pandas in summer, their inability to acquire fat stores to hibernate in winter, and their ability to raise their metabolic rate to thermoregulate in winter are energetic adaptations related to eating a diet composed almost exclusively of bamboo. Differences in FMR of giant pandas between our study and previous studies (one similar and one lower) appear to be due to differences in activity of the giant pandas in those studies.

Complete Mitogenomes of Ticks Ixodes acutitarsus and Ixodes ovatus Parasitizing Giant Panda: Deep Insights into the Comparative Mitogenomic and Phylogenetic Relationship of Ixodidae Species

“…Our team is developing a program to release captive-bred giant pandas into the wild by adopting the Human-Assisted Soft Release Method. Through this method, our investigators can examine the trained giant pandas and collect more data in the wild without undergoing anesthesia [ 19 , 40 ]. A total of eight adult ticks were collected from the body surface of our wild-training giant pandas living in Yingjing Area of Giant Panda National Park (102°19′30″ E–102°57′0″ E, 29°28′30″ N–29°57′0″ N) from March to April 2022, and stored in 95% ethanol.…”

Ursids evolved dietary diversity without major alterations in metabolic rates

“…One group reported that giant pandas have DEE (41 ± 12 kcal/kg 0.75 /day) similar to the three-toed sloth ( Bradypus variegatus ) and, therefore, much lower than virtually all other terrestrial mammals, including koalas ( Phascolarctos cinereus ) and echidnas ( Tachyglossus aculeatus ) 4 . Those results were contradicted by others who reported DEE three times higher (122 ± 51 kcal/kg 0.75 /day) 5 , 6 . Although housing and diets varied from captive to free-ranging and from only bamboo to mixtures of bamboo and human-type foods, neither group suggested or reported major differences in DEE due to diet or housing 4 – 6 .…”

“…Although housing and diets varied from captive to free-ranging and from only bamboo to mixtures of bamboo and human-type foods, neither group suggested or reported major differences in DEE due to diet or housing 4 – 6 . However, the latter group 5 , 6 suggested that differences in activity might explain the differences in DEE within giant pandas and between giant pandas and other ursids, but that idea was not tested beyond noting that polar bears would have greater energy expenditures for travel and, potentially, thermoregulation than giant pandas 6 .…”

Behavioral thermoregulation in primates: A review of literature and future avenues

“…Reactive oxygen species and heat shock proteins both play integral roles in the heat‐stress response (Paital, 2016; Pires et al, 2019) and might serve as indicators of thermoregulatory function. Likewise, measurement of metabolic rates in the field, while difficult, has proven useful for some mammals (Bi et al, 2021).…”