Researchers studying sleeping pandas and pandas at play reveal that these mostly herbivorous bears don’t actually have exceptionally low metabolic rates – unlike the way they’re portrayed. Temperature, and not bamboo, will be the limiting factor in their successful reintroduction, according to new findings published in Scientific Reports this week.
Reintroducing captive giant pandas (Ailuropoda melanoleuca) into the wild is a major goal. But can their appetite be supported out there in nature reserves? Wild giant pandas eat 13.1 to 14.6 kilograms (29 to 32.2 pounds) of bamboo leaves and stems a day, or 43.7 kilograms (96.3 pounds) of shoots a day. During the 1980s, parts of China suffered a large-scale bamboo die-off. And while the crisis has since subsided, researchers lack sufficient knowledge of panda physiological ecology to determine their requirements for survival now – and in the face of imminent climate change.
A team led by Drexel University’s James Spotila and Zhihe Zhang from the Chengdu Research Base of Giant Panda Breeding (Panda Base) wanted to see if current bamboo resources were sufficient for adding additional pandas to populations in natural reserves. So they measured the active and resting metabolic rate of several giant pandas at the Panda Base in Sichuan Province, China, during the summer and winter seasons.
The team found that panda active metabolic rates were in the normal range, and their resting metabolism is just below average for mammals of their size. It was just a little lower than seals, deer, oryx, and kangaroos. Previous studies put their daily energy expenditure at only 37.7 percent of predicted values based on size. That means there’s enough bamboo in natural reserves to support both natural populations and large numbers of reintroduced pandas – at least until climate warming upsets their ecosystem. And even if bamboo doesn’t limit the success of panda reintroduction, the effect of temperature on the pandas themselves might.
Giant pandas could get heat stress if temperatures rise above 25°C (77°F). "They have to live at temperatures below that to stay healthy," Spotila explains in a statement. "In nature, they actively seek out cool areas (microhabitats) in summer and move to higher elevations to avoid heat."
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