Giant pandas in zoos beyond natural latitude show physical and behavioural symptoms similar to human jet lag, find researchers

Giant pandas living outside the latitude of their native range in China are less active because of differences in daylight and temperature, according to a study by the University of Stirling in Scotland.

The scientists also found that the abnormal and sexual behaviour of the panda subjects in the study shared similar rhythms, suggesting they might be frustrated they could not migrate or mate as they normally would during spring.

The team said zoos could take better care of the captive bears by matching the light, temperature and feeding schedules to their natural rhythms.

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China has long loaned giant pandas to other countries as a sign of goodwill. At least 65 pandas are housed in overseas zoos in 18 countries, including Australia, Britain, France, Japan, Korea, Qatar, Russia, Singapore, Spain and the United States.

Animals synchronise their internal clocks to cues such as light cycles, temperature and seasonal food to sleep or eat at the right times of day and mate at the best time of year.

Keeping animals’ circadian clocks in check is key to maintaining captive populations, particularly those that are vulnerable in the wild, according to the researchers.

Lead author Kristine Gandia said accounting for overnight behaviour, sleeping sites and sleep quality could help improve giant panda welfare because zoos could provide appropriate resources. Photo: Xinhua

But zoo environments differ from the animals’ wild habitats and they may struggle to fully adapt. This could risk disrupting their bodies and behaviours similar to jet lag, metabolism issues or seasonal affective disorder in humans.

In the new study, over a year observers monitored 11 giant pandas via webcams at six zoos inside and outside pandas’ natural latitudinal range of 26 degrees to 42 degrees north. The mirrored latitudes in the southern hemisphere were seen matching their natural latitude.

“Although animals are highly adaptive, creating a captive environment that mimics the environmental conditions for which the animal has evolved can encourage naturalistic cycles that ultimately aid in promoting positive welfare states and increasing chances of successful breeding and conservation,” the researchers wrote in an article published in the peer-reviewed journal Frontiers in Psychology on September 18.

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Lead author Kristine Gandia, a PhD student in the University of Stirling’s faculty of natural sciences, said the giant pandas had three activity peaks over 24 hours, including one at night, just like their wild counterparts.

Meanwhile, adult pandas only displayed sexual behaviour during the day, which could make it easier to find mates in the wild, according to the study.

“Overnight behaviours did mostly consist of sleeping – in sometimes very silly positions – but also interestingly some midnight snacking on bamboo,” Gandia said.

“Accounting for overnight behaviours, sleeping sites and sleep quality could help improve welfare as zoos can provide appropriate resources for their overnight needs if they are aware of them.”

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She said zoos could observe the established relationships between external factors and behaviours “so that they may provide their animals with appropriate choices, enhance conservation efforts, promote circadian synchronicity and consequently improve welfare.”

Similar studies could also be extended to other captive animals, she added.

Comparing animals in highly seasonal environments and those in stable environments would help prove if the former had a higher adaptive range.

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“Research already suggests that animals from environments closer to the equator where environmental factors like light and temperature are consistent year-round have a harder time adapting to the changes caused by climate change,” Gandia said.

She said the next step was to assess pandas’ sexual hormones to understand environmental effects, which could offer insights into how to best support reproduction for the notoriously difficult-to-breed species.