Unlike other mammals who are typically active either during the day or night, giant pandas may have a unique body clock which keeps them active in the morning, afternoon and midnight, a new study has found.
A team led by scientists at Michigan State University (MSU) that has spent years getting unprecedented peeks into panda habits courtesy of five animals with GPS collars has learned their daily routines fall out of the ordinary.
Most mammals fall into three categories of movement: Nocturnal animals are only active at night. Diurnal animals are active during the day.
Pandas were thought to fall into the third category: crepuscular, those who are active twice a day, at dawn and dusk.
But Jindong Zhang, a research associate in MSU's Centre for Systems Integration and Sustainability, found that pandas may belong to a category all their own.
His colleagues have been studying the data that has poured from the advanced GPS collars on five pandas in the Wolong Nature Reserve in southwestern China.
The five pandas - three female adults named Pan Pan, Mei Mei and Zhong Zhong, a young female Long Long and a male dubbed Chuan Chuan - were captured, collared and tracked from 2010 to 2012.
Zhang mapped how active the pandas were across 24-hour periods and across seasons. He found that there were three activity "peaks" throughout the day - in the morning, afternoon, and midnight.
"We cannot simply say the panda is a crepuscular creature. Giant pandas show complex activity patterns that are closely related to food quality and water availability," Zhang said.
"They need to eat food more frequently, such as at midnight, since the nutrition quality of bamboo is low. The study of the activity patterns of pandas opens a door to discovering the unique adaptations of pandas to their environment," said Zhang.
The researchers think that the pandas' unusual diet may account for what apparently is an extra burst of activity. Pandas eat only bamboo, yet digest less than 20 per cent of what they consume.
Vanessa Hull, a co-author on the research paper, thinks this new insight into their movements fits into the pandas' unique place in the food chain.
"Many herbivores have a kind of crepuscular foraging strategy because they want to avoid predators and/or humans that are usually active during the day, so they eat as much as they can at dawn and dusk," Hull said.
"But with pandas, they don't have any major predators, so they can afford to adjust their activity patterns to their own schedule and not worry about running into something that would eat them. It is just interesting to see that they take advantage of this," said Hull.
The research was published in the Journal of Mammalogy.