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The secret life of Giant Pandas

Giant pandas, Ailuropoda melanoleuca, have usually been regarded as solitary creatures, coming together only to mate; but recent studies have begun to reveal a secret social life for these enigmatic bears.  GPS tracking shows they cross each others path more often than previously thought, and spend time together.  What we don't know is what they are doing when together. 

Photo by Sid Balachandran on Unsplash

For such large mammals, pandas have relatively small home ranges. Perhaps this is no surprise. Pandas feed almost exclusively on bamboo. The only real threat to pandas has come from humans. No wonder then that the panda is the symbol of the WWF.  Pandas communicate with one another through vocalization and scent marking. They spray urine, claw tree trunks and rub against objects to mark their paths, yet they do not appear to be territorial as individuals. 

Pandas are 99% vegetarian, but, oddly, their digestive system is more typical of a carnivore. For the 1% of their diet that isn't bamboo, pandas eat eggs, small animals, carrion, and are known to forage in farmland for pumpkin, kidney beans, wheat and domestic pig food.  It is thought these bears switched to eating bamboo, in part because it's extremely abundant and they don't have to fight with other animals to get it. Bamboo is high in fibre but has a low concentration of nutrients. So pandas have to eat 20 to 40 pounds of the stuff every day survive. 

It is not clear if giant pandas are promiscuous, but out of the wild, pandas mate more successfully when they are free to choose their mate. This could also explain the poor breeding success in captivity. This is a significant ingredient in reproductive success across all species, and vital for species adaptation. Reproduction isn't simply about replication, but about change and variability. Charles Darwin also thought this to be a significant selection for survival and evolution. 

Pandas sleep a lot, taking regular naps throughout the day simply lying on the ground or resting up against a tree, balancing on a branch. Much of their time is spent eating. 

The iconic black and white panda is actually the Sichuan giant panda, one of two subspecies. Their recently discovered cousins are the brown-furred Qinling giant pandas. New research published in Science Bulletin has used state-of-the-art technology to genome sequence both subspecies to understand when the Sichuan and Qinling pandas diverged; and why giant pandas have small organs and difficulty reproducing. 

The research concludes that the two subspecies diverged around 10-12 kya (thousand years ago), far more recently than previous estimates of 300 kya. Giant pandas have relatively small organs, including “diminutive penises”. A number of genes associated with reproductive performance, including sperm production and male genitals, exhibited unique evolutionary traits in the giant panda genome, which may be partially to blame for the giant panda’s low reproductive rate.

Ray Noble is a chartered biologist and Fellow of the Royal Society of Biology


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