The distinctive black and white pattern of giant pandas emerged as a result of two key survival needs – to hide themselves away in a variety of environments and to communicate aggression to predators and other pandas.
Markings and patterns normally emerge as a means of protection for animals. Some patterns provide camouflage, others help attract mates, while they can also help to regulate body temperature.
However, black and white markings are rarely seen in nature. Indeed, there are many theories as to why zebras have black and white stripes – from repelling biting flies to helping them stay cool in the savannah heat. But the reason for the giant pandas markings has remained something of a mystery.
In a study published in the journal Behavioural Ecology, researchers from the University of California, Davis, and California State University, Long Beach, have now looked at 195 different carnivore species to match the patterns with various ecological and behavioural functions.
"Understanding why the giant panda has such striking coloration has been a long-standing problem in biology that has been difficult to tackle because virtually no other mammal has this appearance, making analogies difficult," said lead author Tim Caro. "The breakthrough in the study was treating each part of the body as an independent area."
Their analysis, which included 39 bear subspecies, showed dual purposes for the markings. On their bodies, black and white fur emerged as a result of their poor diet of bamboo. Because they cannot digest a wider variety of plants, they can never store enough energy to go into hibernation. This means they have to continually forage in different environments.
The white fur helps them hide away in snowy habitats during the winter months. Their black markings help them camouflage themselves in tropical forests.
However, their eye and ear markings serve the purpose of communication. Their dark ears help them appear dangerous to predators, while their eyes appear to help them recognise one another: "Dark ears may be involved with signalling intent about ferocity whereas dark eye marks may serve in individual recognition," the team wrote.
"There is no compelling support for their fur colour being involved in temperature regulation, disrupting the animal's outline, or in reducing eye glare. We infer that the giant panda's unique pelage coloration serves a constellation of functions that enable it to match its background in different environments and to communicate using facial features."