The Giant Panda's Striking Coloration May Stem From Its Poor Diet

Tim Caro, Professor of Wildlife Biology at the University of California, Davis (UC Davis), has made it his mission to understand the evolution of coloration in mammals. The researcher spent twenty years investigating why zebras sport black and white stripes (to ward off flies) and even wrote a book, Zebra Stripes, about his epic discovery. Now, Caro has solved the age-old mystery of why giant pandas also sport the dual coloration.

According to the researcher, “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,”

Over the years, there have been numerous theories to explain the animal’s signature black and white color. Some experts hypothesized that it was to scare predators. Others believed that the white fur provided the mammal with much-needed camouflage in the snow, while the dark patches enabled it to retain heat. There was also the theory that the markings on the panda’s head kept it hidden from predators, while the dark circles around its eyes helped reduce the sun’s glare.

To solve the mystery once and for all, the UC Davis team, who worked in collaboration with scientists at California State University, Long Beach, compared the coloring of different parts of the giant panda’s body to those of 200 carnivore species, including 39 bear subspecies. This was no easy task given that the scientists had to carefully examine thousands of images and seek out the different areas of fur that were similar to those of the giant panda. Once they found a match, they looked further into the carnivore’s evolutionary history to ascertain if it could explain the reason the panda was sporting a similar color.

The team, who published their findings in the journal Behavioral Ecology on February 28, discovered that different parts of the giant panda’s coloring serve different purposes. As had been previously believed, the mammal’s white face, neck, belly, and rump allow it to blend in with the snow during winter. Its black arms and legs are not to retain heat, but to help the panda stay hidden in the shade during summer. This is particularly important for cubs that often perch themselves on tree tops to avoid being seen by predators, like jackals and snow leopards, that share the same mountainous habitat in China. The dark ears help scare off predators, while the black eye patches most likely enable giant pandas to recognize each other and, possibly, show aggression towards competitors.

According to the study, the giant panda’s striking dual coloring may be the result of its poor diet, that comprises primarily of bamboo, which has little nutrition and very few calories. Since the mammals are unable to build up enough fat reserves to allow them to hibernate during the winter, they have no choice but to wander year-round in search of food.

The scientists speculate that instead of developing a summer and winter coat similar to those of small carnivores like the arctic fox, “it [giant panda] has evolved a compromise white and black pelage [fur].”

They maintain that the giant panda is not the only animal that has adopted this evolutionary strategy. Some larger species of wolverines (Gulo gol) that also traverse across several habitats often sport a similar black and white coloring.

Resources: livescience.com, forbes.com,academic.oup.com