How pandas got their patches

Giant pandas’ patches are among the most striking of any mammal: black ears and eye spots set against a white face, with dark limbs and shoulders abutting a white neck and torso. Scientists have proposed dozens of reasons for the animals’ piebald appearance. They could be warnings, like the black and white stripes on skunks. Or they could be used for camouflage, communication, eye protection, or regulating body heat. To find out which ideas were on the mark, scientists compared panda pelage to the dark and light coloring of 195 other terrestrial carnivore species and 39 bear subspecies, and then matched their patterns against environmental conditions and social behaviors. The scientists did not find a link between temperature and coat color; nor did they find an association between black eye markings and daytime glare. But they did find a connection between lighter colors and snow cover, suggesting that the giant panda’s white markings help hide the animal in snowy habitats, they report today in Behavioral Ecology. Meanwhile, their darker markings likely hide them in the forest, where they are preyed on by predators like leopards. Pandas evolved both colors as a kind of compromise, the scientists argue, because they are active year-round in both habitats. But what about the face patches? The analysis indicates that markings on carnivores’ heads are not used for camouflage, but to communicate. Species with strongly contrasting hues between ears and face tended to be fierce, and they suggest pandas may also use their ears to signal warnings to predators. The eye patches may help them recognize one another. Other studies have shown that pandas remember these patches, which vary greatly in size and shape. They can also enlarge them when staring at a competitor. As lovable as we may find those patches, pandas don’t: They cover their eyes with their paws when they don’t want to look aggressive.

V. Altounian/Science