With their rounded heads, bamboo diet and mild temperament, pandas are one of the animal kingdom’s most unique creatures. Need more proof? It’s all there in black and white.
Assistant Professor Dr. Ted Stankowich is an Evolutionary Behaviorist in the Biology department in the College of Natural Sciences and Mathematics. He and his student research assistants joined a team of biologists from the University of California, Davis to study the question of why pandas’ external coloration has stark contrasts and what it means.
In a four-year study, scientists studied thousands of color grids and images and compared the colorings of 195 carnivore species and 39 bear subspecies, then matched their patterns against their environments.
Stankowich said the team concluded that the panda’s color patterns serve as both camouflage and communication. Behavioral Ecology published their findings in February 2017.
The research showed that carnivores who have white or light fur on their bodies and necks tend to live in more snowy environments. Carnivores who have dark or black shoulders tend to live in a forest environment. Temperature made little difference.
But pandas? China, where they reside, has both climates and the pandas’ coloration reflects how active they are year-round in both environments. Their white heads and bodies blend in with the snow, while their dark arms and legs are hidden in the shade.
The scientists concluded that the panda’s stark coloration stems from its solitary diet of bamboo, which lacks the nutrients that enable other bears to hibernate or go dormant in the winter. This leaves the panda having to travel great distances to forage year-round in varying habitats, from snowy conditions to shaded forests.
Graduate student and research assistant Hannah Walker said studying the coloration of the panda was challenging. “Pandas are unique – they’re a one-off – there’s no other mammal with a color pattern quite like a giant panda,” Walker said. “So, we can’t look at a lot of other species and say ‘It looks like the more time you spend in snowy and forested habitats, the more you look like a giant panda.’”
To study the panda, the team had to break down the bear into its constituent body parts and ask themselves, why would a carnivore sport black shoulders and legs on a white body? Why does the panda have a white face? Like a jigsaw puzzle, they slowly put the pieces together.
The team started its methodical study of the most common and best-known wild mammals – the Order Carnivora, the most diverse in size of any mammalian order, ranging from dogs and cats to badgers and bears. Then they divided the panda’s generalized carnivore shape and separated it into 13 body and 12 face sections. Finally, they gathered photos to represent as many carnivore species as they could, roughly 2,500 pictures of 195 species.
For each animal pictured, they gave each visible body section a color score, which gave the scientists an idea, on average, of how light or dark their shoulders or ears were, for example. They then compared the “averaged” colors to the environmental factors, such as snowfall, temperature, or habitat, as well as aspects of their social systems.
“We think they are trying to compromise or balance their coloration pattern to be cryptic or camouflaged in both types of environments,” Stankowich said. “We think this is an attempt to hide themselves year-round in the environments they encounter.”
The research also pointed to how the panda’s diet affects its coloration. Pandas only eat bamboo, a nutritionally deficient plant that does not allow them to build up enough energy to hibernate like other bears, which forces pandas to travel year round to find food.
This means, part of the year, they live in forests, where the dark patches of fur help them blend in with the shady floor. During winter months, pandas travel to higher altitudes, so their white patches allow them to blend into a snow-covered landscape as they search for food.
“That conflict is fairly unique among the carnivores,” Walker said. “So their body coloration is really a compromise between those two habitats to be camouflaged from potential predators during the entire year.”
The panda’s face, with the dark circles around the eyes and black ears, convey a different sort of message, Stankowich said. The scientists concluded pandas communicate with these features.
“The ears might be signaling how ferocious or dangerous or pugnacious they are, how willing you are to defend yourself,” Stankowich said.
He said when they look across various species, animals with darker ears tended to be more ferocious or dangerous. Black ears may also help pandas express aggression.
“They may be using them as a signal (by moving them) and it may accentuate the face in a way that makes them appear to be more ferocious. The eyes may be used to signal that as well.”
Stankowich said the pandas’ eye patches vary in shape and size, and previous research has suggested that it correlates with how dominate a bear behaves. The patches also help pandas recognize each other, or signal hostility.
Stankowich told LiveScience.com that sometimes it takes a “Herculean effort”, not to mention hours of hard work and research to answer the simplest of questions, which in this case is – why are pandas black and white?
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