While most mammals are drab browns and grays, there are a small number of well-known and intriguing exceptions. Perhaps the most famous of all is the giant panda (Ailuropoda melanoleuca), a species of bear native to the mountains of southwest China.
Giant panda Xiao Liwu at the San Diego Zoo.
“It seems that giant pandas appear conspicuous to us because of short viewing distances and odd backgrounds: when we see them, either in photographs or at the zoo, it is almost always from close up, and often against a backdrop that doesn’t reflect their natural habitat,” said Professor Nick Scott-Samuel, a researcher in the School of Psychological Science at the University of Bristol.
“From a more realistic predator’s perspective, the giant panda is actually rather well camouflaged.”
In the study, Professor Scott-Samuel and his colleagues from China, Finland and the United Kingdom analyzed photographs of giant pandas, taken in their natural environment.
The researchers discovered that the animals’ black pelage patches blend in with dark shades and tree trunks, whereas their white patches match foliage and snow when present.
Also, infrequent pale brown pelage tones match ground color, providing an intermediate color which bridges the gap between the very dark and very light visual elements in the natural habitat.
The results are consistent whether viewed by human, felid or canine vision models; the last two represent panda predators.
Next, the scientists examined a second form of camouflage — disruptive coloration, in which highly visible boundaries on the surface of an animal break up its outline; in the panda’s case the borders between the large black and white patches of fur.
They found that giant pandas show this form of defensive coloration especially at longer viewing distances.
Finally, the authors utilized a novel color map technique to compare a similarity-to-background metric across a variety of species, as well as the giant panda.
This comparative analysis confirmed that the background resemblance of the giant panda fell solidly within other species that are traditionally considered as well camouflaged.
Giant panda coloration and its visual background. First row: animals photographed in a zoo (left Beijing zoo, right Chengdu zoo, Wikimedia commons, the rest in nature by Fuwen Wei), exemplifying how black-and-white coloration stands out when viewed close up and/or against an artificial background. Second row: in its natural habitat, the coloration is less conspicuous even at close range. Third row: the camouflage is more evident at intermediate distances and from various angles, and helps the giant panda to blend into its natural environment. Bottom row: from further away, the black-and-white coloration breaks up the outline of the animal due to increased edge disruption. Image credit: Nokelainen et al., doi: 10.1038/s41598-021-00742-4.
“I knew we were on to something when our Chinese colleagues sent us photographs from the wild and I couldn’t see the giant panda in the picture,” said Professor Tim Caro, a researcher in the School of Biological Sciences at the University of Bristol.
“If I couldn’t see it with my good primate eyes, that meant that would-be carnivorous predators with their poorer eyesight might not be able to see it either. It was simply a matter of demonstrating this objectively.”
“The rare photographic evidence allowed us to examine the giant panda appearance in its natural environment for the first time,” said Dr. Ossi Nokelainen, a postdoctoral researcher in the Department of Biological and Environmental Science at the University of Jyväskylä.
“With help of the state-of-the-art image analysis, we were able to treat these images as if the pandas would have been seen by their predator surrogates using applied vision modeling techniques and also to explore their disruptive coloration.”
“Comparative results totally bust the myth of giant pandas being overtly conspicuous in their natural habitat.”
The study was published today in the journal Scientific Reports.
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Ossi Nokelainen et al. 2021. The giant panda is cryptic. Sci Rep 11, 21287; doi: 10.1038/s41598-021-00742-4
Source link: https://www.sci.news/biology/giant-pandas-camouflage-10212.html
