Tiptoeing through the icy waters of rich salmon streams are the silvery paws of an elusive animal. An unsuspecting Salmon brushes past his fixed figure, causing him to lunge and grasp and splash. He’s ready to eat, and lunch swims closer to him than it does to his darker furred relatives. He walks on. Using his broad paddles, he turns over rocks – hunting for any other fresh aquatic produce. He stands on his strong hind legs, his pink nose twitching in the breeze as he delicately plucks berries and fruits from the branches. Fading into the rainforest, he see’s the ancient but familiar conifers that tower in every direction. There are 1,000-year-old cedar trees, and above him 90-metre tall Sitka spruce trees. It’s safer up there. That’s where he will nest for the night. Moss covers the scattered logs on the ground; bringing new shades of green into view. He watches as beams of light struggle to pierce through the canopy. The Great Bear Rainforest stretches for 400 km’s – the size equivalent of Ireland. He steps into a beam. Glistening. It catches and warms his dense fur, illuminating his pale rounded body. He’s like a pearl, hidden in the lush greens and browns that surround him. Still, he eludes many that long to see him.
I won’t lie, for a long time I thought there was only one white coloured bear in the world. That’s until I lived in Canada and learnt about the inhabitants of the Great Bear Rainforest. And no, it’s not a small polar bear, it’s actually a subspecies of the North American black bear – called the Kermode Bear (pronounced ker-moh-dee). It’s a white, black bear. Also known as the Spirit Bear, the scientific name is Ursus americanus kermodei. And it is the official provincial mammal of British Columbia. Scroll down to learn more!
North American black bears can be found in the coastal rainforest along the west side of British Columbia. Within there, the Kermode bear is mostly found on 3 islands. These islands are called Gribbell, Princess Royal, and Roderick Island. The estimated population of bears with the Kermode phenotype is only 100-400 individuals. Making them a rare sight to see.
Kermode bears are not Albano. Kermodism, (the white coloured coat) is the result of a single nucleotide gene mutation. The mutation is in the MC1R gene, and it is recessive. This means that in order for a bear to have white fur, it must carry two of the mutated genetic alleles. One from each parent. In other words, it must carry a homozygous recessive genotype. A bear with two different alleles (a heterozygote) will appear black – as will bears with homozygous black alleles. A study by Ritland, et al. (2001) explains that the mutated ‘white’ allele was quite frequent on the three island populations (Gribbell, Princess Royal, and Roderick). There, they found that the allele frequency ranged from 20% to more than 50%. Whereas on the mainland and other islands, the Kermode allele was quite rare.
Furthermore, additional studies found that the white Kermode bears breed more with other white Kermode bears, and black Kermode bears breed more with black Kermode bears. This is a phenomenon known as positive assortative mating. This could explain why the white allele is rare on the mainland where most bears are of the black variety. It also may explain why Kermodism remains common on the three islands observed despite the kermode allele being recessive.
Like with many things in life, being white has it’s advantages. Although these white privileges are thankfully nothing to do with unethical injustices imposed by society that we unfortunately see in human societies. But that’s a rant for another article. With the Kermode bear, being white helps them to catch more fish!
In fact, Reimchen and Klinka (2017) show that white Kermode bears have more marine derived nutrients in their fur, indicating that white Kermode bears eat more salmon than the black Kermode bears. This means that the white bears exhibit an ecological niche differentiation to their black bear relatives. This could be another reason for the sustained frequency of the white Kermode allele in North American black bear populations.
The reason why white bears are more successful at catching salmon than black bears is all to do with the salmon’s underwater perspective. Underwater, the white bears body appears to be more camouflaged against the sky, compared to the more contrasting dark bears. Klinka and Reimchen, (2009) devised an experiment to test this. They found that the salmon evade large, black models about twice as frequently as they evade large white models. Therefore, the white bears gain an advantage in salmon hunting.
But salmon isn’t all that the spirit bears eat. Spirit bears are omnivores, so during months where salmon are not readily available, the bears feast on a range of different foods. Foods including fruits, berries, nuts, grasses, roots, other plants, insects, crustaceans, fawns and carrion.
First Nations communities have also lived in the Great Bear Rainforest region for thousands of years. They view the animal as sacred, and call the spirit bear moskgm’ol, which simply means ‘white bear’.
I guess they don’t call it the Great Bear Rainforest for nothing.
References used:
- Ritland, K., Newton, C. and Marshall, H.D., 2001. Inheritance and population structure of the white-phased “Kermode” black bear. Current Biology, 11(18), pp.1468-1472.
- Klinka, D.R. and Reimchen, T.E., 2009. Adaptive coat colour polymorphism in the Kermode bear of coastal British Columbia. Biological Journal of the Linnean Society, 98(3), pp.479-488.
- Reimchen, T.E. and Klinka, D.R., 2017. Niche differentiation between coat colour morphs in the Kermode bear (Ursidae) of coastal British Columbia. Biological Journal of the Linnean Society, 122(2), pp.274-285.
- https://www.discoverwildlife.com/animal-facts/mammals/facts-about-spirit-bear/
Featured image: Kemode bear sow and cub at Spirit Bear Lodge, Klemtu, British Columbia, Canada (by Maximilian Helm) cc .
