The American Black Bear (Ursus americanus) exhibits a wide range of coat colors, including typical black or brown, as well as shades of cinnamon, blonde, and rare blue-gray. A specific population of these bears can indeed be white, a phenomenon resulting from a unique inherited genetic trait.
The Specific Population of White Black Bears
White-coated black bears are found in the Great Bear Rainforest along the remote coast of British Columbia, Canada. This population is classified as the Kermode bear subspecies (Ursus americanus kermodei). While most Kermode bears are black, a minority possess a creamy white coat, earning them the nickname “Spirit Bears” from the Indigenous peoples of the region.
The distribution of these white bears is highly localized, with the greatest concentration occurring on islands like Gribbell, Princess Royal, and Roderick. On these islands, the white phase can account for 10 to 20 percent of the total Kermode bear population. This geographic isolation is a significant factor in maintaining the frequency of the gene responsible for the white fur.
These bears hold deep cultural significance for the local First Nations, such as the Kitasoo/Xai’xais, who refer to them as moksgmʼol, or white bear. Their existence was protected by the oral tradition of silence, which helped keep the bears safe for generations. Though estimates vary, it is believed that only between 100 and 500 fully white individuals exist in the wild.
Understanding the Genetic Cause of White Fur
The distinctive white coat of the Spirit Bear results from a specific genetic mutation. This coloration is an example of a color polymorphism, where two or more distinct color forms exist within the same population. The mutation responsible is a single nucleotide change within the Melanocortin-1 Receptor gene, commonly known as MC1R.
The MC1R gene is responsible for regulating the production of melanin, the pigment that gives color to fur, skin, and eyes. The specific variant carried by the Kermode bear is a recessive allele. This means a bear must inherit two copies of the altered gene, one from each parent, to express the white coat phenotype.
A black-coated Kermode bear can still carry one copy of this recessive white gene and is considered a heterozygote. When two black bears that are both heterozygotes mate, there is a one-in-four chance that their offspring will inherit two copies of the recessive gene and be born with a white coat. The resulting non-functional change at codon 298 effectively blocks the normal production of dark pigment in the fur, leading to the creamy white color.
Color Variation Versus Albinism and Leucism
The white fur of the Spirit Bear is a specific color phase and must be distinguished from pigment disorders like albinism and leucism. Albinism is characterized by a complete lack of melanin production throughout the body, including the eyes. True albino animals typically have pink or red eyes due to the visibility of blood vessels in the absence of pigment.
In contrast, the Spirit Bear’s condition still allows for some pigment production in the skin and eyes, maintaining dark noses, footpads, and normal eye color—a key distinction from albinism. This genetic difference means the white coat is neither a form of albinism nor the more generalized condition of leucism.
Leucism involves a partial loss of pigmentation, which often results in patchy or spotted white areas across the body. The Spirit Bear’s white fur is a uniform, all-over coloration resulting from the MC1R gene mutation.