To really answer this question, let’s start by looking back at some brown bear taxonomy (the branch of science concerned with classification, especially of organisms) history, shall we?
Bear taxonomy went through many revisions before scientists recached the conclusion of Ursus arctos.In the nineteenth and twentieth centuries, taxonomists frequently lumped and split brown/grizzly bears into many different species and subspecies. In 1918 the separation peaked with the publication of C. Hart Merriam’s “Review of the Grizzly and Big Brown Bears of North America.” Merriam proposed around 80 species and subspecies of North American brown bears existed. Merriam’s nuanced classifications of brown and grizzly bears were based on differences in skull morphology and dentition, which he examined in painstaking detail. Merriam classified on southeast Alaska’s Admiralty Island alone, there was 5 distinct subspecies and in the Katmai region, 2 distinct subspecies as well as other living in the Cook Inlet area and on the Kenai Peninsula. But most of the species or subspecies described by Merriam were later regarded as local variations or individual variants. As of the mid 1980’s as many as 9 extant or extinct subspecies of U.arctoswere recognized in North America.
Which brings us to the age old saying “All grizzly bears are brown bears but not all brown bears are grizzlies”. Now even with all the research done by Merriam this saying still has some backing to it. Now a days there are only 3 main subspecies of brown bears recognized by most of the scientific community, Kodiak brown bears, Alaskan Coastal brown bears and Grizzly brown bears. These bears are very similar but still have their differences to classify them as different subspecies. The 2 big determining differences are size and location. Each of the subspecies are geographically and genetically isolated from the other subspecies of brown bear.
Kodiak brown bears (Ursus arctos middendorffi) which main populations are only found on Kodiak Island in Alaska are the largest of the brown bear subspecies. Now these bears are not genetically different enough to be classified as their own species but are distinct enough that they can be classified as their own subspecies because they been isolated from mainland bears for over 12,000 years. Now these bears can get up to 1,500lbs and stand up to 10ft tall. Kodiak brown bears can get this big because they live on islands and they have access to a marine-driven food resource all year round with their favorite being salmon!
The next subspecies, very similar to Kodiak brown bears, are the Alaskan Coastal Brown Bears (Ursus arctos gyas). These bears are known as the ABC island bears because their populations are only found on Admiralty, Baranof, and Chichagof island in southeast Alaska. Alaskan Coastal brown bears can reach large sizes as well, they can reach up to 1,200lbs and stand around 8 ½ to 9ft tall. Just like the Kodiak brown bears, Alaskan Coastal brown bears can reach this size because of their access to marine-driven food resources all year round with their favorite being salmon too! Alaskan Coastal brown bears are unique because they are the most genetically different compared to all other brown bears. Alaskan Coastal brown bears actually share more genetic information with polar bears than other brown bears. This could be due to interbreeding with a small isolated number of polar bears during the last ice age. As more recently, scientists have found more Alaskan Coastal brown bears with polar bear DNA in the northern parts of Alaska suggesting that there has been more interbreeding recently and possibility creating a new bear species, currently known as a “Prizzie”!
The final subspecies is the most common of the three and the reason for the main question of this post, Grizzly brown bears (Ursus arctos horribillis). Grizzlies are considered the smallest of the 3 brown bears subspecies. On average, grizzly brown bears only reach up to 900lbs and 7ft tall. Grizzly brown bears are much smaller because they are inland bears with there main populations found in southwestern Canada and the lower 48 states, they do not have easy access to a marine-driven, high calorie food resource. So Grizzly brownbears must work a little harder for their food, so they don’t build up as much fat as compared to the other 2 subspecies of brown bear. Grizzly brown bears are also known for that distinct hump on their backs. That hump is pure muscles from their shoulders as is usually used as a key morphological identifier for Grizzly brown bears. Grizzly brown bears are also found to be a bit more reactive to humans being around in the distance. This doesn’t not mean they are more aggressive than the other brown bear subspecies, but it is a behavior picked up because Grizzly brown bears are in more human populated areas compare to the other subspecies who live on mostly unpopulated islands. All three subspecies have about the same temperament.
Now that you have the facts, what do you think? Is it a brown bear or is it a grizzly? Do you agree with the statement of “All grizzly bears are brown bears but not all brown bears are grizzlies?” or do you think more research needs to be done? Let us know by leaving a comment