Here is a discussion on this very subject on Reddit (I was not the author):
" The myth of “Canadian Gray Wolf” comes from deliberate mis-interpretation of common colloquial names (timber wolf, etc.) and the term sub-species. The “timber wolf” is simply another name for the gray wolf. There is no such thing as a “Canadian Gray Wolf.” It is a term that has been embraced by the anti-wolf crowd and is purely fiction. Common names for animals can vary from place to place. For example, the terms cougar, puma and mountain lion all refer to the same animal. California calls them mountain lions, Oregon and Washington call them cougars. South America calls them pumas. Florida calls them panthers. Timber wolf is just another name for the gray wolf. The terms brush wolf and prairie wolf are old names for the coyote.
What is a sub-species? A sub-species is a regional variant of a species, similar to a breed of domestic animal. Nature creates subspecies, humans create breeds. A German Shepard, for example, is a different breed than a Siberian Husky, but their both still the same species of dog (Canis familiaris). Subspecies are part of the speciation process, where a population is genetically isolated long enough to evolve characteristics that make it genetically incompatible with the original population and thus its own species but are not distinct on their own. Currently in North America, there are five recognized subspecies of the gray wolf. These are all the same species of wolf: Canis lupus. Geographic separation and habitat has given rise to regional variants that have some minor distinct characteristics, but are still genetically the same species. These are:
The arctic wolf (Canis lupus arctos*), found on the Canadian archipelago islands;
The eastern wolf, also called the eastern timber wolf or Algonquin wolf (Canis lupus lyacon), found in eastern Canada and formerly the U.S. northeast; The plains wolf, also called the buffalo wolf (Canis lupus nubilis), formerly found across the Great Plains, now found in central Canada and the Upper Midwest; The Mexican gray wolf, also called the lobo (Canis lupus balieyi), formerly found throughout northern Mexico and the American southwest, now reintroduced to small portions of their former range in New Mexico, Arizona and northern Mexico; The western gray wolf, also called the Rocky Mountain gray wolf (Canis lupus occidentalis), formerly widespread across the mountainous regions of western North America.
Historically, species and subspecies were labeled based on physical characteristics like skull morphology, coat color and size. Modern genetics have replaced this system. The taxonomists (scientists that name and study species and subspecies) of the 1800s and 1900s were going off of physical characteristics when designating species and tended to favor breaking a species into many separate subspecies based on minute differences. This system had problems. With some species of birds that display sexual dimorphism, the males and females were thought to be separate species until they were observed mating, for example. Black and gray-coated wolves were thought to be separate species, until it was shown that both could be born in the same litter. Early taxonomists designated some 40-odd different sub-species of the gray wolf in North America. Genetic analysis of historic specimens of these “subspecies” had shown that by and large, they did not show enough genetic diversity to be considered a valid classification. Subspecies like the northern Rocky Mountain gray wolf (Canis lupus irremotus), the southern Rocky Mountain gray wolf (Canis lupus youngi), and the Texas wolf (Canis lupus monstrabilis) did not actually exist and were instead the western gray wolves (C. l. occidentalis) and Mexican gray wolves (C. l. balieyi) respectively. Mutliple genetic studies analyzing the genes of historic wolf specimens (those killed prior to reintroduction efforts), wolves naturally expanding their range back into the American west, mostly in northwestern Montana, and those reintroduced into Yellowstone and central Idaho from Canadian populations have shown that there is zero genetic difference in these wolves. They are the same species. They are the same subspecies. They are native. Here is a study looking for genetic markers used in identifying native and non-native wolves. Here is another one looking specifically at the genetics of wolves from the Pacific Northwest and California and comparing historical specimens to modern wolves. Here is a link to JSTOR"
" The idea that wolves in Canada are somehow a larger, more vicious, more dangerous species is unscientific, unproven, and unsupported by all genetic and biological research. Gray wolves in Canada are the same species as gray wolves in Mexico, Europe, and the Middle East. Furthermore, gray wolves in the Northern Rockies are the same subspecies, Canis lupus occidentalis. Occidentalis is native to the American west. We do not have a distinct species or subspecies of wolf that begins or ends at the Canadian border. Wolves routinely disperse (leave their birth pack to find a mate) over thousands of miles. OR-7 was not an outlier, this is common behavior. This dispersal behavior spreads genetic information across huge geographic areas and prevents the geographic isolation necessary for a distinct species or subspecies to arise.
The wolves reintroduced to Yellowstone National Park and central Idaho came from two populations in the Canadian Rockies, the first near Hinton, Alberta (near Jasper National Park) and the second from Fort St. John, British Columbia. These areas were selected specifically because they were similar in both habitat and prey base to Yellowstone and Idaho. They were not Mexican wolves. Gray wolves had begun migrating down from Canada on their own and repopulating part of northwestern Montana in the 1980s. These wolves have been shown, through genetic testing, to have come from the region near Jasper National Park, the same location that the wolves for the 1995 reintroduction effort were sourced."
" Wolves are wolves. There is no behavioral difference between wolves occurring in Canada and wolves occurring the lower 48. This belief that Canadian wolves are more aggressive, more dangerous or form bigger packs is fiction and found only in the anti-wolf narrative. Wolves in far northern Canada and Alaska are slightly larger than those found at lower latitudes, however. There can be a 10%-20% size difference. Mexican gray wolves are the smallest North American subspecies, weighing in at 60-80 lbs., while the Great Plains wolves (Canis lupus nubilis) of Canada’s Wood Buffalo National Park have been known to weigh in closer to 150 lbs. Harvest records from Idaho, Montana and Wyoming show that the average weight of the wolves killed in legal hunts post-reintroduction are 90-110 lbs. for males and 80-100 lbs. for females. This is within the range of historical reports from the same regions. Wolves in Yellowstone have weighed in at record weights, with two males from one pack weighing in at 141 lbs. and 148 lbs., the largest wolves recorded in the U.S. Both of these wolves were from the Mollie’s pack, an interior Yellowstone pack known for hunting bison. Mollie’s pack wolves tend to run larger than the park average and this is thought to be due to the fact that they are bison hunters. Bigger prey both provides more food and requires larger wolves to take down. Wolves, whether Mexican gray wolves or Rocky Mountain gray wolves, preform the same function in the ecosystem. If every Mexican wolf died tomorrow, wolves from the Northern Rockies could be introduced to the Southwest to fill the gap with no impact. This has already been done with elk. The original elk of the Southwest, the Mirriam’s subspecies, was wiped out. The same happened with the Manitoba elk and Eastern elk. Rocky Mountain elk have been introduced into parts of country inhabited by those extinct subspecies to fill the gap. Rocky Mountain elk now live in Tennessee, Wisconsin, Arizona, New Mexico and California, among other places. The species matters, the subspecies does not. Carter Niemeyer put it very well during the early arguments over wolf reintroduction to Yellowstone: “Canis lupus irremotus? More like Canis lupus irregardless.” The gray wolf is the gray wolf, whether found in Canada or Mexico. Nature writer Rick Bass put it a different way in his book The New Wolves, in reference to Rocky Mountain elk released in the mountains of the Southwest to replace the extinct Merriam’s elk, but it applies to wolves as well: “They are the same language, just a slightly different dialect. The land still recognizes them.” "