The fauna of Vancouver Island is similar to that found on the mainland coast, with some notable exceptions and additions. For example, mountain goats, moose, coyotes, porcupines, skunks, chipmunks, and numerous species of small mammals, while plentiful on the mainland, are absent from Vancouver Island. Grizzly bears are absent from the island, where black bears are prevalent, but in 2016, a pair of grizzlies were sighted swimming between smaller islands off the coast near Port McNeill. Vancouver Island does support most of Canada's Roosevelt elk, however, and several mammal species and subspecies, such as the Vancouver Island marmot are unique to the island. Columbian black-tailed deer are plentiful, even in suburban areas such as in Greater Victoria, as well as the native Douglas squirrels. The Eastern grey squirrel is found in the south and is considered invasive for its voracious appetite and scaring away of the Douglas squirrels. The island has the most concentrated population of cougars in North America. The Vancouver Island wolf, a subspecies of grey wolf, is found only on the north part of the island. Harbour seals and river otters are common.