The species is monotypic with no living subspecies. There is now agreement that there are two species, each with two subspecies. Two subspecies, and , are considered extinct. Coloration varies widely based on subspecies, forms and habitat. It also shares a further 10 endemic subspecies of bird with Corsica. Habitat characteristics can vary depending on subspecies and range. Northwestern wolves are one of the largest subspecies of wolves. Three wild subspecies of aurochs are recognised. All the subspecies, varieties, and cultivars are interfertile. Genetic differences between the two subspecies are obscure. Genetic analyses have tested the existence of three of these putative subspecies. Hybrids are usually reported from areas where ranges of two subspecies overlap. They have characteristics that differ from other brown bear subspecies. Males of the nominate subspecies weigh while females weigh . The Alaska moose is the largest North American subspecies of moose.