Changes in the skull morphology of the Arctic wolf, Canis lupus arctos, during the twentieth century

Measurements of a large series of skulls of the Arctic wolf, Canis lupus arctos. have shown that since 1930 there has been an overall reduction in the size of the skulls, together with widening of the cranium, shortening of the facial region, and reduction in size of the teeth. This suggests that hybridization and subsequent introgression occurred with huskies (Canis familiaris) during the 1930s, which is consistent with historical accounts. Since 1950 there has been a reversion in skull morphology to a more ‘wolf-like’ form, suggesting that hybridization is no longer occurring. The skull of a wolf/dog hybrid is intermediate in size between the skulls of wolves and huskies but its shape is allometrically dissimilar. Skulls of wolves from the period 1930–50 are moi-e similar to the skull of this hybrid than in the other time periods. The skull of a male canid from a carcass collected on Ellesmere Island and presented to the Natural History Museum. London, in 1986 was at first thought to be from a wolf/dog hybrid but analyses of the measurements show that it is more likely to be from an Arctic wolf with severe abnormalities to the jaws.