It is the largest of Old World grey wolves, averaging in Europe; however, exceptionally large individuals have weighed between , though this varies according to region. Its fur is relatively short and coarse, and is generally of a tawny colour, with white on the throat that barely extends to the cheeks. Melanists, albinos and erythrists are rare, and mostly the result of wolf-dog hybridisation. The howl of the Eurasian wolf is much more protracted and melodious than that of North American grey wolf subspecies, whose howls are louder and have a stronger emphasis on the first syllable. The two are, however, mutually intelligible, as North American wolves have been recorded to respond to European-style howls made by biologists.