The largest of approximately 41 wild species of canids, gray wolves vary in size based primarily on geographic locality, with southern populations generally smaller than northern populations. Total body length, from tip of the nose to tip of the tail, is from 1000 to 1300 mm in males, and 870 to 1170 mm in females. Tail length ranges between 350 to 520 mm. Males can weigh from 30 to 80 kg, with an average of 55 kg, females can weigh from 23 to 55 kg, with an average of 45 kg. Height (measured from base of paws to shoulder) generally ranges from 60 to 90 cm. Distance between the canines is around 4 cm.
Fur color of gray wolves also varies geographically, ranging from pure white in Arctic populations, to mixtures of white with gray, brown, cinammon, and black to nearly uniform black in some color phases.
North American populations have three distinct color phases. The normal phase is characterized by varying mixtures of white with shades of black, gray, cinnamon, and brown on the upper parts of the animal. The back is usually more profoundly black, and the muzzle, ears, and limbs have cinammon coloration as well. Under parts are whitish and the tail is conspicuously black over the tail gland, and paler below to the tip, which is nearly pure black. The black phase of North American populations is characterized by the upper parts varying from brown to black, with specks of white; the underparts are paler in tone, and there is often a pure white medial pectoral spot. The third color phase occurs during the first pelage of young wolves. The upper parts are drab-gray, overlaid with brownish-black. The underparts are paler as well, and the ears vary from black to buffy, depending on the subspecies (Young 1944).
Gray wolves have a dense underfur layer, providing them with excellent insulation against cold conditions.
Gray wolves can be distinguished from red wolves (Canis rufus) by their larger size, broader snout, and shorter ears. They are distinguished from coyotes (Canis latrans) by being 50 to 100% larger and having a broader snout and larger feet.
Range mass: 23.0 to 80 kg.
Range length: 870 to 1300 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger