Tail length ranges between 350 to 520 mm. 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. 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. They occupy a wide variety of habitats, from arctic tundra to forest, prairie, and arid landscapes. Gray wolves are one of the most wide ranging land animals. However, due to habitat destruction, environmental change, persecution by humans, and other barriers to population growth, gray wolf populations are now found only in a few areas of the contiguous United States, Alaska, Canada, Mexico (a small population), and Eurasia. The original range of Canis lupus consisted of the majority of the Northern hemisphere - from the Arctic continuing south to a latitude of 20° S, which runs through southern Central Mexico, northern Africa, and southern Asia.