Pups begin to howl at one month old. Survival Threats Human encroachment into wolf territory is the largest single survival threat to wolves. Wolves need open land and an abundant supply of prey to survive. The illegal killing of wolves is a serious problem, especially for small populations. Almost one-quarter of the wolves in Minnesota are illegally killed each year.
Wolves are an exception among the animals.
Apart from humans, no other mammal has a bigger natural distribution. From the high tundra in the north to the rain forests of the south, in the high mountain regions as well as in the steppe, in the Earth's last wilderness regions and immediate vicinity of humans it manages every environment, as a hunter of large prey or making use of garbage, as loners as well as in the pack. Its adaptability is second to the human's only, and its inner species variation even beats humans. There are completely white or black wolves, maroon and grey ones. There are wolves weighting not more than 50 pounds and others, more northwards, that weight four times as much.