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Believed to be an ancestor of the domestic dog, the wolf is generally regarded as a highly intelligent hunter. Wolves travel in (1) _ and their territory can be anywhere from 40 to 400 square miles. As well as marking the borders of their territory with scent, they (2) _ other wolves know they are around by barking and howling. A pack might consist of up to 30 wolves, although where the food supply is limited there might only be six or seven animals in the pack. When hunting, they work together to chase an animal, block its escape, and finally (3) _ it. In this way, they are (4) to trap large animals, such as deer or moose.
If farm animals are available, they (5) _ the wolves with an easy source of food. This, of course, brings them into (6) _ with humans. Poisoning and shooting have (7) _ to the decline in wolf populations around the world. The red wolf is now almost (8) _ in the wild, while the grey wolf has had its (9) _ reduced to a few areas in Europe, North America and Asia. Like many other large mammals, the wolf is increasingly under (10) _ from human activity.