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1) Believed to be an ancestor of domestic dog, the wolf is generated (1)... a highly intelligent animal. Wolves travel in packs and their territory can be anywhere (2)... 40 to 400 square miles. As well as marking the borders of their territory with scent, they (3)... other wolves know they are around by barking and howling.

2) A pack might (4)... of up to 30 wolves, although where (5)... 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 (6) ... escape, and finally catch it. In (7) ... way, they are (8) ... to trap large animals, such as deer or moose.

3) If farm animals are available, they (9) ... the wolves with an easy source of food. This, of course, brings then (10) ... contact with humans. Poisoning and shooting have contributed (11)... the decline in wolf populations around the world. The red wolf is now almost extinct (12) ... the wild, while the grey wolf has (13) ... its habitat reduced to a few areas in Europe, North America and Asia. (14) ... mani other large mammals, the wolf is increasingly (15) ... threat from human activity.