It was one of the stories in a space frontier collection. A hunter was after the most dangerous game. When killed it had the shape of a small seemingly harmless wormlike creature. But the creature preferred to assume the shape of a large catlike predator and it ran in packs. The hunter takes a guide out on a hunt and realizes from stories the guide tells about the creature that it is telepathic and empathic also and will die if ostracized. He also realizes that the guide is one of the shape changers.