U.S. technicians and equipment were sent to the Galapagos Islands, off Ecuador, to join the fight against a stubborn bush fire that is threatening one of the islands' unique ecology. The blaze erupted Feb. 28 and officials twice thought that it had been extinguished. But last week, it started burning again. The wild fire is burning on La Isabela, the Pacific island where Charles Darwin conducted studies leading to the theory of evolution. The area is home to a wide variety of plants, birds and animals--including the Galapagos tortoise, a prehistoric species of giant land turtle.