Defenders of Wildlife has offered $1,500 for information leading to the arrest and conviction of those responsible for killing a female grizzly and her two cubs on the Blackfeet Indian Reservation. The government is offering $1,000. The carcasses of the 14-year-old female and the cubs were discovered in a clearing near a road on May 5. The U.S. Fish and Wildlife Service is investigating. Killing a grizzly can lead to a fine of up to $10,000 and six months in prison and is a violation of Blackfeet tribal law with separate tribal penalties. The adult bear had been studied by wildlife managers for 12 years. She had avoided conflicts with humans. "To have a family group of bears killed is disturbing and we would like to find out who did it," federal grizzly recovery coordinator Chris Servheen said. He could not recall a more blatant situation involving grizzlies, protected under the Endangered Species Act. Because grizzlies have a low reproduction rate, losing three bears - and particularly a female of reproductive age - can have a significant impact on the region's grizzly population, he said. Females do not breed until they are four or five years old, and they usually have just one or two cubs every other year.