LIVINGSTON, Mont. (AP) - An environmental group is building 6-foot-high fenced pens on two sheep ranches in the Paradise Valley where wolves have killed 38 sheep in the past year.

Suzanne Stone, Rocky Mountain field representative for Defenders of Wildlife, said the 4.5-acre enclosures were being built on Bob and Hubie Weber's sheep ranches because other deterrents, including bright flags and noisemakers, had failed to ward off the Lone Bear pack.

Defenders of Wildlife, which pushed for reintroduction of wolves to Yellowstone National Park in 1995, compensates stockgrowers for livestock killed by wolves. The group also pays for deterrents.

Stone said she hoped the fences would eventually become an alternative to killing wolves.

U.S. Fish and Wildlife Service is planning to kill the remaining three wolves in the Lone Bear pack, suspected in all 38 sheep kills. Six in the pack have already been shot by federal officials.

Nine of the sheep kills took place in September on Bob Weber's ranch, who said he was told Defenders wouldn't compensate him for sheep killed in the future unless he had the pens built.

"It's kind of a blackmail deal," Weber said Wednesday.

The organization paid for the Webers' sheep losses last year, when 29 sheep were killed, mostly on Hubie Weber's ranch.

Bob Weber said the 6-foot fence might not be high enough to deter wolves, but said Montana Fish, Wildlife and Parks officials told him if it was any higher it would prevent game migration and injure animals.

Earlier this month, wolves jumped a 5-foot fence in the Paradise Valley and killed two goats.

The enclosures for Bob and Hubie Weber's property will cost about $12,500, which Defenders is raising through donations.