Mysteries remain in elk deaths

Elkhunter

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Associated Press — May 24, 2004

RAWLINS, Wyo — Many questions remain surrounding the deaths of more than 300 elk in south-central Wyoming, including the type of toxin in lichen the animals ingested.

The number of afflicted elk in the Red Rim area west of Rawlins stands at 318. The first diseased animals were found in February.

Researchers are certain consumption of tumbleweed shield lichen caused the die-off but are not sure what toxin in the plant is to blame.

"We found levels of 50 percent lichens in their stomachs," said Tom Reed of the Wyoming Game and Fish Department. "That's a lot of lichen and I think it's a food of last resort for them."

The disease weakened the elk's muscles so that they were unable to walk or stand. Those that hadn't died from starvation or dehydration were put to death.

Despite old literature that attributed similar deaths in livestock to usnic acid in lichen, researchers are not sure yet if that was the cause, said Merl Raisbeck, a toxicologist with the State Veterinary Laboratory in Laramie.

"There's no proof yet," he said, adding that the literature may be from as early as the 1930s.

"We've got a lot of questions still," he said. "The basic question is what's the active ingredient in this lichen?"

Usnic acid has anti-bacterial properties and lichen containing it have several uses in traditional medicine, including as a poultice. Put into pills, it can promote weight loss by boosting metabolism.

Sores suffered by the elk though were unusual for usnic acid. Mice and humans who ingest it suffer liver not muscle damage, he said.

Raisbeck has applied for a grant to help confirm whether usnic acid is the culprit.

Among the other issues he wants to study are whether drought affected the lichen or the elk's preference for it.

Lichen is not especially nutritious and often hard for most large animals to eat unless piled in wind rows, he said. Game wardens reported finding piles of lichens in the Red Rim area.

Raisbeck also said the FBI requested that he test for presence of nerve gases. None was found.
 
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