Deaths of 300 elk blamed on plant acid

updated 3:42 p.m. ET March 22, 2004

A lichen native to the Rockies has been blamed for the deaths of at least 300 elk in southern Wyoming, a mystery that had baffled wildlife scientists and cost the state thousands of dollars, the state said Monday.

Wildlife veterinarians had suspected the lichen after finding it in the stomachs of many of the elk that died in south-central Wyoming.

To confirm their suspicions, three elk were fed the lichen at research facility. One collapsed and was unable to rise Sunday, the Wyoming Game and Fish Department said. A second elk also started stumbling and a third is expected to succumb quickly, officials said. All three will be euthanized.

The ground-dwelling lichen, known as Parmelia molliuscula, produces an acid that may break down muscle tissue, said Walt Cook, a Wyoming Game and Fish Department veterinarian leading the inquiry.

Native elk not affected
Elk native to the area weren’t affected by the acid, but those killed in the die-off apparently had moved in from Colorado and may have lacked microorganisms needed to neutralize the acid, state biologists said. The Colorado line is 50 miles south of the area where the elk died.

“Elk don’t normally winter down on the ... unit where they ate the lichen,” Game and Fish spokesman Tom Reed said.

“Elk are incredibly adaptable, tough animals. They’ll get by on thin rations and they’ll make do somehow. But this year, nearly 300 of them paid the price for that adaptability,” Reed said.

The first sick elk was found on Feb. 6 and scientists quickly ruled out chronic wasting disease, the deer and elk version of mad cow disease. They also eliminated most viruses and bacteria, malnutrition, exposure to heavy metals such as arsenic, and poisoning from a leaky gas well or pipeline.

The search for the cause became expensive. For a time, researchers used a helicopter to search for afflicted elk, but the flights cost $900 an hour. Wildlife experts also drove into the rough country near the Continental Divide and slogged through melting snow and mud to collect plant specimens and elk droppings.

Why so acidic?
Scientists still want to know more about the lichen and why it contained high amounts of the acid this year.

“There are a lot of factors we’ll need to look at,” Reed said. “Do elk eat this lichen in normal years? If so, why hasn’t this happened before? Does a long history of drought weigh in somehow? If so, what are our management options in the future?”

The die-off killed up to 5 percent of the Sierra Madre herd’s breeding females, and that will affect hunting quotas this fall and could trigger wildlife policy changes, Reed said.

Other steps, such as improving range conditions to provide healthier forage, will also be considered as researchers learn more and try to prevent future die-offs.

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