Lichen is to blame for poisoning elk

[BearHunter]

A deaths of close to 300 elk in Wyoming's southern Red Desert this winter, state officials said Sunday.

The announcement ends a grim mystery that had baffled wildlife researchers across the continent since early February. But it raises new and potentially troubling challenges for biologists who will be studying the episode in the coming years.

"This lichen is all over the place out there," said Tom Reed, a spokesman for the Wyoming Game and Fish Department. "These elk were apparently turning to this because of the drought conditions, so we have to evaluate what steps we can take to prevent it from happening again if the drought continues."

Wildlife veterinarians had suspected the lichen played a role in the die-off when they found it in the stomachs of several of the 290 dead elk found spread across a 50-square-mile area southwest of Rawlins.


On Sunday, their suspicions were confirmed when a bull elk being fed a diet of only lichen at a research facility in Sybille collapsed and was unable to rise. A second elk, a cow, also began stumbling in an apparent reaction to poisoning by usnic acid, a toxic compound contained in the frail green desert plant. Researchers expect the third elk in the study to succumb quickly. All three will be euthanized.

"It's identical to what we're seeing in the field," said Walt Cook, the Wyoming Game and Fish Department veterinarian leading the inquiry. "He's bright and alert, but he just can't get up. They were watching when it happened and he just kind of stumbled and went to the ground."

Many of the stricken animals found in the Red Rim country south of Interstate 80 since February were alert and barked in alarm at the approach of people. Biologists euthanized about 200 elk to end their suffering. The rest died only after enduring days or weeks of exposure to the Wyoming winter.

The lichen, Parmelia molliuscula, is widespread across an area extending from North Dakota to the Rockies. But an elk kill of this magnitude not directly related to winter starvation has never before been documented.

Other herbivores, including cattle, horses and pronghorn, shared the same ground as the elk this winter - apparently without ill effect.

Lichen are a symbiotic organism. Part algae and part fungus, lichen flourishes in cold, dry habitats such as Arctic tundra or alpine summits that are too extreme for most other plants. But lichens contain compounds, such as the usnic acid in Parmelia, that can be difficult for some animals to digest.

Cook and other researchers theorize that a chain reaction of several factors combined to precipitate the die-off. However, it will take further research to test their ideas.

One of the first tasks will be to examine samples of muscle tissue from the three captive elk to see if they show the same damage seen in dead or dying elk found in the rolling steppe of the Red Desert. That is where coyote hunters first reported the elk were collapsing from an unknown ailment.

Researchers had noticed that both the wild elk and research elk discharged red-colored urine, which Cook now suspects was caused by usnic acid eating away at the animals' muscles.

"Healthy muscle looks like red meat," said Cook. "What we were seeing is pale in color. It looks more like chicken or pork."

The long drought afflicting the region may have allowed levels of usnic acid to build up to toxic levels in the region's lichen. Fifty years ago, during another long drought, agricultural researchers documented similar ailments among cattle and sheep in the state. Cook said more of the plants will be collected and analyzed to see if acid concentrations are higher than elsewhere.

Unlike livestock, which recovered from usnic acid poisoning in the 1950s study, the ailment was 100 percent fatal for elk stricken this winter.

Researchers may examine whether the sick elk, part of a herd of about 4,500 that summer in the Sierra Madre Mountains along the Colorado border, lacked the right kind of microorganisms in their stomachs to neutralize the acid. Biologists noted that another herd of desert-adapted elk wintering just north of I-80 did not fall victim to lichen poisoning. Perhaps the desert elk to the north are avoiding the lichen or perhaps they are more tolerant of it, scientists speculate.

One result of the mass poisoning: The agency will cut back on the number of elk licenses to hunters for the areas where the Sierra Madre herd will be found this coming fall, Reed said. The band of 400 to 600 elk afflicted by lichen poisoning was made up mostly of cows, calves and yearling bulls. Biologists estimate that the lichen killed perhaps 5 percent of the herd's breeding females, a loss that will take more than a year to recoup.

Reed said the agency will have to consider other steps, such as improving the range conditions on the Red Rim Wildlife Management Area, to provide healthier forage in the coming years.

"If we have to chase those elk every time we see them chewing on lichen, it's going to get time-consuming," Cook added.

 

[gwhunter69]

Mysterious deaths of Wyoming elk solved; animals died after feeding on lichen
Mon Mar 22,12:55 PM ET

SARAH COOKE

CHEYENNE, Wyo. (AP) - 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.


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 80 kilometres 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 US 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.


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 five per cent 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.

 

[buck59]

posted 3/26/04


Elk killed by acid used for dieting; Natural ingredient in lichen also found in weight-loss pills Associated Press

CHEYENNE, Wyo. - Usnic acid, a substance found in some weight-loss diet supplements, is suspected as the natural ingredient in lichens that may have caused the deaths of more than 300 elk in Wyoming in recent weeks, scientists say.

The elk ingested usnic acid by eating lichen, and some scientists theorize that the chemical was what caused the animals to weaken and collapse - too helpless to eat, drink or escape predators.

After six weeks of uncertainty over what was causing the illness, researchers concluded that the culprit was tumbleweed shield lichen, which is olive-colored and shaped like a well-used scouring pad.



The lichen grows on the ground in many northern states, including Wyoming's sagebrush high country, and healthy captive elk fed the lichen developed the same fatal illness.

Researchers suspect usnic acid was the cause because it was extracted from the lichen. Also, usnic acid poisoning has been previously documented in livestock, though cattle tend to recover.

But some questions remain to be answered before scientists are willing to state a definite conclusion. For example, if usnic acid was to blame, why were the muscles of diseased elk whitish and sickly looking while the animals' livers appeared healthy? In humans, liver toxicity has been the worry.

"That's one of the reasons we don't want to chalk this up to usnic acid at this point," said Walt Cook, a wildlife veterinarian at Wyoming's state veterinary lab in Laramie. "Either the usnic acid is affecting the elk differently or it's not usnic acid at all. … There may well be other compounds in there that may be the toxic compounds."

But John Lehmann, president of the Wayne, Pa.-based drug information outlet DrugIntel, said it would not be surprising that usnic acid could affect elk differently than humans. 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.

But side effects of usnic acid have been questioned before. In January, Food and Drug Commissioner Mark B. McClellan said more study is needed of three diet drugs, including usnic acid. And in 2001, the Food and Drug Administration asked Syntrax Innovations Inc. of Cape Girardeau, Mo., to stop selling Lipokinetix, a diet drug containing usnic acid, saying it was to blame for "a number of serious liver injuries" in some people who used the drug more than two weeks.

Lipokinetix is no longer on the market, but usnic acid is still readily available over the Internet.

"As we learn of the information and evaluate the science behind it we'll proceed accordingly," said Kimberly Rawlings, an FDA spokeswoman.