For the second time in four years, lichens are the likely suspect in the death of large numbers of elk in south-central Wyoming’s Red Rim area. Scientifically known as Parmelia molliuscula, the lichen contains a toxin that first paralyzes elk, then eventually kills them. Four years ago, 300 elk out of a herd of 800 died after eating the lichen. (See “Was it really lichens?” May-June 2005 Bugle.) So far this year, 80 animals out of a herd that now numbers 500 have succumbed due to eating lichen. Although a few elk had only small amounts of the plant in their rumens, the majority had stomachs full of the toxic plant.

	Paralyzed by toxic lichens, this bull awaits death in Wyoming’s Red Rim country. Photo by Greg Hiatt

After eating the lichen, elk slowly begin to lose motor control. Before long they are unable to stand, and though still lucid they cannot move.

This past March, Wyoming Game and Fish officials put down the animals as they lay paralyzed on the snow. Many of the carcasses have been examined and specialists are investigating further, looking for the cause of the lethal reaction. Results are still inconclusive.

“We want to be able to diagnose for lichen rather than just ruling out other diseases,” says Becky Dailey, a Ph.D. candidate in Veterinary Science at the University of Wyoming. “The toxicity of the lichen seems to vary based on environmental conditions.” Toxicity was high in both the winter of 2004 and this past winter. Both winters were especially harsh, leaving the elk to forage on whatever they could find.

As snow melts and more country begins to green up, the elk are moving away from the lichen in favor of their usual spring range areas.

Although the elk have moved on to greener pastures, more may die from the effects of the poison. Experts discovered red urine, a tell-tale sign of toxic lichen ingestion, along the elk’s trail away from the Red Rim area. The Wyoming Game and Fish Department will continue to monitor the herd as the year progresses and the elk cycle back to cold-weather grounds.