Researchers are focused on a herd of elk north of Elko, in the Independence and Tuscarora mountains, that have been mysteriously dying. In some years, 10% to 30% of collared females in the affected population have died.
Ava Window, a University of Nevada, Reno researcher, said what’s puzzling is that the elk are dying during a season when conditions should be working in their favor.
“That’s when there’s the most forage available to them. That’s when they’re having their calves, that’s when the males are growing their antlers,” Window said. “So, this is usually a really good time for them, and the fact that this is when they’re dying is very unusual.”
The phenomenon has an informal name: seasonal elk mortality syndrome. Window and her colleagues are working with the Nevada Department of Wildlife in an attempt to understand what’s causing it.
Affected elk often appear healthy before declining rapidly. Window said examinations have found damage and lesions in their hearts, along with excessive fluid around the heart and in the chest cavity.
One clue is low copper levels in corpses.
Copper is an essential trace mineral that elk get through their diet. But it’s unclear whether the animals aren’t getting enough from the landscape or whether other minerals are interfering with their ability to absorb it.
Window and her colleagues are also analyzing plants, soils and elk diets.
And, the team cautions that it’s too early to say whether the mineral imbalance is what is responsible for the deaths.
“Through the years of this project, we’ve yet to be able to sort of identify the smoking gun that’s actually acting upon the elk and causing mortality,” said Cody McKee, an elk and moose staff specialist with the Nevada Department of Wildlife. “But what remains constant annually seems to be this mineral imbalance that they’re experiencing.”
McKee said those imbalances could weaken the animals’ immune response, potentially leaving them more vulnerable to pathogens or other threats. That means what ultimately kills an elk could differ from year to year, even if the underlying nutritional problem remains.
Similar questions about nutrition have surfaced in other Western elk populations.
A study that included elk from Idaho found a possible link between low selenium levels and a hoof disease affecting elk in the Pacific Northwest. Earlier research in Idaho also found some elk had below-adequate levels of zinc and selenium, while copper was on the low end of the adequate range.
But scientists are still working to understand how mineral imbalances affect wild elk, and whether they contribute to disease or mortality. Window said the Nevada study could help scientists better understand how nutrition affects elk health across the West.
This story was produced by the Mountain West News Bureau, a collaboration between Boise State Public Radio, Wyoming Public Media, Nevada Public Radio, KUNR in Nevada, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio and KJZZ in Arizona as well as NPR, with support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
