BOISE - Seven elk died after eating a poisonous plant in the Boise foothills near Table Rock, the Idaho Department of Fish and Game said on Wednesday.
The plant - Japanese yew - is commonly used for landscaping in yards.
"Elk are coming out of the high country due to the weather that we're having, and as a result they're ending up in areas in close proximity to neighborhoods," said Regional Conservation Educator Evin Oneale.
Fish and Game officials say a local sportsman found the dead elk scattered over a hillside just below Table Rock Road. Officers initially thought they were dealing with a case of poaching, but after closer examination realized it was something else.
"None of the elk had bullet wounds or other obvious signs of trauma," Conservation Officer Ben Cadwallader said in a statement. "They all appeared to be in great shape, with adequate fat reserves and solid bone marrow; we concluded that we were dealing with some sort of toxin instead."
Field necropsies and an analysis of the animals' stomach contents revealed that Japanese yew was the culprit.
"They die rather quickly," said Oneale. "It takes about a half a cup of yew leaves to kill an adult elk and they die pretty quickly - so sometimes it's within just a few feet of where they're browsing on the plant."
The plant is a common landscaping shrub, despite that fact that it is fatal to a variety of species, including elk, moose, horses, dogs, and even humans.
The use of the plant on properties in the Boise foothills presents a problem for wildlife officials, who say big-game animals often roam into lower elevations during the winter months.
Two sources of the poisonous plant have already been located, but officers are continuing to look for more.
"Because it's so common it's quite possible that an awful lot of the homes up in that area have Japanese yew in their landscaping," said Oneale.
The department is urging all foothills homeowners to inventory their property and remove all Japanese yew that might be growing in their yard.
Mindy Marks lives in the foothills, and after hearing about elk dying from this plant in Hailey, she decided to look in her yard to see if the plant was there.
"We would feel terrible," said Marks. "We're in their natural territory so we would like to respect their migration routes and keep them as healthy as we can."
"We're pretty blessed in Idaho to have the wildlife resources that we have here and living in close proximity to wildlife comes with responsibilities," Oneale said. "This is one of them."
Officers say the problem was compounded by a foothills homeowner who put out hay to feed the heard of 200 elk wintering in the area.
"Despite the winter weather, these elk are in great physical shape and they have adequate forage," Cadwallader said. "The presence of hay only encourages these animals to stay in the immediate area, which could lead to additional animals dying from ingesting Japanese yew needles."
Oneale says if you find Japanese yew in your yard, the best option is to remove it quickly. If you decide to get rid of it, Oneale says to bring it to a landfill - otherwise animals will still be able to get to it.
If you want to keep the plant around, Oneale advises that you cover it with heavy burlap.