In mid-January, at least five elk calves in the Florence area of the Bitterroot Valley succumbed to ingestion of toxic ornamental plants. Homeowners discovered the deceased animals between January 15th and January 23rd. Necropsies performed on two of the calves identified high concentrations of Japanese yew (Taxus cuspidata) in their stomachs. Inspections of residential properties in the vicinity revealed multiple instances of the plants, leading to the voluntary removal of these specimens by homeowners.
Japanese Yew, an evergreen shrub indigenous to East Asia, is frequently utilized in landscaping around residential properties. The plant poses a particular threat to wildlife during the winter months when heavy snowfall can drive ungulates closer to human habitation in search of food.
“Because it’s not native to the area, animals aren’t familiar enough with the plant to know or teach their young that it’s toxic,” stated area biologist Rebecca Mowry in a press release. “Even a small amount can kill them, and yearlings are especially susceptible.”
According to Wildlife Veterinarian Jennifer Ramsey of the Montana Fish, Wildlife & Parks (FWP), ingestion of Japanese Yew in quantities exceeding one percent of an elk’s body weight is sufficient to result in mortality.
“The elk we necropsied here at the wildlife health lab had a large amount of yew – leaves, stems, and seeds – in its rumen,” explained Jennifer Ramsey. “Yew toxicity often causes sudden death, commonly within two to four hours after ingestion.”
Japanese Yew has been implicated in numerous major die-offs among ungulates throughout the Rocky Mountains. Following a heavy snow event in 2016-2017 in Idaho, 23 elk and 50 pronghorn were reported deceased as a result of this plant. In addition, several yearling elk perished that year in the vicinity of Hamilton and Darby, with further incidents occurring east of Hamilton after significant snowfall in February 2019. Furthermore, two moose in Idaho suffered fatal outcomes in 2022 and 2023 following ingestion of Japanese Yew. While white-tailed deer appear to be largely unaffected, mule deer exhibit susceptibility. Humans, pets, and domestic livestock can also experience poisoning from this plant.
Japanese Yew is characterized by flat green leaves that are darker on the upper surface compared to the underside, featuring 1 to 1.25-inch long needles that spiral around the stem. Female plants produce bright red berries in late summer and early autumn, while male plants yield flowers that may resemble diminutive Brussels sprouts. All parts of the Japanese Yew are toxic.
The FWP advises homeowners residing in areas frequented by wild ungulates (particularly across much of the Bitterroot Valley) to inspect their properties for the presence of Japanese Yew and to remove it when possible. The plant and its byproducts should be disposed of in landfills or locations inaccessible to wildlife.
Author: Karen Anderson
Karen is the Editor-in-Chief overseeing all news operations at Foxys Publishing Co. She also loves photography and spending time with her dogs.
