American Conifer Society<\/a>, they can grow anywhere from three to 120 feet tall and their trunks can reach up to 12 feet in diameter. They can be short and bushy or more lofty and sparse, depending on the species. Most yews have red bark and springy wood that\u2019s been extremely popular for longbows for centuries. <\/p>\nIn fact, William Shakespeare dubbed yew \u201cdouble-fatal\u201d in his play \u201cRichard II\u201d because of its poisonous qualities and its usefulness for bows, IDFG lead botanist Lynn Kinter tells Outdoor Life<\/em>. The historic references don\u2019t stop there.<\/p>\n\u201cIn 55 B.C., Julius Caesar wrote a book called Commentary on the Gaelic Wars<\/em>. He described a king being overrun in battle, and rather than being killed by the enemy, the king drank yew extract to commit suicide,\u201d Kinter says. \u201cThree of Shakespeare\u2019s plays talk about yew being poisonous. In \u2018Macbeth\u2019 when he says \u2018double, double, toil and trouble, fire burn and cauldron bubble\u2019? Well further down in that verse, he talks about \u2018gall of goat and slips of yew\u2019.\u201d<\/p>\n![\"japanese](\"https:\/\/www.outdoorlife.com\/uploads\/2023\/02\/10\/japanese_yew_pacific_yew.jpg\")
(Left) Japanese yew is an extremely toxic variety of exotic yew. (Right) Pacific, or Western, yew grows along rivers and is native to the Idaho. It\u2019s not nearly as toxic as other varieties. troyka \/ Adobe Stock \/ Jason Hollinger \/ Wikimedia Commons<\/i><\/figcaption><\/figure>\nA few yew varieties are native to North America, and those species are less toxic than exotic ones. These include the Pacific, or western yew, and the Canada yew. But in population centers, exotic varietals like Japanese and European yew are far more popular for ornamental landscaping. They\u2019re also way more deadly to anyone who takes a bite.<\/p>\n
How Does Yew Kill Wildlife? <\/h2>\n
Last year, Idaho\u2019s Wood River Valley saw a massive elk die-off at the hands of the conifer.<\/p>\n
\u201cWe actually quit counting at about 20, because it wasn\u2019t about a body count, it was about determining what was killing so many elk,\u201d Thompson, who works from the IDFG Magic Valley regional office, says. \u201cYew has been killing wildlife in Idaho for many years. This is not an issue that\u2019s unique to the Wood River Valley, and it is not specific to wildlife. It will kill anything that eats it. Pets, wildlife, people\u2026it\u2019s extremely toxic and it happens very fast.\u201d<\/p>\n![\"pronghorn](\"https:\/\/www.outdoorlife.com\/uploads\/2023\/02\/10\/pronghorn-killed-by-yew-in-Payette-17Jan2017a-Mark-Sands-IDFG-photo.jpg\")
A herd of pronghorn died from yew poisoning near Payette, Idaho in January 2017. Used with permission of Idaho Department of Fish and Game<\/i><\/figcaption><\/figure>\nAll parts of the yew tree contain alkaloids. These are organic compounds that occur naturally in plants and have physiological and psychological effects on humans and animals. Morphine is an alkaloid. So is the nicotine in cigarettes, the caffeine in coffee, and the quinine in a gin and tonic. The alkaloids in yew are called \u201ctaxines,\u201d and they\u2019re toxic to the cardiovascular system.<\/p>\n
\u201cToxic alkaloids cause breathing difficulties and then heart failure. It actually acts on various channels within the cells of the heart,\u201d Kinter explains. \u201cIt doesn\u2019t take very much. Less than 1 percent of the bodyweight can cause death. For a small elk, that would translate to about a cup of leaves, or 50 grams.\u201d<\/p>\n
Can You Prevent Yew Poisoning?<\/h2>\n
One of the trickiest parts of preventing yew poisoning in wildlife is catching it before it becomes fatal. <\/p>\n
\u201cIn wildlife, the first symptom of yew poisoning is usually death,\u201d Kinter says. <\/p>\n
When IDFG gets a report of dead elk, biologists first look at body condition, wildlife health program coordinator Stacey Dewaulter tells Outdoor Life<\/em>. If the animal seems otherwise healthy, a necropsy often reveals yew in the digestive system. <\/p>\n\u201cWe\u2019re really concerned when we see animals in pretty good body condition that are found dead. We tend to think \u2018what\u2019s killed them quickly?’\u201d Dewaulter says. \u201cTypically, if it\u2019s near neighborhoods or houses with ornamental plants, our biologists will cut them open to see if there\u2019s yew in the digestive tract. The animals usually die quick enough that the yew is not digested and it\u2019s easily identifiable.\u201d<\/p>\n![\"pronghorn](\"https:\/\/www.outdoorlife.com\/uploads\/2023\/02\/10\/pronghorn-killed-by-yew-in-Payette-17Jan2017b-Mark-Sands-IDFG-photo.jpg\")
Otherwise-healthy wildlife might exhibit less obvious signs of stress, like this pronghorn that died in the Payette incident. Used with permission of Idaho Department of Fish and Game<\/i><\/figcaption><\/figure>\nThe one easy part of diagnosing a yew death is that the victim can\u2019t get far from the source before expiring. <\/p>\n
\u201cOnce you start finding animals that died from it, the yew is typically in very close proximity,\u201d Thompson says. \u201cWe\u2019ve had situations where animals died in the cemeteries where they found the yew. Usually their gut is full of yew but there\u2019s also yew needles in their mouth, in their esophagus, so it\u2019s pretty fast-acting.\u201d<\/p>\n
Why Is Yew So Popular?<\/h2>\n
The tree has been a heavy hitter in the horticulture sphere for about a century, Kinter says. <\/p>\n
\u201cThey\u2019re a medium-water-use species, they\u2019re cold tolerant, they can survive the heat in the summer, they can grow in a variety of soils, so they\u2019re really versatile in terms of where they can go,\u201d Kintner explains. \u201cThey\u2019re also easy to prune, you can go chop on them at any time of year and they do fine. They look good, and there are lots of different varieties. You can get small ones, tall ones, from compact shrubs to fairly tall trees.\u201d<\/p>\n
What\u2019s The Solution?<\/h2>\n
The city of Ketchum and Blaine County are leading the charge on educating the public about the dangers of growing ornamental yew. But according to Thompson, they still have a long way to go.<\/p>\n
\u201cWhen we put this stuff out on social media, people say \u2018why do people continue to bring it in?\u2019 But [most of] the plants we\u2019re finding are mature, so they\u2019ve been in the ground for a long time,\u201d he says. \u201cWe did find some new plantings, so there is still an educational component that landscape companies and homeowners need to understand so that they\u2019re not going to another community outside of Blaine County, buying the yew, and bringing it back.\u201d<\/p>\n![\"elk](\"https:\/\/www.outdoorlife.com\/uploads\/2023\/02\/10\/Idaho-Fish-and-Game-officer-after-loading-a-moose-that-had-died-after-eating-yew-north-of-Ketchum-January-2023-1.jpg\")
An Idaho Fish and Game officer loads a yew-poisoned elk near Ketchum in January 2023. Used with permission of Idaho Department of Fish and Game<\/i><\/figcaption><\/figure>\nWhile the yew trees themselves are the most obvious culprit, Thompson explains the problem results from multiple compounding factors. <\/p>\n
\u201cWe have large elk and deer populations that are resident, they are not migrating in and out of the valley. We have a larger population base than we\u2019ve had, which is building out on traditional winter range. Our elk herd that lives between Hailey and Ketchum never leaves private property, and it\u2019s a growing herd because there\u2019s never any hunting pressure,\u201d he says. \u201cSo it\u2019s kind of that perfect storm.\u201d<\/p>\n<\/p><\/div>\n