The Bitterroot Valley of Montana has been the site of a large number of wildlife malformations and declines since the early 1990s, along with most of the Western United states. These have included moose, elk, bighorn sheep, white tailed deer, birds, and rodents. A study of genital malformations conducted from 1996 to 2000 showed that as many as 67% of male deer studied had genital malformations. These abnormalities included “varying degrees of apparent genital developmental anomalies, specifically misaligned and undersized scrota and ectopic testes” This study was conducted using road killed animals in the Bitterroot valley of Montana.

Because several pesticides have been shown to induce these kinds of malformations, like malformations at the Hanford site in Washington, and Malhuer National wildlife refuge in Oregon, pesticides were looked at as a possible cause. In 2008 a risk assessment of the Bitterroot Valley was conducted and pesticides were found to be present in the environment, including pesticides like Chlorothalonil that are not used in the Valley but are carried over the Bitterroot mountains from potato fields in Idaho. This demonstrates that these chemicals can travel long distances from their sources. Of greater interest because of the frequency of malformations found specifically in road killed animals is the spraying of road sides across the West, like is seen on Utah’s highway 39, is the use of pesticides along roadsides and other right of ways. Like in Utah and other Western states Montana uses large amounts of pesticides on its road ways and other right of ways including the herbicide Glyphosate(2). Montana has a Noxious Weed Permanent Trust Fund that grew from $1 million in 1987 to $10 million 2007 (1).  Weed control efforts are not limited to road sides but include, Rail road right of ways, power line right of ways, pipe line right of ways, trails, and wildlife management areas, administered by both public and private entities such as The Nature Conservancy, and the Rocky Mountain Elk Foundation. Herbicide use is also extensively used in forestry as well. 

Wildlife in the Bitterroot has been documented to have multiple malformations for the last 20 years, concurrent with declines in these wildlife. These malformations include under bites, testicular malformations, Laminitis, fibromas, and abnormal antlers very similar to what has been seen in Utah, and Alaska, as well as other locations across the western United States. Many of these malformations and conditions are associated with endocrine and metabolism disruption, and in combination point to environmentally induced Diabetes as being a root cause of much of what is seen.

You can read about these under bites here:

You can read more about testicular malformations:

The North end of the Bitterroot valley is within the Lolo National Forest. In the early 1980s herbicide use ceased in the Lolo National forest for weed control. In 1992 it was brought back, and expanded. This includes the aerial spraying of Picloram, 2,4-D, and Clopyralid.  2,4-D is a known endocrine disruptor.