Backlog of migration: report highlights importance of wildlife corridors |

energy development

Hoofs, such as these spiny horns approaching the Pinedale Anticline natural gas field in the upper Green River Basin, Wyoming, are increasingly confronting oil rigs and other energy development activities in their habitat.

Deer, elk and hornbills in the western United States can travel long distances across rugged country every spring and fall to find the best food available to ensure their survival.

Until the advent of the more affordable GPS collars and mapping technology, the extent of those movements was unknown. However, research has “thriving” in the past decade, providing the public with an excellent opportunity to conserve and protect roads, and therefore animals, according to Matt Scruch.

Scrush is director of the US Public Lands and Rivers Conservation Project at the nonprofit Pew Charitable Trusts, a “change agent” for global research and public policy. He and Leslie Duncan recently co-authored a report that brought together many Key Studies on Wildlife Migration, while noting the implications of working as a means of promoting conservation. The article is titled: “How to Conserve Wildlife Migration in the West.”

“The report is really a call to action,” Scruch said in a phone interview. “It’s a call to use the latest and greatest scientific insights to conserve these incredibly important wildlife populations for the future.”

Some of the barriers to migration the report highlights include: urban sprawl, highways, fencing, mining, and oil and gas exploration. “An estimated 620,000 miles of fence run through the western United States, much of it in wildlife habitats away from population centers,” the report noted.

elk crossing

Wildlife and vehicle collisions pose serious risks to motorists and ungulates, such as those elk crossing US Highway 89 north of Jackson, Wyoming, during their spring migration.


As states like Montana continue to see population growth, Scruch said, wildlife problems will only increase. He cited the growth of rural housing as an example of how traditional wildlife habitats are being fragmented. Montana communities with growing populations include Bozeman, Big Sky, and Livingston that lie on the edge of the Greater Yellowstone ecosystem, one of the safest wildlife sectors in the United States.

“There are more people living in Montana than there are in the state’s history,” Scruch said. “There are more cars on the road, more homes in suburban frontage and more pressure on these wildlife populations.”

Much of the research mentioned in the Pew report occurred in studies conducted through the University of Wyoming’s Immigration Initiative. Program researchers have identified the long migration routes of mule deer, antlers, and elk in the western third of the state. The motion diagram showed the importance of the general mountain lands as a source of nutrition while the lowlands are central to the winter range.

“Conservation of a particular immigration may include a bridge across a highway, an exclusion zone for new energy development, and a county land use plan that includes wildlife movement areas,” Scruch and Duncan said. “The science is clear and the solutions are there. All that remains is for the various stakeholders to embrace these solutions.”

While wildlife studies may be well known regionally or in biology circles, Skroch and Duncan have condensed the highlights of the research—along with potential challenges and solutions—into one easily digestible package for a larger audience. Scrush hopes that agency officials and lawmakers, who are in a position to establish “good public policy,” will read the document.

For those involved in financial terms, the report also noted the potential economic impacts.

“Detailed evaluations of the recent economic impact of ungulate migration are scarce,” the report said. “But one analysis of 2015 data from Wyoming found that the state’s large game types, most of them immigrant, support $224 million in retail sales, have a total economic impact of more than $303 million, and support at least 3,100 jobs, especially mentors who host Poachers from outside the state. Hunting and equipment provide significant economic benefits to other Western countries. For example, during 2014, elk hunters spent $138 million on food, housing, transportation, and equipment in Montana.”

immigration movement

It is unusual to see thistles in woods or wooded areas. They are only found in places like this during migration.


After scanning the Pew report, Justin Good said the studies were all familiar but the report’s tone of “a sense of crisis” did not apply to Montana. Judd oversees wildlife studies in the state as chief of the Office of Wildlife Research and Technical Services for the Montana Department of Fish, Wildlife and Parks.

In Big Sky State, Goode said wildlife movements are not unnecessarily hampered. In places where GPS wildlife has identified fences that prevent travel, the agency has successfully worked with nonprofit organizations, landowners, the state, the Forest Service, and the Bureau of Land Management to make the fences wildlife friendly.

“We’ve been working together on these things for a long time,” he said.

This is the final year of a three-year, spiny-horned tracking project in eastern Montana. Judd said about 700 spiny horns were hunted in eight study areas with 400 still transmitting data. So far, hoops have revealed that most animals in eastern Montana move around a lot in search of the best food but don’t migrate.

Meanwhile, in western Montana, a herd of thistles migrate annually through the Big Hole Valley to reach their winter range south of the Pioneer Mountains. In the summer, Judd said, the animals are close to the anaconda and the Mount Hagin Wildlife Management Area.

Several hundred elk are also surrounded. One bull walked from Broadus to the Black Hills of South Dakota and stayed. Judd said an elk from Ashland almost walked to Ikalaka but returned home.

As Scruch pointed out, there is something about the idea of ​​wildlife migrations that sparks interest among people.


A recent study, conducted over a 14-year period, found that mule deer halted their migration in Wyoming when they encountered rigs.


In south-central Montana, FWP wildlife biologist Sean Stewart tracks about 60 hunted mule deer in three winter range areas near Belfry Grounds. The idea was to consider potential transmission pathways for chronic wasting disease, which was first discovered in a mule deer shot in the area.

The study so far has shown that most deer are moving northwest to Red Lodge Creek and Cooney Reservoir, and not into the mountains or south into Wyoming as Stewart thought they would.

“I never expected that,” Stewart said.

He added that the observation highlighted the importance of the dry land with sagebrush trees at the base of the Berthoth Mountains for wintering deer. It also underscores the ability of chronic wasting disease to be transmitted throughout the region, although it has not yet been detected in deer in the far north.

Whether due to disease, drought or habitat loss, Stewart said, mule deer numbers have been in slow decline across the Beartooth Face. During his last survey, mule deer numbers along the Stillwater and Clarks Fork Rivers of the Yellowstone River were at their lowest point in the 40 years he took the census.

“Upper Stillwater has always been our breadbasket for mule deer,” he said.

Stewart noted that as deer numbers declined, and public access was restricted, so did the use of hunters in the area. Meanwhile, elk populations continue to rise in hunting grounds 575 and 502, about 2,600 animals – the highest ever counted.

elk migrations

Elk make their way along a mountainside into the Greater Yellowstone ecosystem. Nine herds using the area migrate 30 to 100 miles from valley lowlands to high meadows in summer in search of green forage.


The Pew report also notes that climate change and increased recreational use of public lands pose threats to wildlife.

“One of the primary ways climate change may affect migratory ungulates is by shortening growing seasons and increasing the frequency and severity of droughts, which may reduce the forage that animals reach along their migration routes. These effects may reduce the foraging benefits of migration to the point that animals Either you will experience increased mortality and decreased reproduction or choose to reside year-round rather than migrate.

The recreational use of public lands covers a wide range of activities.

“Mountain biking; use of e-bikes, ATVs, and motorcycles; cross-country skiing and snowboarding; mountain climbing; camping distractions and other activities are growing in popularity.” “Existing lane systems are receiving more use, and new lane systems are rapidly expanding into areas that have historically had low levels of human use. The potential impacts of these increased recreational demands on migratory animals on public lands, including potential displacement, increased energy expenditure, and reduced Reproduction rates, are not yet well understood.”

The lengthy report, highlighted with footnotes to several wildlife studies, and outlining looming threats as well as possible solutions, can be found online at:

“We have the science and the data to inform the right response to these threats,” Scruch said.

Leave a Comment