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Are America's Greatest Wildlife Migrations Being Sacrificed To Fossil Fuels?

Writer and ecologist Franz Camenzind investigates why some of Greater Yellowstone's biggest wonders are imperiled. Epic Journeys—Views from the Front Lines of America's Greatest Wildlife Migrations

Pronghorn in front of the Tetons: Over millennia pronghorn have moved between summer range in Grand Teton Park and lower-elevations in winter where they can escape deep snow.  With navigational way-finding passed down from mothers to young across generations, the corridors they use pass through mountains, across rivers and openings in topography. If those routes get plugged by human development, migrations can be severely impacted.. Photo by Franz Camenzind
Pronghorn in front of the Tetons: Over millennia pronghorn have moved between summer range in Grand Teton Park and lower-elevations in winter where they can escape deep snow. With navigational way-finding passed down from mothers to young across generations, the corridors they use pass through mountains, across rivers and openings in topography. If those routes get plugged by human development, migrations can be severely impacted.. Photo by Franz Camenzind
EDITOR'S NOTE:
The Greater Yellowstone Ecosystem is home to some of the last epic terrestrial wildlife migrations on earth. They still exist there because landscapes through which their corridors pass are largely unfragmented by human development. Conservation biologists compare them to the cardio-pulmonary systems of the human body. Like the heart pumping blood and nutrients to vital organs and appendages, elk, deer, pronghorn and other species move through the ecosystem imparting benefits to humans and other species, including native vegetation. Like inhaling and exhaling human lungs, herds migrate to the center of the ecosystem in summer and then, when the snow flies, travel hundreds of miles to winter range at lower elevations. These migrations are wonders of nature that have disappeared from most other areas in the Lower 48. This is the first part of an ongoing series titled, Epic Journeys—Views from the Front Lines of America's Greatest Wildlife Migrations that will feature diverse perspectives.

Story by Franz Camenzind
Wildlife Scientist/Conservationist

You know how it feels when your favorite hunting spot is suddenly transformed into an oil and gas field. Or when you’re on an old Bureau of Land Management two-track and a locked gate with a new “No Trespass” sign stops you because the trail happens to cross a swath of private property. 

Such encounters are becoming all too common as the “New West” takes shape across the region. Being denied access to public lands leaves us frustrated at best and at worst, makes us fighting mad. 

Now, think for a minute, how you would feel if your life truly depended upon having that access? 

Today, access obstructed or denied is exactly what’s facing tens of thousands of mule deer and pronghorn antelope throughout the New West. 

Perhaps nowhere is this more acute then in Wyoming where oil and gas leases are being sold at a record pace, where well pads are being scraped clear of all living things and new roads are crisscrossing the once-wild landscape like spider webs. Where pipelines and pump stations are replacing sagebrush and cottonwoods. And where new fenced ranchettes with their associated paraphernalia are popping up like politicians at a Fourth of July picnic. 

Today, a growing portion of Wyoming’s migratory deer and pronghorn are finding it more difficult to access critical winter range—lands vital to their wellbeing if not to their very survival.  These public lands that sustained them for thousands of generations are slowly and methodically being choked off. The Greater Yellowstone Ecosystem holds the most epic wildlife migrations remaining in the Lower 48. If the current trends continue, they will become so fragmented, isolated and transformed as to render them nearly useless for our coveted big game herds. 

We have long known the importance of winter and summer range; now it’s time to recognize the important third element: the migration corridors- the critical threads linking these seasonal habitats. 

If we don’t ensure that these corridors remain intact, continue to support healthy native vegetation and provide unobstructed passage, Wyoming will be on its way to witnessing a drastic and permanent decline in its big game populations. 
"Migrate: to travel seasonally, often between distant and distinct locations and returning, year after year."  —Passage from the book Wild Migrations: Atlas of Wyoming's Ungulates 
That wildlife migrates between habitats to the rhythm of changing seasons is not a recent revelation. It’s been understood since the first hunters entered the region thousands of years ago. That we now know with great precision their locations and the nuances of how migration corridors are utilized is a result of new technologies and good old, on the ground sleuthing. 

Research being carried out by a consortium of agencies, institutions, companies and graduate students, working loosely under the umbrella of the University of Wyoming’s Biodiversity Institute is advancing our knowledge of migrations. Results from this statewide Wyoming Migrations Initiative have made the state a national–if not international leader in big game migration research.

Regionally, the importance of protecting big game migrations can be traced back to the formation of Yellowstone National Park. The park’s original advocates, even in the early 1870s,  recognized that simply encompassing the geothermal features within a relatively small park defined by four straight lines would not guarantee the long-term survival of Yellowstone’s iconic elk herds. They understood that for elk to thrive, the surrounding forests and low elevation foothills and sagebrush plains also needed protecting. 

They may not have discussed migration corridors per se, or grasped the concept of ecosystems, but they understood that the connections between the high country’s summer range and the low country habitat needed safeguards, or the cherished elk herds could be lost. Protection came slowly. An evolving patchwork of conservation law brought much needed protection to the region’s lands, and by default, to the elk migrations that to this day continue to emanate from Yellowstone’s high country. 
Fast-forward, and its today’s pronghorn and mule deer migrations that face challenges, never envisioned a century ago. Their existence is threatened in large part by the rapidly expanding energy industry and its brand of new roads and industrial structures. 

Add to this, the low country’s long established ranches, the recent appearance of hobby ranches, subdivisions and the demands made by mechanized recreationists for more access with fewer restrictions, and it’s clear that the accruements of the New West are creating widespread obstacles to wildlife’s ability to roam freely across their historic and vital lands. 

To better understand the nature of the threats, it helps to understand a bit of wildlife’s history, biology and behavior. Through thousands of years of trial and err, failures and recoveries, the region’s deer and pronghorn populations learned which migration routes worked and which didn’t; which locations and habitats nourished them in summer and which sustained them through the region’s harsh winters- and which didn’t. 

Slowly, over countless generations, these migration patterns became embedded within each herd’s genome. To be sure, not all of Wyoming’s deer and pronghorn make long-distance or even modest migrations. Some, particularly those residing in the lower country spend their years moving about within established home ranges.

Yet we know that hundreds-of-thousands of big game do migrate. The Wyoming Game and Fish estimates that number to be near one million; many follow well-documented routes while other migrations are only broadly known to exist. On-going research will continue to reveal to us what our wildlife populations have known for centuries.

Today, our most precise migration data comes from western Wyoming and the Greater Yellowstone Ecosystem. Data collected from GPS satellite tracking collars placed on hundreds of deer and pronghorn has rendered migration corridor maps with a precision impossible a few decades ago. And with the collars set to record 8 to 10 locations for each animal each day over several years of battery life, researchers are now able to pinpoint the routes used as well as how they spend their time within the corridors.

Thanks to this new technology, migration corridors, some extending over 150 miles have been precisely mapped. 

Beyond providing for safe, secure and unobstructed wildlife movements, functional corridors must also provide forage- trail food for the journey. GPS technology has revealed unique locations, particularly important during spring migration were migrants stopover for days, if not weeks. With follow-up ground-truthing, researchers determined that stopover sites contain abundant and nutrient-rich green-up vegetation vital for replenishing fat reserves lost over winter and to facilitate the migrant’s healthy return to their summer range. 

This new information makes it clear that the migrant’s arrival at and time spent in stopover sites is no coincidence. For these animals to thrive, their migrations must coincide with spring’s green up- with the plant community’s climate-driven phenology. 

Migrations are not happenstance events, they are precise actions honed to perfection over thousands of years. An often forgotten detail is that these animals are not just moving themselves from winter to summer range, but roughly 90 percent of the adult females are also carrying and growing the next generation within their wombs. They are truly walking and eating for two- or three if bearing twins, which can be the case for deer, and more often for pronghorn. 
Pronghorn crossing the Gros Ventre River. Be it pronghorn, deer, elk or other migratory species, they often must find their way through a harrowing gauntlet twice a year. It can include predators, human hunters, busy highways, towns, ranches with barbed wire fences, subdivisions with dogs, avalanches, rivers at flood stage, blizzards and drought, among other things. Photo by Franz Camenzind.
Pronghorn crossing the Gros Ventre River. Be it pronghorn, deer, elk or other migratory species, they often must find their way through a harrowing gauntlet twice a year. It can include predators, human hunters, busy highways, towns, ranches with barbed wire fences, subdivisions with dogs, avalanches, rivers at flood stage, blizzards and drought, among other things. Photo by Franz Camenzind.
Any disruption of timing or denial of access to the nutrient-rich stopover areas can impact the growth of the unborn, jeopardizing their health and survival after birth, which can spell long-term problems for the herd. The newly emerging forage fills this vital need at this critical time. It’s imperative that the migrants be able to surf the green wave with uninterrupted, timely precision. 

The Migration Initiative’s publication Wild Migrations: Atlas of Wyoming’s Ungulates describes the importance of stopovers: “Biologists are now learning that migratory deer, moose, and pronghorn spend as much as 90 percent or more of the spring migration period in stopovers. Less than 10 percent of the migration is spent actually migrating toward summer range.” 

GPS tracking technology has also pinpointed corridor chokepoints or bottlenecks within the corridors, some as narrow as a few yards. Many are natural, geographic features such as streams where cut banks and shallow waters facilitate crossings. Others like the Gros Ventre Valley’s Red Hills bottleneck along the Path of the Pronghorn are defined by landforms. 

The corridor that pronghorn move through is scenically spectacular but also rugged and unforgiving when winter sets in.  Photo by Franz Camenzind
The corridor that pronghorn move through is scenically spectacular but also rugged and unforgiving when winter sets in. Photo by Franz Camenzind
In this case, the corridor extends across a barren and very steep side slope wedged between the Gros Ventre River and the rugged Red Hills above. A route better suited to bighorn sheep then pronghorn. When traversing this section of their path, the pronghorn do so at a slow gate- no stopover here. Other bottlenecks can be man-made: fences, roadways and rural subdivisions, or simple, random human activities. 

Most of these can be mitigated: remove or modify fences, institute seasonal closures, construct highway over- and underpasses and require new residential developments to be wildlife permeable by clustering buildings and prohibiting confining fencing. In most cases common sense compromises exist. It‘s reasonable to ask: why don’t deer and pronghorn just go around obstructions and bottlenecks? 

Researchers have concluded that pronghorn and to an even greater extent, mule deer have developed a strong fidelity to their corridors, the details of which appear to be passed from one generation to the next by the females. This, in conjunction with the need for precise timing seems to leave them with little capacity to adjust to changes within the corridors, particularly those that appear suddenly from one season to the next. 

The most corridor-loyal of Wyoming’s pronghorn appear to be those using the federally protected Path of the Pronghorn between Grand Teton Park and the southern national forest boundary in the Upper Green River Valley. From there, the corridor funnels south through private land and eventually through the historic Trapper’s Point bottleneck west of Pinedale. 

From there, pronghorn often fan out across the BLM lands and Sublette Basin’s sagebrush sea. During the harshest of winters, these pronghorn may once again gather together and move 90 miles farther south to the Rock Springs region where they come nose to fence with the ultimate barricade- the tightly fenced, Interstate-80 human movement corridor.

If overpasses were constructed here, Grand Teton’s pronghorn could complete their historic migration all the way to northeastern Utah: a near 200-mile trek. But here’s the kicker: this Sublette Basin BLM land is home to the Pinedale Anticline (308 sq. mi.) and Jonah (33 sq. mi.) oil and gas fields and the recently permitted 220 square-mile Normally Pressured Lance Gas Project (NPLP). This is a massive complex of energy development that has only come on line in the last 20 years.

Best estimates put the total number of wells drilled thus far at 24,000 with another 3,500 currently permitted for the NPLP. Combined, this constitutes one of the largest and most productive fossil fuel extraction regions in the contiguous United States. For reference, it’s an area larger then Grand Teton Park, summer home for the 350-plus pronghorn for which the Path of the Pronghorn is named. This development zone forms a contiguous 45-mile, north-south industrialized gauntlet through which these antelope must navigate, twice a year, every year—if they are to survive. 
Natural gas drilling pads pepper the Jonah Field and Pinedale Anticline in the southern tier of the Greater Yellowstone Ecosystem, causing severe impacts to migratory wildlife and their ancient corridors. Former Gov. Dave Freudenthal, after once inspecting the Jonah Field and lamenting the destruction of wildlife habitat, called it "an example of what not to do."  Photo courtesy Ecoflight (ecoflight.org)
Natural gas drilling pads pepper the Jonah Field and Pinedale Anticline in the southern tier of the Greater Yellowstone Ecosystem, causing severe impacts to migratory wildlife and their ancient corridors. Former Gov. Dave Freudenthal, after once inspecting the Jonah Field and lamenting the destruction of wildlife habitat, called it "an example of what not to do." Photo courtesy Ecoflight (ecoflight.org)
It should also be noted that the greater Sublette pronghorn herd, of which the Grand Teton pronghorn are a part, has declined nearly 40 percent in the past decade-plus. In February of this year, the Upper Green River Alliance, Western Watersheds Project and Center for Biological Diversity filed a suit in Federal Court to have the BLM’s NPLP final decision reviewed and modified before allowing it to move forward. 

In part, the suit claims the BLM’s Environmental Impact Statement failed to take a “hard look” at the impact this decision will have on the Grand Teton pronghorn population. The contention being that this unique population could be lost when the NPLP, with its permitted 3,500 wells and 277 miles of new road with an anticipated 1,284 daily vehicle trips is fully developed. The underlying question is this: is it right to knowingly jeopardize the survival of a national park species? 

Imagine if you knew that hummingbirds at your backyard feeder were disappearing due to habitat destruction in the neo-tropical zones of Central America thousands of miles away. Or if waterfowl that hunters pursue weren't returning because wetlands in southern climes were being lost or contaminated. Or if fish and sea turtles were vanishing because of obstacles or lethal factors preventing their movement. These, in fact, are major conservation issues.  So again, ask the question: is it right to sanction an activity that knowingly jeopardizes the survival of a beloved species that lives part of the year in a crown jewel national park?
The contention being that this unique population could be lost when the NPLP, with its permitted 3,500 wells and 277 miles of new road with an anticipated 1,284 daily vehicle trips is fully developed. The underlying question is this: is it right to knowingly jeopardize the survival of a national park species? 
The suit also asks the BLM to take a “hard look” at the impacts full development will have on the sage grouse, a candidate for listing under the Endangered Species Act. According to the lawsuit, Wyoming Game and Fish classified 75 square miles of the NPLP gas field as priority habitat: “areas of the highest conservation value for maintaining or increasing sage grouse populations.” 

And within the priority habitat, 42 square miles constitute the state’s only designated sage grouse “winter concentration area” because its abundant sagebrush and traditionally low snow pack attracts an estimated 2,000 additional wintering grouse. These sage grouse may not migrate on delineated flight paths, but how good is a successful migration if the crucial destination is so impacted as to no longer support their numbers? 
A Greater Sage-Grouse hen.  Sage-grouse are important indicators of habitat distrubance threshholds for wildlife and in most of the West, as well as Wyoming which holds the best habitat left, they are in decline.  The BLM has been allowing oil and gas drilling to proceed in sage-grouse habitat. Photo by Franz Camenzind.
A Greater Sage-Grouse hen. Sage-grouse are important indicators of habitat distrubance threshholds for wildlife and in most of the West, as well as Wyoming which holds the best habitat left, they are in decline. The BLM has been allowing oil and gas drilling to proceed in sage-grouse habitat. Photo by Franz Camenzind.
Tragically, these wildlife populations are forced to compete against the estimated $18 billion of fossil fuels buried under the NPLP field alone (with an estimated $1.1 billion in royalty payments expected to flow into Wyoming’s energy-dependent budget). Sage grouse may be hardy flyers, and pronghorn the fastest North American land animal, but they will be hard pressed to outpace $18 billion of industrial competition. 

According to a February 20,  2020 Jackson Hole Daily article, part of the BLM’s reply to the concerns outlined within the law suit was, “that they would do studies concurrent with development, because they weren’t sure what the impacts would be.” Scientists said this is tantamount to forcing a loved one to undergo major surgery uncertain of the side effects or the outcome, but reconciling the action with a promise that concurrent studies will be conducted. 

Are the pronghorn and sage grouse to take solace in knowing that in a decade or so a report may be released clarifying why the patient will not fully recover, or will survive only at a fraction of its former capacity—if it survives at all? The BLM tends to paint an unrealistically rosy picture of the impacts energy development has on mule deer. For example, a 2019 lease sale notice stated that 75 percent of the well-defined Sublette mule deer migration corridor would be protected with a no surface occupancy restriction, i.e. drilling would not occur right on top of the corridor itself.

Knowing what we know now about the nuances of a successful migration corridor, it’s quite obvious that protecting 75 percent of the corridor will not be 100 percent effective. That’s like saying that a bridge that is 75 percent structurally complete is 100 percent safe to drive over. 

Energy company officials often argue that less than five percent of a developed lease is actually disturbed, implying that that cannot equate to a serious impact to anything. The unequivocal response comes from a 17-year mule deer study (two years predevelopment and 15 years through development) carried out by Hal Sawyer and colleagues in Wyoming’s Green River Basin. It brought to light new details of how mule deer respond to development. 

A mule deer doe with a GPS collar.  She is helping researchers develop new maps to show where wildlife goes and the habitat it needs. Photo by Franz Camenzind
A mule deer doe with a GPS collar. She is helping researchers develop new maps to show where wildlife goes and the habitat it needs. Photo by Franz Camenzind
The authors concluded: “Mule deer consistently avoided energy infrastructure through the 15-year period of development and used habitats that were an average of 913 m [0.56 mile] further from well pads compared with predevelopment patterns of habitat use.” 

The math completes the story; with this data, every well pad causes roughly a square mile of habitat to be lost to, or significantly underutilized by mule deer. And if a well pad’s impact area includes a migration corridor, its functionality may also be compromised, if not lost outright. In spite of the on the ground mitigations already in place, including directional drilling, drilling multiple wells from single, but larger pads, and a recent 45 percent reduction in hunter harvest, the study area’s deer population decreased 36 percent during the study period. 

Over the past three decades, the greater Sublette mule deer population, of which the study area animals are a part, declined by 40 percent. During the same period, the state’s entire mule deer population experienced a 31 percent drop. The ability of mule deer to adjust to disturbances of this magnitude will be slow at best–if it occurs at all. 
Over the past three decades, the greater Sublette mule deer population, of which the study area animals are a part, declined by 40 percent. During the same period, the state’s entire mule deer population experienced a 31 percent drop. The ability of mule deer to adjust to disturbances of this magnitude will be slow at best–if it occurs at all.
The Sawyer study concluded that “minimizing impacts through onsite mitigation…may not be possible. Onsite mitigation [on the Pinedale Anticline] was insufficient to abate behavioral and demographic consequences to mule deer during our study.” What then is the future for Wyoming’s mule deer- a species already facing the unknowns of climate change and suffering the devastating impacts of Chronic Wasting Disease

The  reality is clear; current mitigation practices, even if expanded will not eliminate the impacts to the region’s mule deer. The explosive rate of energy extraction is creating a new and much diminished normal for deer herds. How will this impact Wyoming’s hunting community and the Game and Fish, whose budget depends heavily upon license sales? 

And what of the question rarely addressed during the lease sale and permitting process; how will these declines impact the larger Greater Yellowstone Ecosystem of which these populations are an integral component? Data indicates that it will be significant, but how significant, only time will tell.

The New West, with all its operations and paraphernalia is overtaking the public landscape and displacing its wildlife. We are the source of the problem: constructing countless obstacles, expanding our recreational activities, altering the climate, which in turn impacts plant diversity and phenology. The only response our pronghorn, deer and grouse have is to find a way to survive with far fewer numbers on greatly impacted habitat. 

Little thought is given to the long-term, socio-economic consequences of this New West reality. It is we humans, the most aware and adaptable species planet earth has ever known that should modify behaviors and make the compromises. The burden of our excesses should not be born by the innocents. We have many currencies with which to barter, wildlife has but one: their lives. 
Little thought is given to the long-term, socio-economic consequences of this New West reality. It is we humans, the most aware and adaptable species planet earth has ever known that should modify behaviors and make the compromises. The burden of our excesses should not be born by the innocents. We have many currencies with which to barter, wildlife has but one: their lives. 
As we celebrate the success of protecting a few migration corridors, we must not allow ourselves to become lulled into thinking that all is well on the western front–for it is not. We must ensure that the public lands beyond the corridors are not suddenly opened to all sorts of environmental mischief.

These lands are not vacant of life; they are home to a myriad of sagebrush steppe denizens that do not migrate: jackrabbits, cottontails, prairie dogs, Ferruginous hawks, golden eagles, chipmunks, sagebrush lizards and deer mice- to name but a few. Plus, these lands are the family rearing home for dozens of songbird species that do migrate, but often under the public’s radar. And, not to be forgotten, are the mule deer and pronghorn that do not migrate—the year-round residents of the Wyoming’s sagebrush country. Their land and their lives matter too. 

Any migration corridor victory should not be marred by the neglect of the land beyond. It too is a critical component of the greater ecosystem. The Greater Yellowstone Ecosystem is more then a park surrounded by majestic wildlands; it’s the largest example of its kind remaining on the planet. And to the credit of our conservation predecessors, it remains home to nearly all of its original inhabitants as well as its many natural processes, including the important long distance migrations of thousands of deer and pronghorn. 
A band of pronghorn move across the Red Hills in the Gros Ventre Mountains east of Jackson Hole on their journey between Grand Teton National Park and the Upper Green River Basin. Photo by Franz Camenzind
A band of pronghorn move across the Red Hills in the Gros Ventre Mountains east of Jackson Hole on their journey between Grand Teton National Park and the Upper Green River Basin. Photo by Franz Camenzind
Today, like many of our natural treasures, the Greater Yellowstone Ecosystem is under attack. The parks are at or near visitor capacity. The land beyond is being developed, fragmented, drilled into, dug up, and whittled away by a thousand actions that individually may appear to some as inconsequential, even tolerable. What is not inconsequential and not tolerable is the well-documented, concurrent decline of many of our wildlife populations. This is not a coincidence. 

Although the parks and the low country sagebrush sea are many miles apart, and appear dramatically different, it is clear that what happens to the low country pulses through the greater ecosystem. There can be nothing more illustrative of this then witnessing a line of pronghorn moving with determination across the flanks of the Red Hills. No image is more telling then that of scores of mule deer jostling to cross the New Fork on their way to their Hoback summer range. 

Satellites images aren’t needed to interpret the story told by the endless line of hoof prints imbedded in the snow or etched into the ground of the Upper Green. The Yellowstone migrations: life coursing through the greater ecosystem on pathways thousands of years old. Keeping the pathways open is our responsibility—it must not become our failing.
Franz Camenzind
About Franz Camenzind

Writer Franz Camenzind, a longtime resident of Jackson, Wyoming, has a diverse background. He is the son of dairy farmers in Wisconsin and not long ago was honored as a distinguished science alumnus at the University of Wisconsin-Stevens Point. A biological field researcher by training, he earned his PhD from the University of Wyoming. He is known for helping to pioneer new appreciation for the social dynamics of canids, namely coyotes. Camenzind is an award-winning wildlife cinematographer who worked for companies ranging from BBC to National Geographic, including a project in which he was the first to film pandas in the wild. During his tenure as a professional conservation advocate, he served as executive director of the Jackson Hole Conservation Alliance and, earlier, he was a founding member of the Greater Yellowstone Coalition. In addition, Camenzind writes a column, Wild Ideas, for Mountain Journal.
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