• BOOKS ABOUT WILDLIFE AND HEALTH

  • My latest book NOW AVAILABLE

  • Available from Amazon paperback or Kindle

  • Updated w/double blind study results. Ebook or paperback

  • New updated edition available NOW!

  • Recent Posts

  • Tracking Footprints

  • Archives

  • Top Posts

  • Pages

Part V – What’s Next for Bighorn Sheep

The vista from one sky island to another

Disease, domestic sheep proximity,  habitat degradation, human encroachment, water construction, predation—all part of the tangled web of problems for bighorns. But there are still other pressing problems for these animals that may have deeper consequences.

A big stumbling block biologists are facing is connectivity. Sky Islands and basin/range topography are comprised of isolated islands of habitat. Minimal population size for healthy genetic diversity seems to be around 200 animals to ward off most stressors. Historically, desert bighorns existed as metapopulations, large areas of basin/range where bighorns could roam and connect freely. A bighorn population wasn’t just one mountain top, but a wide swath of desert and mountains containing sub-populations inside of metapopulations. Harley Shaw commented to me that in looking at the history of desert bighorns in the Southwest, his view was that historically mountain ranges with these small populations were constantly winking out. Roaming instincts would push a few bighorns across desert floors to repopulate new ranges. Today that’s a near impossibility.

The entire state of Nevada alone was once considered one large population of bighorn sheep. “Moisture is so spotty, and we have so many rain shadows,” Mike Cox from Nevada Department of Wildlife relates, “that bighorns were very nomadic. They would chase green-up.”

I asked Cox about connectivity today . “It’s pretty sad, especially in Clark County which is the county of Las Vegas. We have islands, these sky islands of bighorn sheep that can’t go anywhere. They can’t roam. They can’t go on forays or they’ll get killed on 6 or 8 lane highways.”

Along with roads and barriers, there is the issue of a roaming bighorns coming into contact with domestic livestock and disease. Without a viable solution, many wildlife agencies resort to  periodic infusions of additional bighorns on a mountain. With new knowledge of disease strains, even that has its limitations. Amber Munig with AZGF told me the agency was looking at boosting a bighorn population southwest of the Colorado River. They tested both herds and although both have titers for Mycoplasma ovipneumoniae, the strains were different so they cancelled the translocation.

“Our translocation program is slower now because we don’t have as many areas to put them into and we’re very cautious about moving pathogens from one population to another,” Munig says. “We’re mostly supplementing existing populations at this point in time to ensure the genetics is still there and that becomes a concern when you have fragmentation, especially with roads that don’t allow them to cross between mountain ranges.”

Mike Cox is looking towards another answer. Some of the new research points to chronic asymptomatic disease shedders as the reason why a herd just cannot recover. The newest push is to find these shedders and kill them, called “test and remove.” Experiments in Oregon’s Hells Canyon by researcher Francis Cassirer shows promising results with a natural fade-out of the disease over time when carriers were removed in connected populations. But, as Cox points out to me again, “just because one bighorn gets one Mycoplasma strain doesn’t mean the next strain that comes along won’t be worse. There is no immunity that’s generated from one to the other.”

Hells Canyon Test and Remove update 2020. Presentation WSWG Disease Mgmt Venture by Francis Cassirer

Jessica Moreno with the Coalition for Sonoran Desert Protection looks to wildlife linkages as a viable solution for healthy wildlife. Focusing mainly on Pima County around the Greater Tucson area, the Coalition partnered with Arizona Department of Transportation and others to plan a wildlife crossing. The crossing, one under and another over State Route 77, were installed simultaneous with the final bighorn translocation into the Catalinas in 2016. This first of several planned crossings connects the Catalinas to the Tortolita mountains. The next crossing is planned for Interstate 10, a more challenging endeavor, that would continue the wildlife passage from the Tortolitas to the Tucsons, the Silverbells, and through Saguaro National Park West into open desert country and Tohono O’odham Nation Reservation.

Moreno’s viewpoint is that bighorns face a tangled web of stressors, and many we might not even understand or recognize as stressors. But if we look at the bigger picture, giving the bighorns roam to connect, even if one population crashes, more bighorn sheep will come in to boost the population.

“By taking that landscape approach, you allow the animals the freedom to respond to stressors on their own, leaving that option available so they can respond to fire, disease or climate change. Their populations can crash but then rebound the way they need to. I like that about the work I’m doing to establish wildlife corridors and build wildlife crossings as it reaches across different species and gives a little bit more resilience to those populations that are dealing with different pressures.”

So far, with trail cameras placed in the area, State Route 77 crossing hasn’t produced any bighorn sheep using it over the last four years. But it still can be considered successful, with over 5,000 mule deer using it, along with javelinas, bobcats, coyotes, and lots of smaller species. But crossings elsewhere have been successful for bighorns. Wildlife crossings installed between Kingman and the Nevada state line on U.S. 93 between 2007 and 2011 documented use in the first four years by over 6.000 bighorns. Given the complexity of disease issues, it’s hard to know if these kinds of connections might solve the fresh genetic flow yet doom a population to new strains of disease.

The biggest unknown of all is our rapidly changing climate. Connective corridors undoubtedly help facilitate movement, allowing wildlife to adjust to habitat changes and water availability as their environment heats up. The totality of all the issues affecting bighorn sheep in particular is complicated and nuanced. Connective corridors might solve one piece of their Gordian knot but certainly not all.

____________

I made a pie chart of all the desert bighorn sheep stressors I’ve learned about

I grab my snowshoes, prepare a few snacks, and head up to a high mesa locals call Little Bald Ridge. In deep snow it’s difficult to follow the spines of the lower ravines that lead to the mountain top and the animal trail that hugs the hillside higher up would be obscured. But we’ve had little snow this winter and today with a clear sky, a light wind, and temperatures in the teens, it should only take an hour to climb to the wide butte.

I’m hoping to see our little band of Rocky Mountain Bighorn Sheep. They like the wind-swept meadows and craggy overlooks. The elk covet the area too, though the two species never group up. Wolves might be there, but their interest is in the scent of the elk, not the bighorns.

The final ascent leaves me a bit winded. The trees have disappeared. I always have to remember to watch for a large sinkhole beside the animal trail, which the trail swings directly alongside. The elk have trodden down the snow by its edges, but the hole is steep and deep and makes me nervous. I climb the last few hundred yards to the meadow expanse. The ground is cropped clean from the large elk herds who take advantage of this high windy spot that sweeps the snow clear. Even the sagebrush is just bare stems. As I clear the rise, I spot the bighorns. A small herd of ewes and lambs clasp the rocky cliff edges along the eastern rim. The meadows stretch to the west in a large expanse. Picking up my binoculars, I see a mixed age group of rams grazing in a hollow below.

I’ve been here before in winter without seeing bighorns or elk. The wind is usually in a howl, which highlights those moments of deep terrestrial loneliness. Without the bighorns, this top-of-the-world is not right. It’s definitely special to see the bighorns here today. Even so, these small groupings evoke both elation and sadness. I know that on these same ridges just a few hundred years ago, the native peoples who lived in these mountains watched herds of hundreds, perhaps thousands, of bighorns. These ones today are the hanger-oners, the bighorn sheep that survived the onslaught of white men and their livestock diseases. They are the toughest, yet they eye me with sweet docility, unafraid of my presence. I sit down a few hundred yards away and enjoy. Soon they pay me no mind, and go about their browsing business.

Bighorn sheep appear tough because of the rugged places they live, yet in reality they are soft creatures, whether we are speaking of their animal nature or their constitution. Just being with them I feel softer. I’d like my grandchildren to be able to experience their soft-tough nature. The fact that their presence on this planet coincides with ours implies we must care about their plight, not let it extinguish. That forces us to answer difficult ethical and moral questions. First, there is the money that supports these herculean efforts to help bighorns. Where does it come from? We’re talking about millions of dollars. All the western Fish and Game Agency bighorn sheep programs obtain one-quarter of their revenues from bighorn hunting licenses sold to the general public. The other three-quarters comes from Governor’s auctions and raffles. Kevin Hurley of the Wild Sheep Foundation gives me an example.

“In South Dakota, by statute, there are only two bighorn sheep licenses and they are resident only. That generates $550 a year in revenue. The first year they had [a governor’s tag], it sold for $102,000, and 100% of it went back to South Dakota Game, Fish and Parks. So for $102,000 think what can you do for bighorn sheep versus $550.”

Very few bighorn hunting tags are sold per state every year. The situation with bighorns is just too precarious. What supports bighorn sheep programs are these tags that are up for bid at auctions, bought by the super wealthy.  For instance, Rick Smith, a retired telecommunications executive from Dallas, was the highest bidder in New Mexico’s auction and won seven tags over eight consecutive years to hunt bighorn sheep. He spent over $1 million dollars on those tags, 90% of which goes directly to New Mexico Game and Fish’s bighorn sheep enhancement program.

A skylining bighorn ewe

If we value bighorn sheep then there needs to be a way to fund programs that support bighorns other than through hunts and super tags. There is something obscene in the sole financial support to save bighorns throughout the West—native wildlife which are in the public trust—relying on a sliver of mega-rich trophy hunters. Additionally, being dependent exclusively on hunters for bighorn dollars creates a vicious cycle that pressures agencies to put more bighorns on every mountain so as to increase revenue. It also fuels extreme predator management programs like in New Mexico, where the culling of lions never ends despite bighorn herds that are thriving.

Funding is only one aspect. I think we have to be honest—the intensity of life-support programs that especially desert bighorn sheep need may soon be beyond justification. We need to ask ourselves the hard questions. Can we continue to transport water, not only because of the price tag, but as water itself becomes more precious in a thirsty Southwest, will the program even be sustainable. With the extreme drought conditions of 2020, Arizona hauled close to one million gallons of water, some even by helicopter.

Mycoplasma ovipneumoniae is here for the long run. Researchers are still puzzled how to control it and how to deal with emerging new strains. If we support separation of bighorns from domestic sheep and goats, are we willing to boycott wool from Western growers? Or to contribute cash to buy out wool growers and their public lands grazing allotments? While Bighorn Sheep NGO’s have already been actively raising dollars to help retire grazing allotments, isn’t this the responsibility of all Americans? Again, wildlife are in the public trust, therefor all of our responsibility.

It’s obviously absurd and expensive to keep plopping new bighorn sheep recruits into mountain ranges to enhance their gene flow. Should we instead adopt the “test and remove” program, where shedders are identified and culled? Do we give this kind of program a cut-off limit?

There is a point sometime in the future where we’ll have to cut bighorns loose. Yet we do have an obligation to the bighorns to do our best for them, to right so many of the wrongs they’ve suffered from our misdeeds. In my mind, perhaps our best is displayed in places like the Desert National Wildlife Refuge in Nevada or San Andres National Wildlife Refuge—immense tracts of mountain ranges surrounded by even larger tracts of wild areas completely off-limits to the public and livestock. Allow the bighorn populations to fluctuate naturally.

Instead of trying to fill every historically occupied mountain with bighorn sheep, we should consider a sub-population model, where suitable habitat can provide the bighorn sheep natural connective corridors to other nearby ranges. Land might need to be purchased to enlarge the protected area and grazing allotments retired. Initial habitat restoration would be completed, then we’d just let bighorns be bighorns, and lions be lions. This would be asking a lot of the general public; we all need to step up, not just hunters and the super-rich who can buy tags. An egalitarian effort is needed; an extreme push, perhaps a sprint rather than a marathon. For the bighorns sake, it’s time to decide if we are all willing to rise up to the task this implies—guardians of the ancient way of life of the bighorn sheep. At the very least, we owe it to the bighorns to take a hard look at ourselves and what we are willing to do.

Part IV – An Unlikely Partnership. Lessons from Tucson

I’m in Tucson for the month to explore the subject of bighorn sheep and visit with relatives. We’re staying in a rental house nestled along the base of the Santa Catalina mountains. In years past, I’ve explored Tucson’s general area, but I’ve never had a prolonged stay within the city proper.

Tucson has a beautiful backdrop. Besides being cradled by the Santa Catalinas, which rise up to 9000 feet, its eastern border is Saguaro National Park East, and its western border is the National Park West. Other smaller sky islands dot Tucson’s surrounding. The foothills of the Catalinas are filled with stately Saguaro cactus, like tall multi-armed soldiers guarding the mountain itself. The main two lane artillery, Catalina Scenic Highway, pushes ever upward through numerous ecosystems, from desert scrub through pine-oak woodlands and finally to Mt. Lemmon and a subalpine forest. The mountain, so close to a city of half a million people, is a playground for cyclists, equestrians, climbers, hikers, ORVer’s, campers and even target practitioners. What stood out for me amidst the beauty of the landscape was the development that’s skyrocketing. Trophy homes and golf courses clasp the edge right up to the public lands. Suburbia surrounds the National Park. The desert floor is a sea of traffic and homes between the surrounding mountain ranges.

Hiking in the Catalinas

Desert bighorn sheep once roamed freely from range to range across the desert floor. Called a metapopulation, this allowed the sheep to search for precious water sources, food, and escape habitat from predators. The Santa Catalinas can only support about 120 bighorns, a tiny population vulnerable to genetic decline, drought, and disease. But with connections to other populations in surrounding ranges, these sheep could exchange genetics, ensuring their survival. Walk-abouts are built into the hard-wiring of bighorn sheep, in particular males, for this very reason.

This scenario was what populated the Sky Islands of southern Arizona for thousands of years with bighorn sheep. Through market hunting, disease from domestic sheep and habitat destruction from livestock, the population decline probably began slowly with the Spanish in the early 1600s, only to fall steeply in the 1800s with the influx of miners and settlers into the area. But bighorns persisted in the Catalinas while other nearby ranges winked out, probably because of the diversity of habitat and how large the range is compared to others.

Some of the Sky Islands surrounding Tucson

Joe Sheeley grew up in Tucson. As a boy, he watched bighorns on the mountains, fascinated with their agility, spryness, and ability to negotiate even the toughest terrain. But by 1996, the Catalina bighorn herd had disappeared. The Arizona Game and Fish was sending biologists to Pusch Ridge, the favorite escape haunts of the sheep, to periodically scout for sheep, yet they always came up empty. New rules were created with the hope if there were sheep they could be protected: No dogs on Pusch Ridge trails; no hiking off-trail during lambing season. Yet no lambs, rams or ewes were ever seen.

Sheeley is the former Arizona Desert Bighorn Sheep Society president. With the influx of new disease science, in hindsight he has his own theory of what happened.

“In the late 1980s a ram made it all the way from the Superstitions to the Catalinas.”

“The Superstitions are east of Phoenix. That’s a long trek,” I commented.

“Those sheep that had been transplanted from the Kofa mountain range to the Canyon Lake Superstition area had yellow ear tags. That’s how we know where he came from. In my opinion, there is no telling what that ram came into contact with in his journey to the Catalinas. I really believe he ran across hobby domestic sheep or goats, and I think that herd got infected with disease and died off very quickly.”

Superstitions to Tucson

In the 1970s and 1980s, game agencies, fueled by money and demand from hunting groups along with the awareness of the steep losses of bighorns across the West, began intensively translocating Rocky Mountain and Desert Bighorns into their once native ranges. Arizona Game and Fish (AZGF) was no exception. Ramping up reintroductions across the state, they had done extensive evaluations of historical ranges, analyzing water availability, quality of habitat, domestic sheep density, human development, expansion and escape potential. They rated ranges on a scale, then came back and looked at even finer details such as vegetation, and diversity of wildlife. Those that rated highest were the first translocations. Although the Catalinas were of highest quality, the mountain was put on the back burner for relocations.

Hintza in the Catalinas

AZGF had been doing relocations in low density population areas where people didn’t care or pay attention to their predator management policies. Clearing lions off of reintroduction areas beforehand wouldn’t fly in the progressive, environmentally-minded city of Tucson. Even the agency’s somewhat scaled-down predator policy for the Kofas would be highly controversial. The agency had to figure out a way to gain the public’s trust in order to put sheep back on the mountain. State game agencies garner their monies from hunting and fishing tags. Their primary support comes from hunters, the culture of game agencies tends to be hunters, and their primary audience is hunters.

Amber Munig of AZGF told me ““[The plan for the Catalinas] was unique because it was next to a large metropolitan area. And we knew there would be a lot of interest in how we would approach it and a lot of controversy in any kind of predation management we were to implement.”

To the agencies credit, they embarked on a bold idea—a working group comprised of a variety of stakeholders. They pledged to abide by the group’s plan, which would be adaptive depending upon if conditions were to change. Four environmental groups opted in, including the Center for Biological Diversity and Sky Island Alliance. On the other side were sportsmen, Arizona Game and Fish, and Arizona Desert Bighorn Sheep Society. Disagreement abounded, but the biggest rift was the mountain lion strategy. As one can imagine, opinions ranged from doing no predator controls to clearing the mountain of lions in advance of translocations.

Reintroductions of bighorn sheep are typically done in three to four rounds of thirty sheep. A small herd of thirty sheep, neophytes to a new habitat, devoid of any resident sheep which can guide them to prime escape habitat, are exceptionally vulnerable to predation. In previous translocations, the AZGF usually took what they considered the safest, and easiest, way to give new introductions a leg up by “pre-treating” the area and raising lion quotas. By using a diverse Advisory Board that had to reach a consensus, a middle ground was guaranteed to be reached.

Every bighorn would be collared instead of the customary one out of every three bighorns. And no lions would be collared. Lions would be pursued and killed only after evidence showed they’d killed a bighorn, and the pursuit was to be cut off after five days. Females with kittens would be off-limits. Mortalities would be identified through the sheep GPS signal and only then would a pursuit be triggered. This was a complete turnabout to the Kofa AZGF plan where every lion in a wide net surrounding the refuge was collared, making tracking and dispatching easy.

The first capture and translocation took place in November of 2013. Thirty-one bighorns, seven rams and twenty-four ewes, were released. The captures came from the Trigo mountains near Yuma and the Plomosas near Quartzite. By the end of March 2014, sixteen sheep were dead, fourteen by lions. Because of the difficult terrain and the policy of no lion collaring, only three lions had been removed. Houndsmen had to run the lion off a kill to identify the offending lion. One lion went down a cliff face, too steep for the dogs to pursue. Some went into developed areas so the chase was called off. Although the local paper had done many stories on the Advisory Group’s plan before the initial translocation, and there had been several public meetings, the steep losses produced a public outcry on all sides. The Game and Fish held a public meeting in the spring. While the previous three meetings were lightly attended, this one was packed, with protesters holding signs outside the meeting hall.

“We went out of the way to make sure the public knew what we were up to,” said Randy Serraglio of the Center for Biological Diversity. “People tend to not pay attention to something like that until there’s a dead lion. Then everybody is keenly interested.”

Mark Hart, public information officer for AZGF, agreed the plan had already been highly publicized.

“We wanted to be transparent. The grand bargain was: Is it worth it to put bighorn sheep back on the mountain to lose some mountain lions. The mountain lion population was, in our estimation, quite healthy. Based on hunt data and field data prior to the project, we estimated 67 mountain lions in that mountain range and the one connected to it by a pass”

My month in Tucson coincided with the worst drought year in decades. Despite the lack of moisture, during my hikes in the Catalinas and surrounding ranges, I still observed coatis, mule deer, cos deer, and javelinas even with the heavy toll of human activity. The AZGF knew there was plenty of sufficient food for lions. Everyone had expected some losses, but losing half the sheep was a shock.

With the GPS collars in place, managers could visualize where the sheep were moving. Sheeley says the first release site was based on his historic observations, but many of the sheep, unfamiliar with the mountain, headed for the high forests. Without clear visibility, good escape habitat, and naivete as to their bearings, they were easy pickings for lions. Luckily, the remaining sheep found the prime habitat of Pusch Ridge. There they thrived. In fact, at least five lambs were born in the spring with the herd stabilizing. No mortalities were observed for the next seven months. The advisory board had stood firm in their consensus on lions, even in the heat of controversy. With the good news, the second release was scheduled for November and another thirty sheep. This time using their generational genetic compass, those sheep headed for their kin right up to Pusch Ridge. Two more releases took place through 2016.

Hart tells me what he felt happened was some of the sheep came from mountain ranges where no lions existed.

“Most of the sheep came from the Yuma area, but one year we did take one-half of the allotment from the Superstition mountains. Those sheep did not fare well. One reason is they did not have prior exposure to pneumonia and a few of them got it and died. You can’t prove this scientifically, but what we felt was also happening was they were not as well adapted to the presence of lions as the Yuma area ones were. So the lions picked off a few.”

By the end of the project, eight lions were taken out over the four years of the relocation project. If there hadn’t been an advisory board representing a wide variety of voices, it’s almost certain AZGF would have resorted to clearing the area of lions before a second release commenced. As of fall 2020, seventy-five bighorns were on the mountain, the predator program retired in 2016. Lamb recruitment is almost 50% (typical is 25%), with many sightings of uncollared rams and ewes, indicating they were born on the mountain. Since the mountain only historically supported about 120 sheep, the Catalina bighorn herd is well on its way to success.

The Catalinas may be a model of how these relocations should be conducted. Game agencies are responsible for managing state wildlife, but wildlife, considered in the “public trust,” means all the public. A working group representing a variety of viewpoints is a good model for all wildlife agencies, especially on contentious topics such as predator management. Arizona Game and Fish should be applauded for going out on a limb and taking the chance. And they abided by the groups recommendations. When circumstances became dicey, they didn’t revert to easy knee-jerk reactions, but stuck to the plan hammered out by the advisory board.

Even so, the future of the Catalina herd is unknown. That herd along with others on isolated ranges in the desert Southwest, face a myriad of problems into the future. One of the biggest unknowns is the consequences bighorns will face with climate change and the drying of the West.

Tucson

Part III – Invasion of the Aliens hits Bighorn Sheep

 “Watch this,” Ron Thompson was driving back to the researchers bungalow when he spotted a half dozen oryx hanging by the side of the road near a fence line. We’d stopped to watch them as they nonchalantly eyed us back . Huge, bulky, like a hefty elk with 40” scimitar-shaped horns, their beautiful and unusual black and white facial pattern reminded me of a Rorschach test. A black triangle framed their noses with mirrored white splotches on either side. Sharp black edged body markings and tan bodies, oryx have a regal exotic appearance. The animals stood and stared at the truck, just a few feet away.

“They love to race trucks. As soon as we start, they’ll run, then cut across us.” 

Oryx in Africa

My pup Hintza was in the back seat. I called to alert him to what was about to take place. As Ron gunned the truck, the oryx take off. Hintza had a happy moment watching them run, his head out the window. But the oryx don’t speed off into the horizon like the pronghorn I’m used to in Wyoming. They quickly get bored and resume standing and staring on the opposite side of the road.

We’re not in Africa where oryx are native to the Kalahari desert. This is the Chihuahuan Desert of New Mexico. Oryx, also known as Gemsbok, were brought here in the late 1960s. Frank Hibben, avid big game hunter, controversial archaeologist, professor at University of New Mexico, and chairman of the New Mexico Game and Fish Commission, had the bright idea of bringing oryx in for a big game hunting experience. To hunters, the barrenness of the Missile Range must have appeared as if they needed filling up. Researchers believed they’d simply stay within the Tularosa Basin, never growing beyond 500 to 600 animals. Mountain lions would control them, they said. But in Africa, prides of lions hunt them. Our solitary lions would rather take their chances on smaller, less formidable prey.

Ninety-three oryx were brought to the Missile Range between 1969 and 1973. Oryx barely need water, they eat anything with or without leaves, have no natural predators, and breed year round. Instead of self-limiting, the oryx thrived. The Land of Enchantment was now theirs for the overtaking. Six thousand today roam in southern New Mexico, and they need more and more room. Oryx inhabit not just the dry basins, but wander through mule deer and sheep habitat, stand on bajadas, invade washes, intrude on private lands, and comingle with bighorn sheep.

Looking from the Armendaris Ranch. Oryx inhabit these dry stretches of desert

Lindsay Smythe, San Andres Refuge Manager, tells me the Refuge allows depredation hunts from September through March. Hunters are escorted to the field, and told which one to shoot. Males have harems and the animals are difficult to sex.

Smythe is also concerned about disease transfer. “I will tell you on our bighorn sheep survey, I saw a lot of oryx up in sheep country. I started to count them, but finally gave up. We’re going to burn up too much fuel (in the helicopter) counting oryx instead of bighorn. They don’t get up into the highest steepest areas, but they do definitely interact.”

She wonders if the scabies outbreak that brought the sheep almost to extinction in the 1990s might not have been transferred from oryx. The timeline certainly fits, with precipitous drops in the bighorn population around ten years after the oryx introduction. Even so, the Refuge still has issues with other diseases common to bighorns which oryx definitely do transmit. Plus the science is still learning about the entire disease complex in bighorn sheep transmissible from other ungulates.

Even with over 1000 hunt tags issued every year, the NMGF can’t keep the oryx in check.

Nearby, on the Turner Armendaris Ranch, biologists are concerned about over browsing due to oryx. The Ranch holds oryx hunts every year, with reduced rates in the Fra Cristobals, bighorn country. Turner has one of the largest bighorn herds in New Mexico. The browse pressure from oryx compounds other thorny problems like drought and climate change.

Over in Nevada, a similar problem exists but with a more recognizable species. I called Mike Cox of Nevada Department of Wildlife to discuss bighorns there. Nevada once held the largest desert bighorn population in the West. The state’s classic basin-range topography was considered one huge metapopulation. When I began by asking about his biggest concern, he said “if you love wildlife in Nevada, the biggest problem that should be on the top of your to-do list is feral horses. We have more biomass of wild feral horses than the combined wild ungulate populations in the state of Nevada.”  I asked Cox where those horses were concentrated. Were they in bighorn country?

Historical range of bighorns in NV 1860, 1960, 2019

“They’re everywhere. They’re in the Mohave Desert, they’re in the Great Basin Desert, they’re in the sub-alpine, they’re in the alpine.”

“How many horses do you have?”

“About 60,000. Way too many cows, way too many horses. Our ecosystem is being destroyed as we speak. (Nevada) is going to be unable to move into the future if you overlay climate change.”

Even when I asked him about Nevada’s policies on mountain lion controls for bighorns, his response was telling.

“We shut a couple of bighorn herd hunts down, not because of disease, but because of lion predation and (Cox’s emphasis) feral horses.”

When I thought he was speaking solely of habitat destruction, he corrected me.

“They drink all the water. A bighorn will never go back to a water source that has a horse, ever. It’s their behavior. Because of that they get hugely impacted and die of thirst because the horses guard the water source for four months of the year.”

Cox segued into mountain lions and water sources. “When they have to go to a water source, mountain lions have such a great learned behavior and very efficient, so they can take their toll on the population. Mountain lions are not the reason that bighorns are in trouble, just the tip of the spear. There are a lot of things that contribute to bighorns not doing well.”

The overpopulation and mismanagement of wild horses and open range livestock is an enormously controversial topic. This essay isn’t about tackling or outlaying solutions for proper management, but to shine a light on how large, free-ranging, non-native ungulates imperil our ecosystems and our native wildlife across the West.

How to Age a Bighorn Sheep

Bighorn Sheep’s Gordian Knot Part I

When I began research for my book Ghostwalker, I learned about the messy politics surrounding reintroductions of bighorn sheep into isolated ranges of the Southwest where they once lived yet disappeared centuries ago. This noble endeavor to reintroduce a once thriving species to these sky islands and basin/range habitats had a dark underbelly. The idea was to eradicate mountain lions from the targeted range beforehand in order to enhance the sheep’s success.

Because bighorns are so fragile, because their restoration has been so fraught, I felt for the sheep. Yet the method seemed arcane at best: the lion through no fault of his own, doing only what lions do, traded for the success of a small herd on a tiny mountain range. The emotions, the circumstances, all very complicated. Therefore I left this vital piece out of my book as it begged for much further research. But the problem stayed with me. This year I decided to do a deep dive into the issue.

But to begin to wrap our heads around bighorn sheep issues, there is a lot to understand. Therefore this will be a series of posts. In my first post, I’ll begin in the area where I live with Rocky Mountain bighorns. All bighorns came to their present delicate circumstance through the same doorway, so beginning with my Rocky Mountain bighorns will lay a good foundation for understanding the more complex issues with desert bighorns.

First, my title. Truth be told I stole it. It’s been used to describe the relationship of mountain lions and desert bighorns. But having spoken with many people and done some research, I do not feel that is an adequate nor comprehensive description of what plagues bighorns. Therefore, here is a Gordian Knot as described by the dictionary:

The Gordian Knot is a legend of Phrygian Gordium associated with Alexander the Great. It is often used as a metaphor for an intractable problem (untying an impossibly tangled knot) solved easily by finding an approach to the problem that renders the perceived constraints of the problem moot.


In 2015, in the Tendoy Mountains southwest of Bozeman, Montana Department of Fish Wildlife and Parks did something unusual—they sold 311 hunt tags for any bighorn sheep in an area of only thirty sheep. Drawing a bighorn ram tag in any western state is akin to winning the lottery. Many hunters put in year after year and probably will never draw a tag in their lifetime. But this fall in Montana was different. Why? Because the Tendoy herd had been struggling for years with a respiratory disease complex with die-offs and low lamb recruitment. The heart-breaking answer the department came up with was to eliminate the entire herd and start anew. What hunters didn’t kill, the department would. Five years later, in 2020, the department announced they’d begin transplanting sheep into the Tendoys again, this time from Flathead Lake.

If you think this is a strange anomaly, it isn’t. Eliminating an entire herd that struggles with a disease complex called Mycoplasma ovipneumoniae (MOVI for short) has been done over and over in the West. But the fault lies with humans, not with the sheep.

Bighorn advocates have compared the disease to how European diseases decimated Native Americans. When European settlers brought their sheep and goats throughout the West, those animals were carriers of these bacterial diseases. Yet the domestics had built up immunity over thousands of years. But for our native bighorns, these were novel pathogens. Between disease, market hunting, habitat loss, and forage competition, native sheep populations plummeted. Original numbers throughout the Western states may have been as high as 1-2 million. By the early 20th century, they were at less than 25,000.

To restore bighorn populations where they were lost, restoration projects began in earnest in the 1960s. The most obvious idea was to move sheep. And that is what wildlife managers did, from one state to another, from one mountain to another, wherever sheep could likely thrive or had been in the past. Canada was a big exporter. So was Wyoming. It was a well-intentioned mass effort. Unfortunately, though somewhat successful, we only added to the problem. Kevin Hurley of the Wild Sheep Foundation described it to me succinctly,

“Somewhere in the future a geneticist is going to look at this and go ‘What the hell were they thinking back in the 70s, 80s, and 90s where they just blended so many sheep from so many sources’.

“The analogy I always use is a daycare. If you put a kid in a room with twenty other snotty-nosed kids, at the end of the day they’ve swapped about as much spit and goo as they can.”

In fact, it wasn’t until around 2007 or later that the lightbulb went off. Up until then, we just didn’t have the technology to understand what was really killing sheep.

When you listen to the wildlife disease experts, the terminology gets way into the weeds. When the question section comes up in zoom public meetings, the one always asked is “Can’t we just create a vaccine?” Yet that is why its called a “pneumonia complex”, because the entire issue is complex. MOVI is what HIV is to aids, it weakens the immune system, leaving it vulnerable to a host of other diseases that might not have otherwise killed a sheep. Biologists called it a “set-up artist”. The fine hairs in the respiratory tract called ciliary are damaged, the sheep are coughing, their lungs slowly destroyed. Some develop nasal tumors which make it harder to slough the disease off, becoming super spreaders (we are all familiar with that term now). Maybe they don’t even succumb to the disease, but being a life-long carrier, a typhoid Mary. The ewes that survive pass the disease along to their lambs through breast feeding. The herd then has adult death and zero recruitment. Usually the die-off of the entire herd, or a large portion, is swift.

Another major problem is that rams, looking for mates and to spread their genetics, do walk-abouts, usually in large circles encompassing 30-40 miles. Even if they begin their journey healthy, they might run into domestic lambs or goats, contract the disease, then bring it back to their herd. One ram came from Colorado into southern Wyoming, traveling over 400 miles and through three different bighorn sheep herds. Wyoming Game and Fish only knew this because the ram was collared and they were alerted by Colorado game agency. Sheep are gregarious—sheep like sheep. They don’t need to touch noses to get infected. They might even be kilometers away if the wind is right. Because Game and Fish had no idea if this ram came into contact with domestic stock, be it a large herd or a hobby rancher, they couldn’t take a chance. This one ram could cost hundreds of sheep lives and devastate entire herds. The ram was euthanized.

From Doug McWhirter 2020 presentation. Lamb Survival in three Wyoming ranges

The deeper microbiologists and veterinarians delve into the bighorn disease issue, trying to find the silver bullet cure, the messier the problem becomes. Although MOVI is a major culprit, there are a whole host of diseases. Although just in the last ten years its been accepted that domestic sheep and goats are carriers, there is now a question if cattle can add to the disease problems as well. Add to that mountain goats who are also susceptible and inhabit the same terrain, the problem thickens. Although we are clear disease is the main issue with sheep die-off, there are still major puzzles to be solved.

The Absaroka mountains have the only bighorn herd in the United States that has never been transplanted into nor out of. It is a pure, native herd with between 3500 and 4000 sheep. Although the historical evidence says that mountain goats were never native to Wyoming, a very few were transplanted in the 1960s for hunting, and have migrated into the Absarokas, sharing similar terrain with the native sheep. From a lot of blood work and studies, at last count in 2020 these native Absaroka sheep had the full compliment of pathogens. In other words, they were all carriers as far as the story told by the captured individuals. And although there have been some ups and downs in the population with disease outbreaks, their population remains stable. The mountain goats, which might present a problem in one area as they did recently in the Teton range, don’t seem to present a problem as far as researchers can tell, with the Absaroka herds. One explanation was given to me by Doug McWhirter, Wyoming Game and Fish biologist who has spent his career studying bighorns.

“Some of these pathogens could still be cycling from being introduced decades before. It tends to cycle in those animals. You could have pathogens that are residing in live animals that they pass down to offspring that don’t kill them under most circumstances, but if they are stressed by a weather event, then their immune systems can be comprised, and then at that point in time those pathogens either spread, or become more virulent and that’s when those impacts can take place.”

Raina Plowright and colleagues simple graph of MOVI crash in bighorn sheep population*

Even though there are no domestic sheep allotments on the forest today, the Beartooths were last retired as recently as 2001, and up untill the late 1980s, the headwaters of the Greybull River as well as Carter Mountain had domestic sheep on the forests. My neighbor who passed away a few years ago and grew up in this valley, born in 1926, once told me there were sheep herders all over the valley. I described a strange log structure I discovered in a nearby narrow drainage once. The drainage led to a high meadow with old campsites littered with rusty tin cans. “There were thousands of sheep up there in the summer. The log structure was probably a food cache.”

The Absarokas are littered with old Shoshone Indian sheep traps as well. Trapper Osborne Russell wrote in the 1830s how he saw thousands of sheep on the mountains surrounding the Lamar Valley of Yellowstone. Our native sheep have been exposed to domestics for a long time. Yet another pristine herd in Wyoming is crashing, probably soon to go extinct. The Whiskey Mountain herd in the Dubois area has never received sheep, but have provided many throughout the Western states. Whiskey mountain was a major supplier from the 1960s through 1990. In 1991 the die-offs began, in multiple stages, and the herd has never rebounded. Although both the Absaroka and the Whiskey Mountain herds carry the complete composite of pathogens, what makes one more resilient than the other? Biologists don’t know, but possibly environmental factors come into play—weather, food stresses, minerals like selenium, the jury is still out.

With so many unknowns, wildlife managers and conservation advocates are focusing on what they can control. Where it used to be predator controls (and still is in many respects. More on that later), the main focus has shifted to attempting to control separation between bighorns and domestic sheep and goats. That requires producers to acknowledge their sheep are the problem carriers, and then get them on board. One strategy has been offering to retire allotments, or switching allotments to non-problem areas.

Believe it or not, the expansion of grizzlies and wolves has presented real opportunities for bighorn sheep. Permittees in some circumstances are more willing to take the cash offers from private organizations to retire their grazing allotment. Yet the code of the West that enshrines livestock and private property owners has, in my opinion, strangled some of this progress. Take for instance the story of Josh Longwell. Longwell had long been in disputes with federal agencies over grazing, right-of-ways, and wildlife. As retribution, which some might call “wildlife terrorism”, Longwell abandoned grazing cattle on a high elevation grazing allotment in the Owl Creek Mountains and substituted domestic sheep, knowing they’d co-mingle with native sheep. For the Game and Fish, the risk was great, and an infected ram from the Owl Creeks that rubbed noses with Longwell’s sheep could walk-about over to the Whiskey Mountain herd and even north towards the Cody area. The Governor approved an emergency early season and licenses issued for up to 34 sheep. Longwell smugly declared this was an issue between private property and wildlife. And he may have characterized it correctly, and the government caved.

Organizations that have fought hard and long to restore bighorn sheep throughout the West have long tried to work cooperatively, versus litigating. And that is a good avenue to begin. But when it comes to the most sensitive species, an iconic species with multiple strikes against it that we are trying to restore, there are limits. Longwell represents one of those.

Kevin Hurley started our interview with a line that sums up the life of a bighorn sheep.

I go back to the early 80s, Tom Thorne, he was our wildlife vet back then. I’ll never forget the article he wrote back then in Wyoming Wildlife magazine. It was called ‘Born Looking for a Place to Die’. The whole point was they live in tough country but they’re pretty wimpy, respiratory speaking.

*Ecology Letters (Plowright, Raina K., et al. “Age‐specific infectious period shapes dynamics of pneumonia in bighorn sheep.” Ecology letters 20.10 (2017): 1325-1336.)


Stay tuned for Part II.