{"id":24013,"date":"2025-01-14T19:43:37","date_gmt":"2025-01-15T02:43:37","guid":{"rendered":"https:\/\/dh.durangoherald.com\/tj\/disease-die-offs-continue-to-ravage-bighorn-sheep\/"},"modified":"2025-01-15T02:43:37","modified_gmt":"2025-01-15T02:43:37","slug":"disease-die-offs-continue-to-ravage-bighorn-sheep","status":"publish","type":"post","link":"https:\/\/dh.durangoherald.com\/tj\/disease-die-offs-continue-to-ravage-bighorn-sheep\/","title":{"rendered":"Disease die-offs continue to ravage bighorn sheep"},"content":{"rendered":"\n

\"Scientists
Scientists estimate that at the start of the 19th century, up to 2 million bighorn sheep may have roamed the mountains of North America. (Andrea Kramar\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

COLORADO SPRINGS \u2013 The Pikeview Quarry, barely outside of the cul-de-sacs and two-car garages of the Mountain Shadows subdivision, seemed like an odd place to find one of Colorado\u2019s most intrepid species. Bulldozers, excavators and dump trucks crawled the quarry\u2019s terraced slopes, putting the final touches on a mine reclamation effort that began in 2022.<\/p>\n

Despite the human-made noise, Colorado Parks and Wildlife biologist Ty Woodward spotted a band of eight bighorn sheep grazing the rusty slopes of the quarry.<\/p>\n

\u201cEven though you have the machines running around here, there\u2019s not a ton of people,\u201d Woodward said.<\/p>\n

The quarry \u2013 which once provided Colorado Springs with the limestone aggregates needed to make concrete \u2013 has become a surprise haven for bighorn sheep, providing the steep slopes, visibility and food they need to survive.<\/p>\n

Not all of Colorado\u2019s rocky mountain bighorn sheep have fared this well. Experts estimate that at the start of the 19th century, between 1.5 million and 2 million bighorn sheep roamed the mountains of North America. Today, roughly 80,000 remain in the region, with just 7,000 left in Colorado.<\/p>\n

Hunting, competition for habitat and diseases carried by domestic sheep and goats decimated the species.<\/p>\n

Although Colorado\u2019s bighorn sheep population has stabilized on paper, wildlife officials have failed to \u201cfully restore the species,\u201d said Terry Meyers, executive director of the Rocky Mountain Bighorn Society.<\/p>\n

One of the top threats to the species is a string of respiratory diseases that infect and kill bighorn sheep. Domestic sheep and goats transmit pathogenic bacteria \u2013 most notably mycoplasma ovipneumoniae \u2013 to bighorns through nose-to-nose contact. While these bacteria are usually innocuous to livestock, they can rapidly develop into deadly cases of pneumonia in wild sheep.<\/p>\n

Contact between the two species happens more often than biologists would like. Bighorn sheep are often curious about their domestic cousins and frequently encounter domestic sheep on public grazing allotments that overlap with their habitat.<\/p>\n

At least seven bighorn herds suffered from respiratory illnesses in 2023, leading some biologists to declare it the \u201cworst year in over a decade for bighorns in Colorado.\u201d In the past, disease events have wiped out entire herds, and when one band of sheep gets sick, it can be hard to prevent bighorns from infecting other herds.<\/p>\n

Although scientists have long dreamed of a vaccine, no such antidote exists.<\/p>\n

\u201cThe only management strategy to really protect bighorn sheep is separation between bighorn sheep and domestic sheep,\u201d Meyers said. Such separation is easier said than done considering bighorn rams can travel up to 60 miles in search for mates.<\/p>\n

Powerless to enact change<\/div>\n

State wildlife biologists and researchers who are most familiar with the threat of disease are largely powerless to enact change. Colorado Parks and Wildlife can manipulate hunting licenses, improve habitat or move bighorn sheep, but when it comes to conflicts with domestic sheep on federal grazing lands, it is up to federal agencies to make changes.<\/p>\n

According to Meyers, the U.S. Forest Service and Bureau of Land Management, which control grazing permits, have taken a laissez-faire approach to conflicts between bighorn sheep and domestic sheep, rarely completing environmental analyses on grazing allotments.<\/p>\n

In many cases, conservation hinges upon individuals and advocacy groups who have pieced together arrangements with ranchers to give up grazing rights in problematic areas and provide more space for bighorns.<\/p>\n

\"Ty
Ty Woodward ascends the terraced slopes of Pikeview Quarry. For a good shot he must get within 25 yards of the bighorn sheep. (Cormac McCrimmon\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n
\"Ty
Ty Woodward, a wildlife biologist with Colorado Parks and Wildlife prepares a tranquilizer dart to immobilize a bighorn sheep ewe in order to collar the animal. (Cormac McCrimmon\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

Despite the intractability of the problem, wildlife biologists manage and track bighorns as best they can. During a recent field operation at the end of December, Woodward planned to dart and collar a bighorn ewe so that his team can better understand the herd\u2019s movements and behavior.<\/p>\n

At the base of the Pikeview Quarry, Woodward and his colleague Corey Adler prepared a carbon-dioxide tranquilizer gun they use to dart the sheep. They must get within 25 to 30 yards for a good shot.<\/p>\n

Once the sheep is tranquilized, they secure a GPS tracking collar. Location data from collars help CPW understand bighorn sheep movement and population health. When a collared sheep dies, biologists are more likely to find its body in time to collect tissue samples that scientists can study.<\/p>\n

Although the Rampart herd is currently disease-free, CPW regularly monitors the population to ensure it remains healthy. They use this herd to create new herds and bolster ailing herds around the state.<\/p>\n

The herd at Pikeview Quarry descended from 14 bighorn sheep that were originally destined for Pikes Peak. In 1946, a truck carrying the sheep broke down. The drivers released the sheep near Green Mountain Falls thinking they would make their way toward Pikes Peak. Instead, the herd colonized a series of canyons and rocky slopes above the Garden of the Gods.<\/p>\n

It didn\u2019t take long for bighorn sheep to become a fixture in the area.<\/p>\n

Jerry Schnabel, president of Castle Aggregates, which operated Pikeview Quarry, said that even rough and tough miners soon developed a soft spot for sheep. Miners with names like \u201cDozer Dave\u201d would haul water to the top of the quarry to help the sheep survive dry spells, he said.<\/p>\n

Schnabel even found invoices for hay the miners had ordered from a local rancher to feed the bighorns.<\/p>\n

To this day, the peri-urban herd provides easy access for citizens and scientists to observe the species.<\/p>\n

More accepting toward humans, but still wild animals<\/div>\n

Adler and Woodward piled into an off-road vehicle to make the initial ascent up the quarry on a recent research trip. Although the bighorn sheep here have grown accustomed to heavy machinery, they remain highly attuned to predators.<\/p>\n

Near the top of the quarry, they parked and continued on foot. The wind carried their scent toward the sheep, but Woodward and Adler thought that if they stayed hidden behind an outcrop, then army-crawled into position, they would be close enough to take a shot.<\/p>\n

At the base of the quarry, Brandon Bagon, a terrestrial wildlife technician, tracked the sheep through a spotting scope.<\/p>\n

Woodward grew up in Lamar. He remembers fishing trips with his grandmother and summers spent catching lizards and snakes. It wasn\u2019t until college, when he worked as a technician for Colorado Parks and Wildlife, that he fell in love with ecology.<\/p>\n

\u201cI was a history major until I learned this was a job,\u201d Woodward said.<\/p>\n

He and Adler tiptoed through a patch of old snow.<\/p>\n

The gun was loaded. The sheep were fewer than a hundred yards away.<\/p>\n

Suddenly, a ewe lifted her head. She sniffed the air then paused. The men hunkered at the back of the terrace until the sheep returned to their food.<\/p>\n

Woodward and Adler crept along the edge toward a boulder right above the sheep.<\/p>\n

But the radio crackled.<\/p>\n

\u201cThey bolted,\u201d Bagon said.<\/p>\n

The sheep bounded up a shelf at the south end of the quarry. They raced into a grove of standing dead trees. They were gone.<\/p>\n

\u201cEven though they act a little more accepting toward humans, they\u2019re still wild animals, and they\u2019re going to do wild things,\u201d Woodward said.<\/p>\n

Across the state, winter offers the best window for bighorn sheep research when herds descend to more accessible terrain and cooler weather makes it safer for biologists to handle the animals without harming them.<\/p>\n

In addition to ground missions, like the one at Pikeview Quarry, CPW uses small planes and helicopters to conduct annual surveys of bighorn sheep populations. These data help biologists adjust the number of hunting licenses and understand where disease conflicts may exist.<\/p>\n

One of the problems researchers face in addressing respiratory diseases is that by the time a disease outbreak becomes apparent, it can be too late to take action. Because bighorn sheep are often visible throughout the Front Range, it\u2019s easy for people to assume that the species is thriving, Meyers said.<\/p>\n

\u201cThe animals are really good at hiding what\u2019s going on so that they don\u2019t show signs of weakness to predators,\u201d said Karen Fox, \u200b\u200ba veterinary pathologist and research scientist at Colorado State University.<\/p>\n

\u201cBut when I get them on the necropsy floor and I open them up, I find the lesions. Some of these animals are so badly affected that they are coughing. They have mucus pouring out of their noses.\u201d<\/p>\n

At times, disease outbreaks have dramatic outcomes, like the Trickle Mountain die-off. Between 1992 and 1993, pneumonia reduced the Saguache County population from 400 bighorn sheep to 200. By 2010, the Trickle Mountain herd had just 35 sheep left.<\/p>\n

More recently, disease die-offs have taken a more imperceptible form, striking lambs and leading to a slow decline in a herd\u2019s numbers.<\/p>\n

\u201cIt\u2019s kind of an evil irony. Each year the lambs will be born and the lambs look perfectly healthy. They\u2019re sprite. There\u2019s a good number of lambs per ewe. As the summer progresses, though, and we get closer and closer to fall, you\u2019ll start noticing fewer and fewer lambs with the ewe, and then eventually, we start observing sick lambs on the landscape. It\u2019s heartbreaking,\u201d Woodward said.<\/p>\n

Biologists have traced the current die-off among the Pikes Peak bighorn herd to an incident in 2021 when domestic sheep escaped from a small-scale \u201chobby\u201d farm. Hunters alerted CPW. When they found the domestic sheep, they were corralled in a canyon that happens to be a primary migration corridor for the area\u2019s bighorns.<\/p>\n

\u201cIt couldn\u2019t have been at a worse time of year. It was right at the beginning of the lambing period, in which those sheep were moving down from Pikes Peak into their lambing area, at the end of this canyon,\u201d Woodward said.<\/p>\n

CPW tracked the bighorn lambs born that year. By November, they had observed 16 ewes without lambs.<\/p>\n

\u201cWe knew at that point that we were seeing a pneumonia related die-off,\u201d Woodward said.<\/p>\n

Since then, he and fellow researchers have observed other sick lambs on the peak.<\/p>\n

\u201cIt\u2019s not easy to watch,\u201d he said, describing the cough as \u201cguttural.\u201d<\/p>\n

\u201cYou could see it in their stomach. You could see all their muscles contracting. It has a very distinct sound, almost like a metal can being rattled with rocks inside.\u201d<\/p>\n

\"Bighorn
Bighorn sheep at Rocky Mountain National Park. (Courtesy of National Park Service)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

Another problem researchers face is that respiratory diseases stem from many different types of viruses \u2013 which makes the possibility of developing a vaccine more difficult.<\/p>\n

Karen Fox began studying respiratory disease in bighorn sheep during her doctorate in 2009. Today, her research seeks to understand the genetics of disease-causing bacteria to see if she can identify patterns that correlate to better or worse outcomes in infected animals.<\/p>\n

Researching the diseases<\/div>\n

At the Veterinary Diagnostic Laboratory at Colorado State University, Fox pulls from a freezer with over 800 tissue samples collected from dead bighorn sheep\u2019s lungs, respiratory tract or tonsils.<\/p>\n

So far, Fox has analyzed just 200 of the 800 samples, but she hopes this research will offer more accurate predictions of how sick herds will fare.<\/p>\n

\u201cIf we find that there\u2019s certain strains of bacteria that are causing certain diseases in the bighorn sheep populations, then maybe we can use that information to develop tools for management, things like vaccination,\u201d Fox said.<\/p>\n

\u201cThat hasn\u2019t been a super successful approach in bighorn sheep so far, but maybe we just haven\u2019t found the right strain to make a vaccine against.\u201d<\/p>\n

\"Karen
Karen Fox analyzes DNA synthesized from a bighorn sheep tissue sample. Her work seeks to better understand the genetic patterns of disease-causing bacteria. (Cormac McCrimmon\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n
\"Karen
Karen Fox has collected over 800 tissue samples from dead bighorn sheep. The picture shows a sample through Fox\u2019s microscope. (Cormac McCrimmon\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

Despite an abundance of research showing viruses from domestic sheep and goats can infect and harm bighorn sheep, \u201cthere is a lot of denial of the science,\u201d said Meyers, referring to both ranching groups and federal land managers that have minimized the risks of the disease.<\/p>\n

According to Meyers, ranchers insist that other animals are to blame or that bighorn sheep have already been exposed, so the risk of disease is nonexistent.<\/p>\n

For now, separation between bighorn sheep and domestic sheep and goats is the only surefire way to prevent the spread of disease. But according to Meyers, more than 100 of the state\u2019s roughly 480 domestic sheep grazing allotments that are on forest service or BLM land directly overlap with bighorn sheep herds. Roughly 180 more are within 9 miles of a herd.<\/p>\n

\u201cWe don\u2019t have control over what people do on their private lands, but on public lands, we should be able to protect bighorn sheep from the potential for exposure to viruses,\u201d Meyers said.<\/p>\n

In the San Juan Mountains<\/div>\n

In Colorado\u2019s San Juan Mountains, glaciers from the last ice age gnawed away at the volcanic debris making way for an ocean of grass. Today, a chorus of \u201cbaaas\u201d and bells provide the soundtrack of grazing season.<\/p>\n

Ernie Etchart grew up raising sheep in these mountains. His father, originally from the Basque Country of Spain, came to the U.S. as a shepherd in 1947. When a neighboring rancher offered Etchart\u2019s father the opportunity to buy his operation, he leaped at the chance to own his own sheep. In 1986, he turned the business over to his sons. Today Ernie Etchart and his brother George Etchart run roughly 3,200 ewe-lamb pairs.<\/p>\n

In 2023, Etchart made headlines when he agreed to relinquish five grazing allotments, totaling over 100,000 acres above Silverton in order to protect bighorn sheep in the area.<\/p>\n

According to Etchart, before the deal he faced increasing pressure from bighorn sheep advocates. Other challenges, like difficult access and increasing recreation in the area added to the strain.<\/p>\n

\u201cWe\u2019d been getting pressure from the Bighorn Sheep Society for a number of years. They of course put pressure on the Forest Service and BLM, which in turn would put pressure on us,\u201d Etchart said. \u201cThey wanted us to be perfect out there, and sometimes that\u2019s pretty tough to be perfect when you\u2019re dealing with animals.\u201d<\/p>\n

After thorough consideration, Etchart accepted a deal to waive his grazing rights in exchange for an undisclosed sum of money from the National Wildlife Federation. In response, federal agencies agreed not to restock the grazing allotments. Since accepting the deal, Etchart has begun grazing on private land near Norwood and Ridgway.<\/p>\n

\u201cIt was a hard decision, but there were a lot of issues for us with those permits. We had to make a business decision,\u201d he said.<\/p>\n

\"Ernie
Ernie Etchart is a second-generation sheep rancher based in Montrose. In 2023, he made national headlines for a deal with the National Wildlife Federation to waive grazing allotments in an area with bighorn sheep conflicts. (Andrea Kramar\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n
\"ATVs
ATVs ascend a dirt road in the San Juan Mountains. Ernie Etchart said that increased recreation in the area was a major factor in his decision to waive his grazing rights. (Ziyi Xu\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

In spite of the agreement, Etchart remains skeptical about the risk domestic sheep pose to bighorns.<\/p>\n

\u201cThere\u2019s a lot to be known about the risk of disease transmission between domestic sheep and bighorn sheep,\u201d he said.<\/p>\n

He points to the success of the San Juan west herd \u2013 one of the state\u2019s healthiest \u2013 in spite of long-term grazing in the area, along with the availability of bighorn sheep tags in Colorado as evidence that the species is thriving (in 2024 CPW issued 336 bighorn tags to hunters).<\/p>\n

\u201cJust because we haven\u2019t had a die-off in 20 or 30 years in a particular herd, doesn\u2019t mean it\u2019s not going to happen,\u201d Meyers said. \u201cWhen we look around the state and we look around the West, these die-offs are happening every single year. It\u2019s just a matter of time before the next exposure happens that causes a die-off in the herd.\u201d<\/p>\n

Despite the success of voluntary permit waivers like Etchart\u2019s, Meyers, who has helped to facilitate four other such deals with Colorado ranchers, sees the tool as a temporary solution.<\/p>\n

\u201cThere is not enough money with NGOs to fix all of these problems. And while compensated permit waivers are very appealing to the federal agencies because it gets them off the hook without making a decision, we can\u2019t do it all. There\u2019s only enough money available for us to undertake one of these agreements every year or year and a half,\u201d he said.<\/p>\n

Feds manage lands to \u2018detriment of bighorn sheep\u2019<\/div>\n

Meyers attributes the lack of change at a government level to several factors.<\/p>\n

First, wildlife biologists who monitor bighorn sheep have few management tools to resolve disease conflicts. CPW can repopulate herds with healthy sheep, change the number of hunting licenses or work on habitat restoration, but when it comes to conflict with ranchers, it is ultimately up to federal agencies who oversee grazing permits to make changes.<\/p>\n

In 2009, Colorado Parks and Wildlife, the Colorado Wool Growers Association, the BLM and U.S. Forest Service signed an agreement \u201cthat the wildlife agency would not advocate for closure of domestic sheep allotments based solely on the risk to bighorn sheep,\u201d Meyers said.<\/p>\n

Although the agreement was not re-signed in 2019, it remains up to federal agencies to respond to management suggestions made by CPW.<\/p>\n

\u201cFederal agencies are responsible for managing the land, and they\u2019re in large part not responding to all of those comments in a way that\u2019s favorable to bighorn sheep. They continue to manage the lands to the detriment of bighorn sheep in many areas,\u201d Meyers said.<\/p>\n

In theory, federal agencies are supposed to reevaluate grazing permits every 10 years when the permits expire.<\/p>\n

Lacking resources to analyze every permit, federal agencies turned to Congress to ask for additional time to complete the requisite environmental assessments of grazing allotments.<\/p>\n

In 2015, Congress passed a rider provision alongside the National Defense Authorization Act. The measure required federal agencies to renew permits under the existing terms and conditions.<\/p>\n

\u201cIt essentially took the agencies off the hook of ever doing National Environmental Policy Act analysis on grazing allotments,\u201d Meyers said. \u201cThey still do what they can, but they don\u2019t undertake the difficult ones with challenging resource conflicts like bighorn sheep, because those are very time consuming and costly.\u201d<\/p>\n

\u201cFederal agencies are leaving us high and dry. They\u2019ve abandoned us on this issue. They and Congress really need to step up and help us all solve this problem,\u201d Meyers said.<\/p>\n

\"Terry
Terry Meyers is the executive director of the Rocky Mountain Bighorn Society. Meyer is frustrated by the U.S. Forest Service and Bureau of Land Management\u2019s apathy toward protecting bighorn sheep. (Ziyi Xu\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n
\"Terry
Terry Meyers searches for bighorn sheep outside of Silverton. The area has become ground zero for conflict between domestic and bighorn sheep. (Ziyi Xu\/Rocky Mountain PBS)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

Despite a lack of promising solutions, bighorn sheep advocates see glimmers of hope. Meyers points to decisions like Vail\u2019s recent settlement that will protect winter range for bighorn sheep as evidence that people do care about the species, especially when they understand the problem bighorns are facing.<\/p>\n

Later this year, Woodward and his team plan to relocate a portion of the Rampart Herd to a wildfire burn zone west of Pueblo \u2013 the fire-thinned vegetation, creating new habitat for the species.<\/p>\n

Meyers sees education as a key steppingstone toward future conservation. He pointed to the success of other wildlife campaigns like \u201cBe Bear Aware.\u201d Moving forward he hopes to collaborate with CPW and the Department of Agriculture to develop a similar education program focused on bighorn sheep.<\/p>\n

\u201cThen, maybe when people are out mountain biking on national forest lands and they encounter a big herd of domestic sheep, it will make them stop and wonder about why those sheep are there and what potential impacts they might be having on bighorn sheep,\u201d Meyers said.<\/p>\n

It\u2019s unlikely that bighorn sheep will ever recover to the pre-colonization numbers \u2013 in fact, populations that are too dense could make disease transmission more likely. But for bighorn sheep advocates, the fight to protect the species is driven by a desire not just to protect nature, but to save a symbol that has come to embody wildness itself.<\/p>\n

\u201cWe\u2019re stewards of the ecosystem. We\u2019re stewards of the country and where we live. And it\u2019s our obligation to protect wild species,\u201d Meyers said.<\/p>\n

To read more stories from Rocky Mountain PBS, visit www.rmpbs.org<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Advocates say feds left them \u2018high and dry.\u2019 What is Colorado doing to protect iconic species?<\/p>\n","protected":false},"author":1,"featured_media":24014,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[],"tags":[1031,289,28,603],"naviga_topic":[],"class_list":["post-24013","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-colorado-parks-and-wildlife","tag-disease","tag-headlines","tag-wildlife"],"acf":[],"author_name":"dh_admin","_links":{"self":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/24013","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/comments?post=24013"}],"version-history":[{"count":0,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/24013\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media\/24014"}],"wp:attachment":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media?parent=24013"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/categories?post=24013"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/tags?post=24013"},{"taxonomy":"naviga_topic","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/naviga_topic?post=24013"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}