Some of the world’s most sacred and spectacular lands unfold across the sovereign Navajo Nation – an area nearly the size of Maine encompassing parts of Arizona, Utah, and New Mexico. 

Here, desert bighorn sheep slip silently from view in deeply tortuous canyons and among red sandstone cliffs. Carved into or painted on rock are evocative petroglyphs and pictographs of an animal hunted and revered across time.

A team comprised of Navajo tribal authorities with veterinarians and scientists from Denver Zoo, Colorado State University and the Wildlife Conservation Society recently successfully captured and released 90 bighorn sheep on Navajo Nation lands.

They aim to diagnose bighorn disease and track ecological movements by rams and ewes as the first phase of a study led by Denver Zoo. Researchers involved in the project said respiratory disease that affects these animals ultimately contributes heavily to juvenile and adult mortality. 

Today, bighorns everywhere are at a mere 5% of their historical abundance. Modern practices – roads, disease, overharvest and competition with livestock – have not played a gentle hand. 

Yet, it is here in Arizona that the Navajo Nation Department of Fish and Wildlife has been involved in reintroduction and studies to conserve and further expand this culturally important icon. By the 1990s, desert bighorn sheep on the Navajo Nation were nearly wiped out with only 34 individuals remaining, all on the San Juan River.

To prioritize the species’ recovery, Navajo Nation Fish and Wildlife, with the help of Stevens Wildlife Consulting, established the Navajo Bighorn Sheep Recovery Program in 1997. Since that time, the teams successfully established two additional populations of bighorn sheep on Navajo lands.

Populations steadily increased and peaked at 600 animals in 2016, but a pneumonia epidemic now threatens that recovery, sending two of three populations into precipitous decline.

Jessica Fort, wildlife biologist for the Navajo Nation and the architect of a recent ongoing conservation effort, said she is enthused about the project’s potential.  “We hope that the bighorn sheep can continue to play an important role, ecologically, economically, and culturally in The Nation’s future,” she said.  

The project also aims to assess disease prevalence in the Navajo Nation’s wild bighorn populations. Supported by $260,000 in grants from the Bureau of Indian Affairs and U.S. Fish and Wildlife Service, the project covers the remote northern lands of the reservation, with boundaries that expand southward from the San Juan River and from Glen Canyon units managed by the U.S. National Park Service.

Jeff Cole, wildlife manager of the Navajo Fish and Wildlife Department said there is real value added to the project, thanks to cooperation among tribal authorities with state and federal agencies, coupled with university and non-government organizations.

“If we really want our bighorn sheep populations to thrive, we need a broader knowledge base and a way to ensure that people are involved in building solutions while also incorporating the latest science,” he said.

The year 2020 has proved to be a very tough year on Navajo Nation, the USA, and the world.

Joel Berger, the Barbara Cox-Anthony Chair of Wildlife Conservation at Colorado State University and senior scientist at Wildlife Conservation Society, said the successful collaboration should be applauded.  

“When the centrifuge we used to process the bighorn samples in the field failed, we had offers from Navajo communities some 150 miles away to help, as well as from the Bureau of Land Management, from private veterinary clinics and from local hospitals,” he said. “People are cooperating for a common good and for a species of great local relevance to the Navajo people, and that is something to be celebrated.”  

The second phase of this research project will include a collaboration with local domestic sheep herders to identify possible disease reservoirs, and ultimately suggest solutions to prevent the spread of disease. 


Navajo Nation Department of Fish and Wildlife–Navajo Nation is a federally-recognized Indian tribe with 18 million acres of land in Arizona, New Mexico and Utah.  The mission of Navajo’s Department of Fish and Wildlife is to “conserve, protect, enhance, and restore the Navajo Nation’s fish, wildlife, and plants through aggressive management programs for the spiritual, cultural, and material benefit of present and future generations of the Navajo Nation.”


Denver Zoo – Home to almost 3,000 animals representing more than 450 species, Denver Zoo is a non-profit 501(c)(3) organization, and the city’s oldest and most passionate advocate for the natural world. The Zoo is among the most visited cultural destination in Colorado, serving almost 2 million people per year, and accredited by the Association of Zoos and Aquariums (AZA), which assures the highest standards of animal care. With the mission inspiring communities to save wildlife for future generations, Denver Zoo dedicates almost $2 million annually to Zoo-led programs aimed at protecting animals within their natural habitats around the world. For more information, visit