Desert Bighorn Sheep Populations Being Studied to Determine Disease Impacts

by Jennifer Shea
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Desert bighorn sheep have been dying off for years due to diseases like pneumonia and the disappearance of their habitat. Now a team of Navajo Nation tribal members, veterinarians and biologists are studying the sheep in an area of desert land that stretches across Arizona, New Mexico and Utah.

Desert Bighorn Sheep Population Dropping

The area is part of the sovereign Navajo Nation. And in December of last year, Navajo tribal authorities joined with scientists from Colorado State University and the Wildlife Conservation Society and veterinarians from the Denver Zoo to capture and release 90 bighorn sheep, per Phys.org.

It was the first stage of a study led by the Denver Zoo. The study’s goals are to diagnose respiratory diseases in the bighorn sheep and to track their movements across the territory.

Moreover, Navajo Fish and Wildlife Department wildlife manager Jeff Cole said the study is helping to build toward a future in which stakeholders have the knowledge and cooperative relationships to protect the bighorn sheep population.

“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.

In recent years, the bighorn sheep population had dwindled from its historical peak. By the 1990s, there were just 34 desert bighorn sheep left on the Navajo Nation’s land.

So Navajo Nation Fish and Wildlife launched the Navajo Bighorn Sheep Recovery Program in 1997. Since then, the program has created two additional populations of bighorn sheep in the area. 

By 2016, there were 600 desert bighorn sheep on Navajo lands. But now a pneumonia epidemic has spread through two of those three populations.

A Cooperative Conservation Effort

Bighorn sheep are important to the Navajo. The animal also features prominently in petroglyphs and pictographs that decorate the rocks on their land.

The Navajo Nation is an Indian tribe with federal government recognition. It owns 18 million acres of land across Arizona, New Mexico and Utah.

Jessica Fort is a wildlife biologist for the Navajo Nation and the force behind a recent long-term conservation effort. She said the study has to succeed.

Furthermore, “we hope that the bighorn sheep can continue to play an important role, ecologically, economically and culturally, in the Nation’s future,” she said.

Right now, scientists are analyzing tissue samples from the bighorn sheep. They’re screening for Mycoplasma ovipneumoniae, a respiratory pathogen that has caused deadly pneumonia in wild sheep and goats. They are also monitoring the rams to find out if they’re visiting domestic herds of sheep, which can spread the pathogen.

The next step in the project is to work with local domestic sheepherders to track down potential respiratory disease reservoirs. And the ultimate goal is to find solutions to stop the spread of respiratory disease.

The study draws its funding from federal grants. They got $260,000 from the Bureau of Indian Affairs and the U.S. Fish and Wildlife Service.         

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