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As early as the late 1800s, hunting, predation and disease were decimating Sierra Nevada bighorn sheep numbers. By 1914, there were no more bighorns living in Yosemite; in 2000, when there were only about 125 Sierra Nevada bighorns left in the world, the species was listed as federally endangered.

Over the past 30 years, Conservancy donors have supported major efforts focused on bringing the endangered bighorns back from the brink. Today, the bighorn population has climbed above 600, with herds throughout the Sierra Nevada, including in Yosemite.

The bighorn survey crew hiked from Virginia Lakes to search for sheep near Yosemite's northeastern edge.

The bighorn survey crew hiked from Virginia Lakes to search for sheep near Yosemite’s northeastern edge.

Last month, Conservancy Project Coordinator Ryan got a behind-the-scenes look at the ongoing work to protect bighorns by trekking into the backcountry with biologists Sarah Stock (Yosemite) and Dr. Alexandra Few (California Department of Fish and Wildlife).

They were headed to the border of Yosemite and the Hoover Wilderness to survey the area where bighorn herds were first reintroduced to the park in 1986. This March, Sarah and Alex helped coordinate the reintroduction of a new Yosemite herd, in the Cathedral Range, adding another group of sheep to the northernmost of the four geographic units outlined in the Sierra Nevada Bighorn Sheep Recovery Plan.

Bighorn sheep rely on strong legs and padded hooves to navigate steep, rocky high-elevation environments with ease. Photo by Steve Yeager.

Bighorn sheep rely on strong legs and padded hooves to navigate steep, rocky high-elevation environments with ease. Photo by Steve Yeager.

As Sarah and Alex explained, reintroducing this majestic mammal means restoring a missing piece of the alpine ecosystem – and bringing back a long-absent symbol of wilderness. With their help, bighorns could join the tiny fraction of endangered species that have recovered and been “delisted”.

Perched on rocks near Summit Lake, at an elevation of more than 10,000 feet, the team scanned the surrounding hillsides for signs of the notoriously elusive sheep, which thrive on steep terrain, easily traversing cliff faces and narrow ledges. Impressive strength and agility, however, cannot protect bighorns from one of their biggest challenges: contact with domestic sheep, which carry diseases that can be fatal for their wild relatives.

Keeping bighorns safe requires collaboration with nearby communities, frequent monitoring and careful selection of habitat. The decision to reintroduce the newest herd to the Cathedral Range, for example, was based not only on evidence that bighorns once inhabited that area, but also on its abundant food and relative isolation from domestic grazing areas.

Yosemite wildlife biologist Sarah Stock releases a ewe into the Cathedral Range in March 2015. See the links below for video footage of that reintroduction.

Yosemite wildlife biologist Sarah Stock releases a ewe into the Cathedral Range in March 2015. See the links below for video footage of that reintroduction.

For three hours, the survey crew peered through spotting scopes and scanned for signals from the sheep’s radio collars. They saw bright wildflowers and boulders of all shapes and sizes – but no bighorns.

Later that day, they would learn that they had just missed seeing sheep during their morning hike. One of the other survey teams had used GPS signals to locate and observe a herd just across the park boundary in Inyo National Forest; another crew had spotted a few sheep grazing not far from the trail to Summit Lake. The bighorns are out there – and with collaboration, careful relocation, hours of counting sheep, and continued investment in their recovery, they are reclaiming their place as resilient mountaineers.