Due to the rugged landscape and remote location of the sheep, the animals were captured by a wildlife helicopter capture company using a net gun. The sheep were then secured and carried under the helicopter to a working site where they were tested for disease and outfitted with radio collars.
Griffin said there is archaeological evidence of bighorn sheep in the release area in the form of tools made out of bighorn bones and petroglyphs. The transplant was funded by the Foundation for North American Wild Sheep.
The bighorns moved this week were most likely part of a transplant that took place in 1973 when a dozen desert bighorn sheep were moved from the Lake Mead area in Nevada to Zion National Park. Bighorn sheep were native to the area but had disappeared in the 1950s due to a combination of factors, most of them human-caused.
The sheep from Nevada were kept in pens until their numbers reached 20 animals and they were released. The transplanted animals were not seen again, and it wasn't until the 1990s that visitors to Zion National Park started to report bighorn sightings.
By 2009, a survey conducted by Utah wildlife biologists turned up 115 bighorn in Zion National Park and 114 on lands south of the park.
The Utah Wildlife Board created a desert bighorn hunt for fall 2010 on the Zion unit south of the national park. Hunting is not allowed in Zion National Park, and no animals captured this week for the transplant came from inside the park.