Utah’s Zion National Park is experiencing a sheep boom, and experts say some of the animals may have to be transported outside the park to keep the herd healthy. According to park officials, a recent survey counted more than 500 desert bighorn sheep living within and outside the boundaries of the park. Since such a dense gathering of sheep can promote disease in both the bighorn and nearby domestic goats and sheep, the Utah Division of Wildlife Resources (UDWR) is working with the park to determine management actions.
How much is too much of a good thing? Biologist Cassie Waters told The Salt Lake Tribune the park can hold about 800 bighorn sheep, but such a high density of animals could lead to fatal diseases such as pneumonia. Respiratory diseases are especially dangerous to bighorn sheep and are commonly contracted from domestic sheep since they are behaviorally attracted to each other. Outbreaks of pneumonia can devastate entire herds, and according to the UDWR, 88 percent of pneumonia die-offs occur within three years of peak population estimates.
However, Zion’s bighorn population is still healthy. Although cases of sore mouth disease were reported last year, park officials agreed they see no signs of die-offs. Biologists are hoping to keep it this way by trapping and transferring a number of sheep to boost restoration efforts in other areas.
“Since this has been determined to be a healthy population, we want to keep it that way,” Zion National Park’s Division Chief of Natural Resources Fred Armstrong told the Deseret News. “By keeping densities lower, there won’t be significant stress on the herd from competing for resources.”
Between 20 to 100 of the animals may be transplanted elsewhere, either supporting an existing population or starting a new one. Zion National Park’s own bighorn population has not always been the largest in Utah. In fact, there were no bighorn sheep in the park before 1973, when the species was reintroduced. After decades of restoration efforts, it seems the sheep have finally gained a foothold in their native habitat.
“Zion is really good habitat,” said UDWR Bighorn Program Manager Dustin Schaible. “When you have good habitat, populations just grow.”
The transplant proposal will be open to public comment until March 19.
Image courtesy Zion National Park