Last month, veterinarians and scientists from the Denver Zoo and Colorado State University were among those working with the Navajo Nation to capture, tag and release 90 desert bighorn sheep.

Desert bighorns, reports CSU’s campus news service, now constitute 5% of their historical numbers, with diminution of the species caused by disease, overharvest and human intrusion. Only 34 desert bighorns existed on the Navajo Nation in the 1990s. The reservation borders Colorado on its southwest corner, spanning Arizona, New Mexico and Utah.

The project received $260,000 from the Bureau of Indian Affairs and the U.S. Fish and Wildlife Service. The team of tribal authorities and wildlife professionals seeks to diagnose respiratory disease in the young animals, which leads to high mortality, and also to track their movements.

Pneumonia is a current danger to the population’s recovery, and the second phase of the research project will attempt to find solutions to prevent disease spread.

“We hope that the bighorn sheep can continue to play an important role, ecologically, economically and culturally, in the Nation’s future,” Jessica Fort, wildlife biologist for the Navajo Nation, told CSU.

Desert bighorns are related to the Rocky Mountain bighorn sheep, which is Colorado’s state animal and the symbol of Colorado Parks and Wildlife. Rocky Mountain bighorn are not endangered, but threats to their numbers include loss of habitat and disease.