Summit County Citizens Voice

Colorado biologists to study bighorn sheep herds in the San Juans. PHOTO COURTESY CDOW.

Biologists learning more about big game movement in the San Juans

By Summit Voice

SUMMIT COUNTY —Colorado Parks and Wildlife Biologists are studying how elk and bighorn sheep in southern Colorado move in an effort to better manage some of the state’s charismatic wildlife.

“These studies will help us to learn important information about the elk and bighorn populations in this area of Colorado,” said Stephanie Steinhoff, terrestrial biologist for Colorado Parks and Wildlife in the San Luis Valley.

The studies are being conducted in the south San Juan Mountains on the west side of the San Luis Valley and east of Pagosa Springs.

In the elk study, 25 animals — eight bulls and 17 cows — were captured and fitted with VHF radio collars which allow biologists to track the animals’ movements from the air. The animals were captured in mid-February. At least part of the elk herd migrates into New Mexico, but wildlife biologists are not sure how far they go.

To estimate elk populations, Parks and Wildlife staffers conduct what are called “classification flights.” Biologists fly over areas where elk herds gather during winter and conduct population surveys. Then, using specialized survey techniques, harvest results, historical information, survival rates and computer analysis, biologists estimate herd composition and size.

For the study, biologists will fly over the area to locate elk via the signal from the collars. They’ll then provide the location to another crew that will fly over the area in a helicopter in a specific pattern and try to spot and count elk. That crew’s count will then be compared with the counts that are made during the regular classification flights.

“We know that on our survey flights we see only a fraction of the elk that are on the ground,” Steinhoff explained. “This study will help us learn more about what factors prevent us from seeing animals or help us to spot animals in certain types of terrain. That will help us improve our classification flights and modeling techniques,” Steinhoff said.

Battery life on the radio collars is from three to five years; research will continue as long as the batteries last.

In the bighorn sheep study, biologists will try to learn why one of the three herds in the southern San Juans is declining.

In mid-February biologists captured seven bighorns — five ewes and two rams. Each was fitted with a GPS transmitter collar enabling biologists to track their movements continuously. Nasal and oral swabs and blood samples were also taken for disease testing.

Researchers want to learn how far these bighorn sheep move from year to year, if they interact with the other bighorn herds and if they venture into areas grazed by domestic sheep. Bighorns are susceptible to diseases carried by domestic sheep.

The collars will last about three years. Steinhoff hopes that more collars will be put out in the future.

“We don’t have much information about these bighorn herds, so the data we gather will be very valuable,” Steinhoff said.

Filed under: biodiversity, Colorado Division of Wildlife, Colorado State Parks, Environment Tagged: | bighorn sheep, Colorado, elk, wildlife