Black Ridge desert bighorn sheep herd back on healthy course

Desert bighorn ewe wearing an eartag and radio collar stops grazing long enough to eye a photographer. Biologists use the tags and radocollars to monitor the Black Ridge herd, tracking track sheep movement and estimating herd populations.

A female desert bighorn sheep stands guard over her lamb. A recent study of the sheep in the Black Ridge herd indicates the sheep are lambing earlier, in January and February, than desert bighorn sheep in other herds around the state.

A desert bighorn ram peers around a boulder in Colorado National Monument. Bighorn sheep are popular among visitors to the monument and often are seen in Monument Canyon and along Rim Rock Drive near Balanced Rock.

When Montana hunter Dick Sapa recently became the first nonresident hunter to harvest a desert bighorn ram from the Black Ridge herd, his trophy was notable for more than simply being the first of its kind.

Sapa’s ram, estimated at 9.5 years old and sporting magnificent 5/8th curl horns, also marked the continuing health of a sometimes troubled herd of bighorn sheep haunting the steep canyon country west of Grand Junction.

The fact a nonresident license was available, plus four resident ram licenses, for a sheep herd where hunting was discontinued for a decade, show the advances made in sheep management by the Colorado Division of Wildlife.

Although bighorn sheep sightings now are common along several trails within Colorado National Monument, that’s a fairly recent development.

Scientists are hard-pressed for definitive proof that bighorn sheep lived in the rugged slickrock canyons of western Colorado prior to the coming of Europeans.

However, a scattering of rock art panels in Colorado National Monument indicate the unknown artist(s) had some contact with bighorn sheep, either here or elsewhere.

Early explorers make no mention of seeing bighorn sheep around the Grand Valley but it’s known bighorn sheep did exist down river, west of the present state line.

Biologists say it’s possible bighorn sheep may have utilized the river corridor from near Colorado National Monument to down river of Westwater, Utah, where sheep are found today.

What might have extirpated the sheep is anyone’s guess.

Predation, particularly from mountain lions, today is the leading cause of sheep mortality, but 100 years ago the sheep, if they had survived so long, also had to deal with overharvesting, habitat loss, competition from domestic livestock and other tentacles of development accompanying the westward expansion of a booming human population.

“If there were sheep around the area, they were gone by the 1800s because we haven’t any records of them,” said Stephanie Duckett, terrestrial biologist for the Colorado Division of Wildlife in Grand Junction.

Duckett is in the midst of a multi-year project monitoring the bighorn sheep in the Black Ridge herd, and even though it’s early in the study, at least two significant factors have been revealed.

One, that the sheep breed and have their lambs several months earlier than other sheep herds, and that the Black Ridge herd is doing much better than expected.

“We didn’t have a real good handle on the sheep population until we began our marked resighting study” in 2007, Duckett said recently. “We started the project to get more information on the herd, and that’s really paid off.”

Marked resighting entails capturing an animal, putting an identifying ear tag or radio collar on it and then going out later and trying to find the animal.

What the DOW discovered, and what led to Sapa’s recent successful hunt, is that the Black Ridge herd numbers around 200 animals, nearly three times recent estimates.

“We now have a really good snapshot of the sheep populations and we feel the number of sheep can sustain the number of licenses we issued,” Duckett said.

The present herd initially was established in 1979 when 11 desert bighorn sheep from Arizona were released in Devil’s Canyon. Subsequent transplants occurred in 1980 with 16 sheep in Monument Canyon; 1981, nine sheep in Devil’s Canyon; and 1995, 22 sheep in Knowles Canyon.

“When (District Wildlife Manager) Paul Creeden did his masters thesis on the herd in the 1980s, there were no sheep west of Mee Canyon,” Duckett said. “Now, they’ve expanded out into Utah.”

Although the local habitat was suitable for desert bighorn, in several cases the newly relocated sheep, uneducated about the terrain of slickrock canyons, found themselves rimmed out on steep canyons.

On at least one occasion, sheep were found dead at the base of the cliff from which they evidently fell or leapt, trying to escape.

Hunting has always been part of the management plan.

The relocations and the major part of sheep management for the Black Ridge herd are funded by sportsmen’s dollars from the sale of fishing and hunting licenses.

The Division of Wildlife stopped hunting the Black Ridge herd from 1997–2006 after a “dramatic decline” in sheep numbers, possibly due to disease, according to a 2006 report.

Sheep numbers had declined to an estimated 50 animals.

The herd has since recovered and hunting resumed in 2007 with one ram license. That increased to three in 2008 and 2009 and five this year.

“The sheep are occupying all the range from the monument to the state line,” Duckett said. “They’ve become really good at pioneering into good habitat areas.”

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Range makes Black Ridge herd distinctive

The ongoing study of desert bighorn sheep in the Black Ridge herd indicates the animals don’t intermingle with the desert bighorns in the Dominguez-Escalante canyons herd, which can often be seen along Colorado Highway 141 in Unaweep Canyon.

“They are two distinct herds with little interplay,” said Stephanie Duckett, terrestrial biologist with the Colorado Division of Wildlife. “The Black Ridge herd really doesn’t range east of the monument.”

One reason might be the tree-covered terrain between Colorado National Monument and Highway 141 makes it easy for a predator to ambush a sheep.

One ram attempting to expand his range into Bangs Canyon was killed by a mountain lion within days of leaving the monument.

The rough canyon country makes it difficult to manage the Black Ridge herd. The slickrock canyons give sheep plenty of hiding places, making population estimates nearly impossible.

Habitat manipulation also is difficult because much of the herd’s range is in the Black Ridge Wilderness Area.

Fire control and human access are about the only options left to the U.S. Bureau of Land Management, said Heidi Plank, wildlife biologist for the BLM’s Grand Junction Field Office. This office oversees the Black Ridge area and McInnis Canyons National Conservation Area.

“There’s not much we can do in the wilderness area but (elsewhere) we have a fire management plan of trying to suppress fires below a certain elevation because of cheatgrass issues,” Plank said. “This (early lambing) study has us taking another look at that.”

She also said the early lambing might mean changes in seasonal access closures aimed at protecting sheep during this critical period.

— Dave Buchanan


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