Bighorn sheep herd rebounding after disease in 1990s
October 23, 2016
LOVELAND, Colo. (AP) — Majestic bighorn sheep deftly dart up and down the steep, jagged walls of canyons throughout Colorado, delighting wildlife watchers when they spot the iconic Colorado animal that, just over a century ago, neared extinction.
With a statewide population of 7,000 bighorns, thanks to decades of work to rebuild the population, big horns cut a prominent profile throughout Colorado’s canyons, including the Big Thompson Canyon west of Loveland.
There, a herd of about 70 sheep thrive throughout the seasons, reported the Loveland Reporter-Herald (http://bit.ly/2evx833).
“It’s definitely one of the most viewed sheep herds in Larimer County,” said Ben Kraft, a wildlife biologist with Colorado Parks and Wildlife.
“It’s amazing how agile they are going up and down those rocks.”
Once prominent throughout Colorado canyons, bighorn sheep populations were decimated by the early 1900s due to diseases from domestic livestock and over hunting, leading the efforts to repopulate. For decades, Colorado Parks and Wildlife and the Rocky Mountain Big Horn Society worked together to rebuild the populations by transplanting sheep from one location to another.
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The first such transplant, from the still popular Georgetown herd, occurred in 1940, according to information on the Colorado Parks and Wildlife website. Since then, more than 100 transplants have taken place, mostly in the 1970s and 1980s, throughout the state.
Twice, sheep have been transplanted to supplement the Big Thompson herd — 26 sheep from the Mummy Range in 1987 and 22 from Georgetown in 2000.
The most recent infusion was to boost the herd after a large die off of all ages of sheep due to pneumonia, likely from domestic sheep, in the late 1990s.
Before then, the Big Thompson herd boasted 150 to 200 sheep. The disease knocked it down to about 100, and now there are even less.
However, despite some lingering effects of the disease and some indication of bacteria from domestic sheep, spread through interactions, documented in the herd as recent as two years ago, Kraft said the Big Thompson herd is considered to be on the rebound.
The biggest sign, he said, is that the ewes giving birth to healthy lambs.
“If we weren’t seeing any, we would be really alarmed,” Kraft added.
Perhaps, he said, another reason the herd is smaller now is due to road construction and development in the Big Thompson Canyon since the 1990s.
“That area may not be able to support as many big horns as it used to because of loss of habitat,” Kraft said.
But the population of 70 seems to be a healthy number, as indicated by births, which is why Colorado Parks and Wildlife issues hunting licenses in the herd, according to Kraft. This year, there were two licenses for ewes and two for rams.
The animals forage on grass, forbes and shrubs year round and can be spotted throughout the canyon in all seasons. They do travel more to the east end of the canyon in the spring and the west in the winter, noted Kraft.
Throughout most of the year, the rams roam in “bachelor bands,” while the ewes and their young group together.
But during mating season, November and December, the dominant rams will join the female herd. Sometimes, the rams even fight each other for dominance, crashing their horns together with force until one ram clearly champions.
“Three years ago, I saw two rams, and they did that for like 25 minutes until one collapsed,” Kraft described. “The other jumped on his back.”
Babies are born from May through July, during which time the mothers move to really steep terrain, like the Narrows, for protection from predators.
The animals are able to dart up steep canyons because of the way they are built. They have small feet, blocky legs and a stout body, Kraft described.
“They’re a lot more compact animal than a deer or an elk,” he said. “They’ve evolved to living in that kind of habitat.”
Several different herds live in Larimer County, including one in the Poudre Canyon, one in the Rawah Wilderness and three in Rocky Mountain National Park. Two combined herds on the west side of the national park are estimated at 300 total animals, while the east-side herd has about 100 animals that live in the Mummy Range area, said Mary Kay Watry, conservation biologist.
The herd on the east side of the park mostly stays within the boundaries, however, some rams do roam and likely interact with ewes in the Big Thompson herd, said Watry, who works for Rocky Mountain National Park.
Wildlife viewing is one of the most popular activities in Rocky Mountain National Park, and big horn sheep are definitely a draw along with many other species, as they are in the Big Thompson Canyon.
“Their majestic appearance, that’s a big drive and symbol of wilderness,” Watry said. “Their agility on rough terrain makes them very impressive to watch and to see.”
Information from: Loveland Daily Reporter-Herald, http://www.reporterherald.com/