Bringing Back the Bighorns: The Hells Canyon Initiative

The area is vast, rugged and spectacular; an imposing, primitive landscape, twice the size of Yellowstone National Park. Eight hundred bighorns are estimated to live here, scattered in 15 different herds, but that is probably just a fraction of the numbers that once inhabited Hells Canyon. "The thing that's really exciting about Hells Canyon is how much potential sheep habitat is here. There's literally over a million acres of sheep habitat. The area can support thousands of sheep and did in the past," according to Frances Cassirer, Idaho Fish and Game research biologist and the tri-state coordinator for the Hells Canyon Initiative. In the mid 1990's, the three states that share the canyon_Idaho, Washington and Oregon_along with the U.S. Forest Service, the Bureau of Land Management and the Foundation for North American Wild Sheep (FNAWS) launched an ambitious project called the "Hells Canyon Initiative". This is an effort to restore wild sheep to their historical abundance and gain further knowledge of the factors that affect bighorn populations throughout North America. "We're collecting information on density, nutrition, pathogens_in other words, diseases. We think that diseases play a really large role in regulation of bighorn sheep, which is unusual" in wildlife populations, Cassirer said. "Most of the time as biologists we look at habitat, predation, weather or some combination of those as what regulates the population. And that certainly may be true in sheep. But we think that perhaps disease, rather than being a consequence of habitat, might actually be a primary player. So, that's what we're trying to find out." Scientists believe that before white settlers arrived, the canyon supported thousands upon thousands of wild sheep. It is ideal habitat, and evidence of their abundance is etched onto the canyon walls. Bighorns are the most commonly depicted animal in the ancient rock art scattered throughout the area. Many Hells Canyon archeological sites yield more wild sheep bones than any other animal. But in recent times the bighorn population has struggled. Outbreaks of pneumonia, thought to be caused by a bacteria, have haunted the Hells Canyon wild sheep triggering seven epidemics. Agencies and sportsmen responded to this threat with a habitat management plan that eased some of the potential conflict between livestock and the wild sheep. In addition, these groups worked together to control noxious weeds and acquire habitat. Then, under the Hells Canyon Initiative, wild sheep were transplanted from Canada as part of the long term plan to boost bighorn restoration. Since 1997, through the combined efforts of three states, two countries and hundreds of individuals, more than 100 bighorns have been relocated in Hells Canyon. Transplants have been funded and supported by conservation organizations such as the Oregon Hunters Association and FNAWS. "We look at it as a natural experiment, this restoration. That's why we're keeping such close tabs on the sheep. So we want to know, of course, if we're successful. And if we're not successful, we want to know why so that we can move forward with our knowledge about sheep and get better at it next time," Cassirer said. The idea behind the research is to compare herds doing poorly with those that are thriving. Some herds, like the group located a mile or so from Pittsburgh Landing, appear to be flourishing. These are the sheep that were brought in from Canada during the winters of 1998 and 1999. All of the transplanted sheep were fitted with radio collars, allowing biologists to keep track of the animals and their movements. Twenty-one bighorns were originally transplanted to this area but by the summer of 2000 there were 50. "We're watching the ewes and lambs and we monitor the health of all the lambs, particularly those with the marked ewes," Cassirer said. A critical component of the research is to evaluate both adult and lamb survival. Studies have shown that the number of lambs surviving the summer can often determine the difference between an increasing or declining population. So, after lambing, each group of ewes and lambs are checked twice a week, a labor-intensive undertaking. "They've had really good production. Most of the ewes have lambs and so it looks like in a few years we should have 100 sheep here, Cassirer said. Cassirer and her staff also record the total number of sheep, their activity and herd composition_how many ewes, lambs and young rams make up the group. Then they plot the location on a topographical map. The same information is collected on each herd to see what may be different. The challenge will be to determine how those differences may affect the health of the herd. Unlike this group, some of the other herds have poor lamb survival and are only increasing at three to four percent a year. "You would think that when sheep are being restored to vacant habitat, the population should be growing at 10 to 15 percent. So, it's been an on-going problem throughout North America that the sheep herds are not increasing as fast as they could. That's why we're looking at this problem very carefully here to see what the causes are and some of the solutions," Cassirer said. In the fall and winter monitoring slows, but biologists still check the herds regularly. This is the breeding season and rams are on the move, looking for receptive ewes. Unlike bull elk, bighorn rams do not form and protect a "harem". Rather, they choose an individual ewe in a group and begin herding her, guarding her from the attentions of other suitors. The pageantry is as old as the sheer basalt cliffs that form the canyon. It is wildlife watching at its best, and even the scientists like Cassirer are caught up in the show. "They just have a charisma. I'm not sure you can really explain it, but it certainly is true. I've never worked with a species that has a following like bighorn sheep."