Bighorn Sheep Facts | Canadian Rockies Wildlife Guide
Prior to the mid-1800s, bighorn sheep were abundant throughout the Rocky Mountains, with a range that extended from Alaska to northern Mexico and into the snowfields of Canada. Their population was estimated to be two million, spread among distinct social groups comprising 10 to 100 members. European expansion westward triggered a decline in the species with the popularity of trophy hunting. Then, ranchers began acquiring land in the mountain valleys, degrading wildlife corridors and critical bighorn habitat as they cultivated. The introduction of domestic sheep delivered the final blow. Wild herds had to compete for forage, while contending with disease transmission from invading livestock.
By 1960, numbers were reduced to fewer than 18,000 individuals. Today, bighorn populations have diminished more than 70 percent from historic levels. Despite intensive management and restoration efforts, populations continue to struggle. Research concludes that wild bighorn herds are most vulnerable to pneumonia carried by domestic sheep. Pneumonia outbreaks result in mortality rates up to 90 percent. Conservationists agree that the separation of domestic and bighorn sheep is vital to ensuring bighorn herd health. This can be achieved through enacting buffer zones, endorsing public policies, working with private landowners and increasing public education about the risks of contact between species.