We can only infer from anecdotal mortality counts at the beginning of the 20th Century that there once was a large population of grizzlies in the region now bounded on the north by Interstate 90 and on the south by Interstate 84.
The principal river drainages in this region are the Clearwater, which Lewis and Clark called the Kooskooskie, and the Snake, which they named Lewis's River, whose headwaters contained the spawning beds (called redds) of huge migrations of four species of anadromous Salmonids that the explorers first described for scientists.2 The grizzlies thrived on these, along with rodents, berries, tubers and insects between fish feasts; there were no bison or elk in the Bitterroot Mountains.
The main watershed of the Clark Fork of the Columbia is north and east of the Bitterroot Ecosystem. Historically, as far as fisheries biologists have been able to determine, it has never harbored any salmon runs, for the same reason that Lewis suspected--high waterfalls downstream--and there were few if any bison anywhere in it after the turn of the 19th Century. Thus, with better subsistence for grizzlies west of the Bitterroot Divide, it is not surprising that the Corps of Discovery did not encounter any of them in the Lemhi, Salmon, or Bitterroot Valleys, or even among the high mountain ridges where the Indian trail led them.
After the mid-1800s, as settlers moved into the boundary valleys, and with the beaver market diminished since the 1840s, trappers like Lawrence began harvesting grizzlies along with other furbearers--marten, lynx, mink, and ermine. By the early 1900s trappers may have been taking twenty-five to forty grizzlies annually. Meanwhile, trophy hunters entered the scene.
After the huge forest fires of 1910 and 1934 changed the forest face of the Northern Rockies, the Bitterroots became a commercial arena, as thousands of cattle and sheep were grazed on the new ground cover among the burned snags. Naturally, herders perforce armed themselves against the appetites of the grizzlies.In 1910 a dam was built near the mouth of the South Fork of the Clearwater, and in 1927 another was erected near the mouth of the main Clearwater River at Lewiston, Idaho, just above its confluence with the Snake. These barriers virtually closed the Clearwater to spawning salmon. Although the first dam was removed in 1963, and the Lewiston dam in 1973, six new dams on the Snake and Columbia have further inhibited anadromous lifestyles.
In 1971 Dworshak Dam, at the mouth of the North Fork of the Clearwater--almost directly opposite the Corps of Discovery's "Canoe Camp" of September 26-October 7, 1805--closed off 627 miles of salmon and steelhead trout spawning and rearing habitat in the northern third of the Bitterroot ecosystem. Hatchery-bred kokanee, which are landlocked sockeye salmon, have been introduced into the reservoir, with uneven success. In any case, their presence will not serve a grizzly population in the recovery area.
Federal and state hatcheries aim to restore chinook salmon (Oncorhynchus tshawytsha) and steelhead trout (Oncorhynchus mykiss) into the Clearwater drainage, and the Nez Perce Tribe is working to restore fall chinook and coho salmon into the lower Clearwater River drainage.
Driven from the mountains by hunters, and deprived of seasonal salmon runs, the few remaining grizzlies invaded the valley floors, where they were the losers in their inevitable conflicts with humans.
The last grizzly track to be seen in the Bitterroot Mountains was recorded in 1946. That was the first year the Idaho Fish and Game Department prohibited grizzly hunting.
1. Reports of Explorations and Surveys, to Ascertain the most Practicable and Economical Route for A Railroad from the Mississippi River to the Pacific Ocean. Made under the direction of the Secretary of War, in 1853-4, According to Acts of Congress of March 3, 18753, May 31, 1854, and August 5, 1854. Vol. I (1855), Map No. 3.
2. Bud Moore, The Lochsa Story: Land Ethics in the Bitterroot Mountains (Missoula, Montana: Mountain Press, 1996), pp. 265-78.