Aggressive gray wolf hunting took a toll in much of the Northern Rockies last year as the predator's population saw its most significant decline since being reintroduced in the region.
Numbers released by state wildlife agencies show Wyoming's wolf population down 16 percent from 2011, Montana's down 4 percent and Idaho's down 8 percent.
That was partially offset by population gains in eastern portions of Washington and Oregon, where wolf numbers have been climbing rapidly over the last few years but still remain low compared to other parts of the region.
Federal wildlife officials are expected to weigh in Friday on whether the population remains sustainable two years after wolves lost their endangered species protections in most of the region.
The government's original recovery goal, set in the 1990s, was at least 300 wolves in the region. Despite last year's decline, the latest figures show the population remains at more than five times that level.
Overall, biologists tallied a minimum of 1,674 wolves across the five states at the end of 2012, a 6 percent decline.
Parts of northern Utah also fall with in the Northern Rockies wolf recovery area, but the state has no wolves.
In Wyoming, wildlife officials this week said the state will halve its quota for the fall hunting season, to 26 animals.
The proposal will be up for public review this spring. It applies only to the state's trophy game areas for wolves in the northwest corner of the state around Yellowstone and Grand Teton National Parks. Elsewhere in the state wolves are designated as predatory animals that can be shot on sight.
By contrast, in Montana and Idaho, wildlife officials have pledged to continue driving down wolf numbers to reduce attacks on livestock and big game herds.
Despite protests from some wildlife advocates, both states contend their wolf numbers remain high enough that there is little possibility of the animals being returned to the endangered list.
Wolves were exterminated across most of the Lower 48 states last century except in the Great Lakes region. The Northern Rockies population has grown from 66 animals reintroduced to Yellowstone National Park and central Idaho in 1995 and 1996. Other animals wandered down from Canada.