Northwestern Montana is the most lushly vegetated part of the state, and its forests, rivers, and wetlands provide homes to a wide variety of birds, fish, and large mammals.
Thanks to the warm wet weather blowing over the mountains of Washington and Oregon from the Pacific Ocean, northwestern Montana’s forests resemble those of the Pacific Coast with their abundance of conifers, including Douglas fir, western red cedar, and western hemlock. Ponderosa pine, lodgepole pine, and western white pine are other Pacific trees that are important to the landscape and economy of western Montana. There’s also a good sprinkling of trees more characteristic of the Rockies, such as Engelmann spruce, western larch, and subalpine fir.
The bitterroot, the state flower, was an important food for the Flathead Indians. It is most abundant in the valley that bears its name, where it flowers early in the summer. Subalpine wildflowers bloom wildly on the mountainsides once the snow has melted. Look for glacier lilies, bear grass, Indian paintbrush, and lupine.
Shrubs tend to grow at lower elevations than the wildflower meadows. Huckleberry bushes run amok in the open areas of northwestern Montana. Look to meadows, old burns, and clear-cuts for the most intense growth. Berries begin to ripen at lower elevations toward the end of July, moving upward as the summer progresses. When in huckleberry country, keep an eye out for bears, which love to feast on the tasty fruit.
Oregon grape and kinnikinnick (whose bark was smoked like tobacco by the Indians) are other common shrubby plants in northwestern Montana forests.
Grizzly bears live in some of the more isolated areas of northwestern Montana, including the Cabinet and Mission Mountains Wilderness Areas . Black bears are more widespread. Don’t mess with either type.
Bighorn sheep can be spotted on steep hillsides throughout the state’s northwestern corner. There’s a special bighorn-viewing area  on Highway 200 just east of Thomspon Falls  and a de facto one along Highway 2 west of Libby. Bighorns also live on the National Bison Range  in Moiese, which is just about the only place in western Montana you’ll see buffalo, except those kept in private herds as ranch stock or a tourist attraction. Elks, white-tailed and mule deer, moose, and mountain goats are among the other ungulates, or hoofed animals, that inhabit northwestern Montana.
Mountain lions once had a reputation for being rather elusive, but over the past few years they’ve been reported to roam the streets of Columbia Falls  and send joggers up trees in Missoula’s  Greenough Park.
There’s an astounding variety of birdlife in northwestern Montana: bald eagles, ospreys, woodpeckers, dippers, Clark’s nutcrackers, western tanagers, great blue herons, hawks, owls, vultures, blue grouse, ruffed grouse, magpies, and hummingbirds. There is a host of waterfowl and shorebirds around Ninepipe National Wildlife Refuge  and Pablo Wildlife Refuge in the Mission Valley. Loons nest in several lakes near Eureka and in the Swan Valley .
There are three major trout species in northwestern Montana: cutthroat, bull, and rainbow. The westslope cutthroat is Montana’s state fish, and while not officially endangered, it is the object of some concern. Catch-and-release fishing is generally recommended — and in some places mandatory — for cutthroat. Bull trout live primarily in the Flathead River system, but their populations have also declined dramatically. In order to protect them from further decline, they are off-limits to anglers on all streams west of the Continental Divide. Rainbow trout are widespread and are especially prolific in the Kootenai River, where they’re native.
Kokanee salmon were introduced to the Flathead system in the 1930s and flourished there for about 50 years. In recent years, Flathead populations of this landlocked salmon have declined precipitously, most likely because of competition with mysis shrimp. Kokanee are still plentiful in other lakes, including Lake Mary Ronan  (west of Flathead Lake ) and Lake Koocanusa.
Dams and development have altered the riparian ecology in northwestern Montana. Native fish, including bull trout, westslope cutthroat, and whitefish, having faced the dams and competition from nonnative species such as lake trout and kokanee salmon, are now seriously threatened by habitat degradation caused by logging. In clear-cut areas, soil and debris erode into streams, muddying the water and disturbing the delicate chemistry the fish need.