The Clark Fork River-Grass Valley IBA encompasses about 35 km of river corridor and adjacent uplands between Missoula and Huson. The site supports a high diversity of birds, including a number of species of conservation priority. Habitats include cottonwood gallery forests, riparian willows, various wetland types, grasslands, woody draws, and agricultural crops and pasture lands. Most of the land within the IBA is privately owned.

The IBA is close to Missoula, and birders have been aware of the habitat and wildlife values at this site for many years. Since 2000, Five Valleys Audubon Society has been working with Five Valleys Land Trust to increase awareness within the community about the importance of this area to birds and other wildlife and about its vulnerability to development. Many conservation opportunities exist, ranging from habitat management to establishment of conservation easements. The pressing threats of development and habitat loss give urgent priority to conservation actions.
A brochure that describes the project in more detail is available at

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Ornithological Summary

More than 230 species of birds have been documented in the area since the late 1990s. Species of Continental concern that nest here include Bald Eagle, Peregrine Falcon, White-throated Swift, Lewis's Woodpecker, Red-naped Sapsucker, and Willow Flycatcher. The number of Lewis?s Woodpeckers that we detected (41 pairs per year for two years) exceeds the threshold needed for the site to qualify as an IBA of Continental significance, and the number of Red-naped Sapsuckers (24 and 34 pairs) approaches the threshold. Given that we surveyed less than half of the riparian cottonwood forest, we estimate that the entire IBA supports at least 80 pairs of Lewis's Woodpeckers and more than 60 pairs of Red-naped Sapsuckers.

In addition, significant numbers of transient shorebirds use the area as shown by a 7-year shorebird survey (2000-2006) conducted at the settling ponds on the Smurfit-Stone Container Corporation plant near Frenchtown. The survey documented 28 species; maximum counts on a given day ranged from 81 to 306 in spring and 117 to 1,300 in fall. Sizable numbers of waterfowl also use the IBA year-round. At the Smurfit-Stone plant, 500 to 1,500 ducks and geese occur regularly, with peak numbers exceeding several thousand birds during migration.

Conservation Issues

Major threats to the area include loss of habitat and open space from an increasing number of residential homes and housing developments, and proposals for commercial activities on private lands within the IBA. Noxious weeds are also a problem throughout the river corridor.

Despite these threats, formal identification of the IBA is already making a difference in how the land is being managed and valued by the community. For example, Missoula City and County planners have adopted the IBA boundaries into their respective databases for consideration of proposed development actions, and they alert Five Valleys Audubon of proposed actions and invite comment. Moreover, testimony about the IBA presented at County Commissioner hearings has helped to pass an open space bond and to prevent a large gravel mining operation that had been proposed within the IBA's borders.


Most of the IBA is privately owned, with many small parcels and well more than 100 different individuals involved. State lands include a State Park and two large fishing access sites. The US Forest Service land is a small parcel within one of the fishing access sites. A prominent feature is the Smurfit-Stone Container plant along the Clark Fork River. The holding ponds at the plant support large numbers of migrating shorebirds, and a marshy wetland has been restored specifically for wildlife habitat.


The focal habitats for the IBA are cottonwood/willow riparian forest, grasslands, and wetlands. Much of the cottonwood habitat is intact, whereas the grasslands and wetlands have been heavily disturbed by overgrazing, invasion of exotic species, and cultivation.

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