Following I-90 east of Missoula provides interesting birding along the Clark Fork River. Milltown Pond: Take exit 110 on I-90 to Bonner. Where Hwy 200 turns north into Bonner, go east 0.2 miles on the frontage road to the orange Milwaukee Railroad Caboose. Park there and follow the trails down to the river for good riparian birding. Rock Creek: take exit 125.
The slough on the north side of I-90 is good for Wood Ducks, Lazuli Buntings, and warblers. On the south side, follow Rock Creek several miles to Valley of the Moon Campground. Look for bighorn sheep, Wood Ducks, hummingbirds, and other mountain species.
Beavertail Hill State Park: take exit 130 and turn south.
Go one or two miles past the park to a good area for Wild Turkeys. At the park, look for American Dippers, five species of swallows, woodpeckers, Cedar Waxwing, warblers, and Black-headed Grosbeak. Also check the ponds north of I-90.
Bearmouth Canyon: exit at the rest area (near mile 144) and look for White-throated Swifts and Violet-green Swallows that nest on the cliffs just east of the rest area. Parking is illegal along I-90. However, you can take exit 138 to the Bearmouth Chalet and follow the frontage road north of the river into Bearmouth Canyon and on to Drummond for some interesting birding.