NOTE: Please be advised of road closures in the area. Current directions and information can be found at www.cosumnes.org. The preserve will remain open during these closures.
The Cosumnes River is the last free-flowing river coming out of the west slope of the Sierra. A wide swath of the lower floodplain and surrounding habitat is preserved within the more than 45,000-acre Cosumnes River Project south of Elk Grove. A wide variety of habitats can be found, including wetlands, grasslands, wildlife-friendly agriculture, and perhaps the most intact valley oak riparian forest in existence. The preserve is managed by a partnership including the Nature Conservancy, the Bureau of Land Management, Ducks Unlimited, Sacramento County Parks and Open Space, the California Department of Fish and Game, the California Department of Water Resources, and the Wildlife Conservation Board. The preserve is designated as a Globally Important Bird Area, and 300 species have been recorded, including many rarities.
Wilson’s Snipe, Image by Mary Forrestal
Despite its excellent track record, the preserve is under-birded. It is worthy of a visit in just about any season, though things are slower in June and July. For an introduction to the preserve’s avifauna, you can join one of the monthly bird surveys. The visitor center has informative displays, maps, bird lists, and trail guides available. The trails are open from sunrise to sunset, though there is limited parking when the visitor center parking lot gates are closed. For more information visit their website.
This site is an Accessible Birding location. To learn more about the accessibility of this location visit Accessible Birding.
Note: In spring and summer, mosquitoes can be abundant and aggressive. Ticks can also be numerous if you leave the trail. Bring repellent. Mountain lions have been reported on several occasions.
Birding the site: Two trails begin at the visitor center: the one-mile Wetlands Walk and the three-mile River Walk. The Wetlands Walk goes along the Lost Slough Wetlands to the west of Franklin Boulevard. A scope is helpful to spot distant waterfowl. The boardwalk heading west from the Wetlands Walk can be excellent for rails. Sandhill Cranes (late September to early March) are often fairly close to the trail. In spring and summer, Blue Grosbeaks (uncommon) sit up and sing from the low vegetation. Continuing north on the trail, you can cross Franklin Boulevard and loop back to the visitor center via the foot bridge or keep going on the River Walk.
The River Walk begins at the visitor center by crossing Willow Slough on a substantial foot bridge. The bridge provides an excellent vantage point for seeing songbirds in the adjacent riparian vegetation. On the east side of the slough, the wetlands provide good views of waterfowl and other waterbirds. Swamp Sparrows (very rare) have been found here and elsewhere on the wetland edges. For a half-mile, the trail stays near the wetlands, where rails, American Bitterns, and Common Yellowthroats can often be seen or heard.
The trail passes through a mix of habitats, with willow-dominated and oak-dominated riparian forest, and areas of oak savanna. In spring and fall, there can be an excellent movement of songbird migrants. Wrentits call from the underbrush, and in spring and summer the songs of Bewick’s Wrens, Northern House Wrens, and Spotted Towhees fill the air. Several species of eastern warblers have been found along the trail, including Prothonotary and Black-throated Blue Warbler. As the trail reaches the Cosumnes River, it comes to a nice patch of mature valley oaks. The trail will lead you under railroad tracks, through an open section, then close to the river in a forest of medium-sized valley oaks. This area is known as “the Point” and has produced many of the preserve’s interesting records. There are benches next to the river to allow a break from walking. The trail makes a partial loop through grassland and oak savanna, and then backtracks to the visitor center. Despite all that this trail has to offer, there are many mornings when there are no birders to find its avian surprises. The first group out in the morning often flushes several flocks of Wood Ducks and may see river otters and beavers. eBird Sightings - Wetlands walk, Boardwalk, Headquarters, River Walk
Wrentit, Image by Mary Forrestal
Desmond Road is excellent for waterfowl and crane viewing. Mornings and evenings can be spectacular. It goes east from Franklin Boulevard, one mile south of Twin Cities Road or 0.7 mile north of the visitor center. It is one of the better places to find Eurasian Wigeon and often harbors thousands of Greater White-fronted Geese. Check the wetlands on either side of the road and along Bruceville Road going north toward Twin Cities Road. Along Bruceville Road, the large microwave tower often serves as a lookout for a Peregrine Falcon.
To explore the Valensin portion of the preserve to the east of Highway 99, take Twin Cities Road six miles east of Bruceville Road and go north on Highway 99 for two miles to Arno Road. Exit and head east on Arno Road. Dairies along this and other roads in the area can host large flocks of blackbirds, including Tricolored Blackbirds. In 0.4 mile you might want to check the small cemetery on the north side of Arno Road. The old headstones are interesting, and this is a good area to scan the grasslands well away from the road, with its sparse but often speeding traffic. Keep an eye on the grasslands and agricultural lands for raptors, cranes, and Long-billed Curlews. In another 1.2 miles, turn left to stay on Arno Road. Continue north and it will become Riley Road. This section of road has little traffic and allows for more relaxed observations. Near the second creek crossing, look for raised areas to the east of the road that might harbor Burrowing Owls. The grasslands in this area often host Ferruginous Hawks. Horned Lark flocks have contained longspurs. Riley joins Dillard Road, and a left turn will take you back to Highway 99 in 2.7 miles. If you still feel like exploring, head east on Dillard Road beyond the preserve. Between Dillard and Twin Cities Roads, Alta Mesa and Clay Station Roads can be productive for open country birds. Continuing east on Twin Cities Road will take you to Rancho Seco and the Howard Ranch described below.
NOTE: Please be advised of road closures in the area. Current directions and information can be found at www.cosumnes.org. The preserve will remain open during these closures.
Directions: To reach the visitor center, take Interstate 5 about 20 miles south from Sacramento until Exit 498, Twin Cities Road. Turn left and go east on Twin Cities Road for one mile to Franklin Boulevard. At the stop sign, go south for 1.7 miles, and the visitor center will be on your left. Address: 13501 Franklin Blvd.