Wetlands Walk Trail in Cosumnes River Preserve

Potato-shaped gall growing on valley oak tree

Wood duck illustration on bridge plaque

At the north side of the visitor center of Cosumnes River Preserve is the trailhead for the Cosumnes River Walk and the Wetlands Walk Trail. A bridge with metal plaques on its handrails, illustrating local animals and plants, crosses Willow Slough. Turn left when you get to the open land with rail tracks in view.

Bridge over Willow Slough

Turn left again at the next junction, from where another bridge (see picture) takes you across Willow Slough to an “orchard” of valley oaks: these trees were planted by preserve volunteers in 1988. They are much younger and smaller than the majestic valley oak you will encounter while exploring the River Walk Trail farther south.

At the branches of some oak trees you will notice yellowish brown or dark brown galls—often ball-shaped, occasionally potato-shaped like the one shown above. They develop when wasps lay their eggs in the bark. I saw  numerous valley oak trees with dense clusters of galls. Judging by tree appearance they do not harm the growth or well-doing of the trees.   

The valley oak trees populate most of the area north of the slough between the railroad tracks and Franklin Boulevard. The trail loop intersects with Franklin Boulevard and continues southwest toward the boardwalk and back to the visitor center. At the end of the half-mile-long boardwalk you will find a viewing platform. Wildlife viewing here is most interesting when the ponds are flooded and the area turns into wetland, providing opportunities to see ducks, geese, swans and shorebirds. Wading birds such as ashy gray sandhill cranes with their bare red-topped heads roost in the ponds of the preserve. The significance of the preserve as a crane stop is highlighted by featuring them in the Cosumnes River Preserve logo and in the crane sculpture in front of the visitor center.  

Boardwalk with viewing platform during the dry season