Birding At the Site

Make an immediate right after entering the park and park in one of the spots which will now be on your left. The trees throughout the picnic area can be good for Yellow-billed Magpie, though they are more often seen than heard. In winter this area can also be good for Western Bluebird and Dark-eyed Junco. Also, be sure to check the liquidambar trees near the NW corner of the picnic area for both expected goldfinches and Pine Siskins (uncommon in winter).

As you continue walking west toward the nature area you will pass under a railroad trestle. Just beyond the trestle is The Bicentennial Grove, a group of redwoods planted in honor of past presidents. It is always a good idea to make a quick check of the grove: in December 2015 two Red Crossbills were seen foraging at the top of one of these trees.

Continue past the grove and you will come to the nature area. After you pass through the gate the trail splits. Continue straight or make a left to walk the loop trail or take the fork to the right to view the Riverbanks sewage ponds. (There is usually a cable across the road toward the ponds here and a sign warning that pedestrian traffic is prohibited, the cable can easily be stepped over and the sign only applies to days when the overflow parking lot is being used.)

You can walk the entire fence along the northern park boundary, occasionally stopping to scan the ponds, but when you reach the west edge of the park you would either need to turn back and walk back to the overflow parking lot or walk downhill to the trail. The hillside here can be treacherous as there are many ground squirrel burrows and the occasional piece of debris hidden in the tall grass. The ponds at the east end of the facility are closer to the fence, making them the easiest to view. The most common bird on the ponds is American Coot, and in summer the pickings can be rather slim, but in winter the numbers of gulls and waterfowl can be enough to keep you busy for a while. Most of the water birds listed at the end of this entry occur on the ponds, Wood Duck, Common Merganser, Green Heron and Belted Kingfisher are more often seen on the river and Great Egret may be seen in both areas.

The loop trail can be birded either clockwise or counterclockwise, but this description follows the latter. Going straight at the fork will take you through the edge of the riparian area. This section of the trail is higher than the section along the river and affords a view into the canopy of the oaks. Tree birds including woodpeckers, vireos (in season), California Scrub-Jay, Tree Swallow (summer), Oak Titmouse, White-breasted Nuthatch, Bushtit, Cedar Waxwing (winter), warblers, Western Tanager (migration), Black-headed Grosbeak (summer), orioles (summer) and finches can often be viewed here without straining your neck because they are usually closer to eyelevel.

As the trail makes its gradual descent as you continue west you will come to the group campsite and one of the pit toilets. In the area near the pit toilet you will pass a few tree tobacco bushes where hummingbirds are quite common. A bit further along are some almond trees where a Gray Flycatcher was seen in May of 2015. White-throated Swifts roost, and possibly nest, where Patterson Road crosses the railroad tracks nearby in Riverbank and can often be seen foraging over the park and this area and the area along the north fence offers the best viewing.

Beyond the almonds you pass the second park host campsite (the first being at the east end of the park) and the trail curves toward the river. From here you can easily walk to the western park boundary and look over the barbed wire fence to bird the undeveloped property beyond. The area beyond the fence is not open to any kind of activity and there are many “No Trespassing” signs posted. Great Horned Owls have nested in the large oaks just beyond the fence; if you find a nest please make your observations brief so as not to disturb the birds unnecessarily. Just beyond the fence at the NW corner of the park there is a large dead snag that is sometimes used by American Kestrel and/or Lewis’s Woodpecker (rare). Say’s Phoebe can also sometimes be found in this area during winter.

From this point on the trail follows the river. There are a few volunteer trails that lead to the water and these can reward a birder with a few extra species, but you should use caution as these trails are rather steep and, if the river is high, can be flooded. It is always a good idea to take advantage of the numerous areas overlooking the river, though. Wood Duck, Common Merganser, Green Heron, Belted Kingfisher and Northern Rough-winged Swallow can sometimes be seen here, and Phainopepla can sometimes be seen in the large, mistletoe-laden cottonwoods on the far bank.

About 2/3 of the way back to the start of the trail you will pass another pit toilet and then come to what can often be the best part of the trail, bird-wise. The thicker understory here offers protection for ground and brush loving birds such as wrens, Hermit and Varied (rare) thrushes, Spotted and California Towhee, Fox, Song, Lincoln’s (winter), White-throated (uncommon) and White- and Golden-crowned sparrows. A Green-tailed Towhee was found just west of the pit toilet in February 2013 and stayed for over a month.

In fall, when the wild grape vines are covered with fruit this area can be alive with birds: woodpeckers, thrushes, Northern Mockingbird, Cedar Waxwing, Phainopepla, warblers, sparrows, Western Tanager, orioles and finches will all come to either eat the grapes or drink the juice. During spring and fall migration, this area can also be exceptional for flycatchers; Western Wood-Pewee and both Willow and Pacific-slope flycatchers have been seen here.

There are several volunteer trails running north-south between the two sections of the loop trail, as well, so if you hear an interesting bird calling from the other portion of the trail it is fairly easy to reach it without rushing around the entire loop.

No rare species have been reported from the sewage treatment plant as yet but the plant and the park as well, are severely under birded, so who knows what rarities will be found here in the future.