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A walk here will be productive at any time of year, but the bird list will be highest in fall and winter.

Birding PRBO's New Back Yard

Rich Stallcup

While few places on Earth are as wild in natural scenery, climate, and wildlife diversity as PRBO's long-time headquarters on the east shore of Bolinas Lagoon, the new location at Shollenberger Park, along the Petaluma Slough of northern San Francisco Bay, offers great birding in a peaceful, refuge-like setting.

A two-mile flat loop trail (yes, multi-use, and you will be passed by a few hikers, joggers, and doggers) passes close to several wetland habitat types. There are freshwater ponds with cattail marshes, tidal marshes and mudflats, and a large tidal slough, the Petaluma "River" (designated by Congress in 1959 to make federal funds available for continued dredging of the historic shipping channel).
American Bittern in cattail marsh habitat. Photo by Rich Stallcup.

A walk here will be productive at any time of year, but the bird list will be highest in the fall-through-winter seasons, mid-July to late April. Some of the more shy species, generally coveted as sightings, are most easily detected in spring.

The water ponds and marshes are narrow and run parallel to the trail, so the birds, when seen, are close! These may include Pied-billed Grebe, Green Heron, American Bittern, Mute Swan, Blue-winged and Cinnamon teal, Sora, Virginia Rail, and Common Moorhen. About half the turtles are native western pond turtles, and half are feral red-eared sliders. The large, swimming or munching wild mammals are muskrats.

The tidal mudflats, south of the south berm, are caused by a break in the levee containing Petaluma Slough. There always seem to be a nice variety of shorebirds (often including some rarity like Pacific Golden Plover), ducks, and more swans.

The field and trees, south and east, are attractive to raptors like White-tailed Kite, Merlin, Ferruginous Hawk, and even Golden Eagle. The 230 acres recently purchased from Grays Ranch includes more of these habitats and will soon be open to the public, with another parking lot and trails connecting to the levee.
Seasonal freshwater pond at Shollenberger Park. Photo © Gerald Moore/Petaluma Wetlands Alliance.

The standing brackish pools and islands within the loop are especially attractive to ducks and gulls (of many kinds) in fall and winter, and to Black-necked Stilts, American Avocets, and sometimes Wilson's Phalaropes in summer. When the water levels are drawn down in autumn, Shollenberger can attract many sorts of migrating shorebirds (15-20 species in a given day), which may include uncommon waders like Lesser Yellowlegs, Semipalmated, Baird's, or Solitary sandpiper, or something truly rare like Buff-Breasted or Stilt sandpiper.

Diving ducks seen on the "river" in winter may include Bufflehead, scaup and goldeneye. Night-herons sometimes roost on the retired boats on the far shore. The saltmarsh above the northwest berm is dense Scirpus (sedge) forest and, while not much else may be seen, a Black Rail or two may be heard singing there, crepuscularly, from late February into April.

Getting There: From Highway 101, take the Lakeville Highway/Route 116 exit at the north end of the Petaluma River bridge, and go east one mile to South McDowell. Turn right, pass the big post office building, go over the bridge of Adobe Creek, turn right on City Park, and go 100 yards into the parking lot. There are clean bathrooms there with running water.

Note: Mute Swans are native to Europe but have an established feral population, about 80 birds, that roam around northern Marin and southern Sonoma counties. Most of their nesting takes place at La Laguna off Chileno Valley Road or at Shollenberger Park.