San Mateo County Birding Guide by Sequoia Audubon Society - Printed on October 30, 2026
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Belmont Slough refers to an area an inlet from the bay, that forms the boundary between Foster City to the north and Redwood Shores to the south. Birders use the name generally to refer to the south side of the slough, and the areas around the Oracle campus and the Hotel Sofitel. There are numerous walking trails in this area, including that of Marine View Park along Oracle Parkway.
Oracle has a pond in front of its six-building complex that is rich in water birds. The entire complex is nicely landscaped with water features and trees that attract passerines. A walk around the pond can be very rewarding, with Great and Snowy Egrets, and Green and Black-crowned Night Herons on its rock edges, along with Spotted Sandpiper. Ducks include Hooded Merganser, Greater Scaup, Ruddy Duck, Mallard, and Bufflehead. American Coot, Pied-billed Grebe and Double-crested Cormorant round out the usual visitors. The trees along Marine Parkway and in the adjacent parking lots attract woodpeckers and warblers.
From Oracle, one can walk across Marine Parkway to Redwood Shores Lagoon. At its head is the Hotel Sofitel. This area was heavily visited by birders in late 2008 for its Long-tailed Duck. Black-crowned Night Herons roost in the trees in the plaza; if you see bird poop, look up and see how many herons you can find in the trees. Birds in the water and along the shores are similar to those in the Oracle pond, with the addition of gulls, scaup, Brown Pelican, Clark's and Eared Grebes, and Belted Kingfisher.
Around the back of the Sofitel is a short section of the Bay Trail that follows both sides of a slender feeder slough, hosting egrets and sparrows.
Crossing back over to Oracle, one can walk or drive Oracle Parkway around this expansive tech campus. The park along the outside of the loop road is called Marine View Park. This provides your first sight of Belmont Slough from the south side. You'll start adding shorebirds to your list, like American Avocet, Black-necked Stilt, Black-bellied Plover, Marbled Godwit, Whimbrel, Willet, and Long-billed Dowitcher. Many of these birds particularly like the pocket of the slough that dead-ends between Oracle Parkway and the Redwood Shores Library. One interesting hybrid duck likes it here too: a Northern Shoveler x Gadwall male, first seen in fall 2008, which returned in fall 2009 (see picture below). As one continues along the slough, other ducks appear in winter and early spring: Northern Pintail, large flocks of Greater Scaup, Gadwall, and more Buffleheads.
Past Island Dr., the path splits. The outer levee path continues along the edge of the Slough, and the inner path parallels Barnegat Lane, which has some parking areas. Between the paths is a tidal pond that fills with shorebirds at high tide (similar to Frank's Dump in Hayward [Alameda County]). This area is directly across from Sea Cloud Park in Foster City.
Beyond Shell Parkway, Marine Parkway becomes Shearwater Parkway. At this point, the levee trail is closed for improvements, although people still use it outside of working hours. The trail continues on around the western edge of Belmont Slough, then turns east again along the bay, with a spectacular view of Bird Island, which is inaccessible. It is possible to reach this view point by car by continuing on Shearwater Parkway, turning left on Canvasback Way, which dead-ends at Seabrook Court. At the intersection and at either end of Seabrook Ct., are viewing platforms allowing one to look over the levee at Bird Island. Birds on the levee include Black Phoebe, Say's Phoebe, European Starling, and sparrows: White-crowned, Golden-crowned, Song, and Savannah. Birds of Bird Island include White-tailed Kite, Red-tailed Hawk, Peregrine Falcon, Northern Harrier, Great Blue Heron, and rarely in winter, the prize of a Short-eared Owl. The mudflat around the eastern platform is a favorite with Killdeer and Least Sandpiper.
The trail, now marked as the San Francisco Bay Trail, continues to Radio Road (see separate entry).
Another productive location in the area is south of the Ralston Avenue exit. Take Ralston Avenue exit east, then turn right on Shoreway Road, then left on Sem Lane. There is a public access trail here. Ron Thorn found a Gray Flycatcher and a Vesper Sparrow on this trail in September 2006.
Canada Goose, Blue-winged Teal, Gadwall, American Wigeon, Mallard, Cinnamon Teal, Northern Shoveler, Northern Pintail, Common Goldeneye, Barrow's Goldeneye, Green-winged Teal, Canvasback, Ring-necked Duck, Greater Scaup, Lesser Scaup, Surf Scoter, Bufflehead, Hooded Merganser, Common Merganser, Red-breasted Merganser, Ruddy Duck, Pied-billed Grebe, Eared Grebe, Horned Grebe, Clark's Grebe, Western Grebe, American White Pelican, Brown Pelican, Double-crested Cormorant, Brandt's Cormorant (very rare at this location), Pelagic Cormorant (very rare at this location), Great Blue Heron, Great Egret, Snowy Egret, Green Heron, Black-crowned Night-Heron, Turkey Vulture, Osprey, White-tailed Kite, Sharp-shinned Hawk, Cooper's Hawk, Northern Harrier, Red-tailed Hawk, American Kestrel (unusual here), Merlin, Peregrine Falcon, Ridgway's Rail (uncommon here), Virginia Rail (rare here), Sora (uncommon here), American Coot, Black-bellied Plover, Snowy Plover, Semipalmated Plover (fall migration), Killdeer, Black-necked Stilt, American Avocet, Spotted Sandpiper, Greater Yellowlegs, Lesser Yellowlegs (uncommon), Willet, Whimbrel, Marbled Godwit, Red Knot (unusual), Sanderling (one record, rare here), Western Sandpiper, Least Sandpiper, Dunlin, Long-billed Dowitcher, Short-billed Dowitcher, Long-billed Curlew, Red-necked Phalarope (fall migration), Red Phalarope (unusual), Short-billed Gull (unusual at this location, winter), Ring-billed Gull, California Gull, Glaucous-winged Gull, Western Gull, Herring Gull, Forster's Tern, Elegant Tern, Least Tern (very unusual at this location), Caspian Tern, Black Skimmer (rare at this location), Rock Pigeon, Eurasian Collared-Dove, Mourning Dove, Short-eared Owl (rare at this location, winter), White-throated Swift, Anna's Hummingbird, Allen's Hummingbird, Belted Kingfisher, Nuttall's Woodpecker, Downy Woodpecker, Northern Flicker (rare here), Black Phoebe, Say's Phoebe, Hutton's Vireo (unusual at this location), Cassin's Vireo (uncommon at this location), Loggerhead Shrike (very unusual), California Scrub-Jay, Steller's Jay, American Crow, Common Raven, Northern Rough-winged Swallow, Tree Swallow, Violet-green Swallow, Cliff Swallow, Barn Swallow, Chestnut-backed Chickadee, Oak Titmouse (uncommon at this location), Bushtit, Wrentit, House Wren, Bewick's Wren, Marsh Wren, Ruby-crowned Kinglet, Hermit Thrush, Varied Thrush, American Robin, Northern Mockingbird, Western Bluebird, European Starling, Cedar Waxwing, American Pipit, Orange-crowned Warbler, Yellow-rumped Warbler, Townsend's Warbler, Common Yellowthroat, Yellow Warbler, Western Tanager, California Towhee, Chipping Sparrow, Fox Sparrow, Savannah Sparrow, Song Sparrow, Lincoln's Sparrow, White-crowned Sparrow, Golden-crowned Sparrow, Dark-eyed Junco, Red-winged Blackbird, Western Meadowlark (uncommon at this location), Hooded Oriole, Brewer's Blackbird, Brown-headed Cowbird, House Finch, Pine Siskin, American Goldfinch, Lesser Goldfinch, House Sparrow
In this guide, "rarities" are defined as those species given an County Abundance Code of 4, 5, or 6.
Cackling Goose, Greater White-fronted Goose, Ross's Goose (2000), Eurasian Wigeon, Black Scoter (2016), Long-tailed Duck, Redhead (2004), Gadwall x Northern Shoveler (hybrid, 2008-2010), Common Gallinule, Swainson's Hawk (2008 fly-over), Short-eared Owl, Gray Flycatcher (September, 2006), Palm Warbler, Lapland Longspur (1991), Brewer's Sparrow (October, 2011), Vesper Sparrow (September, 2006), Lark Sparrow (August, 2011, along Park Preserve behind the school), White-throated Sparrow (2006)
From southbound 101, take the Ralston Ave exit, 412, turn left and cross over the freeway. The road name changes at once to Marine Parkway. For Oracle, turn left on Oracle Parkway, and left into a Public Shore parking area. For Redwood Shores Library, continue on Marine Parkway to Bridge Parkway, turn left onto Bridge, then turn left into the library parking lot. The levee can be accessed from directly behind the library.
From northbound 101, take the Marine Parkway exit, #412.
None
24/7 accessibility
Currently (May 2010), there is construction on the levee north of Shearwater Parkway. The levee is closed to the public, but the closure is realistically only during working hours. Users just step over a downed barrier.
In circumnavigating Oracle Parkway by car, one must take care not to hit the large flocks of Canada Geese that wander in the road. The question of whether searching for the rare goose in the flock increases or decreases your chances of hitting a goose is in need of more empirical research.
There is a public restroom at the Public Shore parking at Oracle Parkway and Shoreway. There is a public restroom along the east side of Oracle Parkway. There are restrooms in the library. The library also has a small snack bar.
Restaurants, gas, and convenience stores are abundant on the west side of US 101.
There are four eBird hotspots dedicated to this area: "Belmont Slough," "Redwood Shores Public Library," "Oracle Pkwy and pond," and "Redwood Shores Lagoon." Together these hotspots have data for twenty-four of forty-eight quadrants, accounting for 123 species. There are very few entries outside of the fall and winter seasons. Don't forget to use eBird to help build a reliable data base of sightings for this valuable eco-system, wedged as it is in the midst of human populations, industrial development, and highways.
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