San Mateo County Birding Guide by Sequoia Audubon Society - Printed on January 19, 2025
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ATTENTION: CLOSED, NO LONGER A BIRDING SPOT The Radio Road ponds have been drained due to an avian disease that killed substantial numbers of birds here.
Radio Road is a perpetual favorite among local birders, for its fabulous numbers of waterfowl and shorebirds, and the constant hope, often fulfilled, of rarities. While the best time to come here is in fall, it is rewarding at any season. It is not uncommon to see over 10,000 birds from the security of your car, all close enough to be identified with binoculars (although a scope is a spectacular asset at this location).
Radio Road has it all: easy access, constant numbers of birds, rarities, opportunities for study of breeding and of vagrancy, a variety of habitats in a small space, no barriers for those with disabilities, and, for birders who have canine companions, there is a dog park right here!
The main show can be viewed at the outlet ponds connected to the water-treatment plant. There are two large ponds. The southeastern one (the one directly in front of you at the stop sign) is generally more productive; it features two small mud islands, and a long mud bar that attracts shorebirds and provides cover for the three teal species that occur here. You can pull up alongside this area and bird from your car; birds tolerate cars as blinds, and are less likely to be frightened by a scope out of a car window than a birder approaching on foot. You can also park in the area by the dog park, and approach the pond on foot, or scope from across the street. The mud islands serve as roosts for terns; Black Skimmers are regular here (the only reliable site in the county for this spectacular species), and the rare terns - from the expected Common Tern in fall to the once-in-a-century appearance of a Gull-billed Tern in 2009 - should be searched for amidst the many Forster's Terns. Shorebirds, as mentioned, enjoy the long mud bar, and the shallow waters near it. Search the full length of the mud bar. Also, take a look through the often huge flocks of expected shorebirds in winter. Birds like Willet, Marbled Godwit, Long-billed Dowitcher, and Least Sandpipers, can build up to numbers here approaching four figures. It is worth sorting through them to see if a Stilt Sandpiper, Red Knot or Semipalmated Sandpiper is associating with them. In fall and winter, the duck species on the water in this pond can easily total a dozen species. Expected waterfowl include impressive numbers of American Wigeon, Gadwall, Mallard, Canvasback, Northern Shoveler, Northern Pintail, Green-winged Teal, Cinnamon Teal, and Ruddy Ducks. Eurasian Wigeon, Barrow's Goldeneye, Redhead, and some interesting hybrid ducks have been reported from Radio Road. Flocks of Canada Geese can be in the area, too; check them for Cackling Geese and other unusual guests. On the far eastern edge of the pond, there is a heron and egret rookery; Black-crowned Night-herons are year-round residents, too. In spring and summer, Radio Road attracts swallows; in fall, look for migrant sparrows and blackbirds.
The two ponds are separated by a large berm that hosts gulls, usually of at least three species in winter (California, Ring-billed, and Glaucous-winged); some unusual species have turned up here. The northerly pond has a large Forster's Tern roost in summer, and should be checked for waterfowl and shorebirds. It has not had the consistent record of rarities that the south pond has.
Back at the dog park, check the areas with the low vegetation for migrant sparrows and blackbirds. Brewer's, Clay-colored, and White-throated Sparrows, Yellow-headed Blackbird and Great-tailed Grackle have all chosen this small patch of ground during migration. Next, head up to the berm to the south. From this vantage, you can look across the channel known as Steinberger Slough to Bair Island. With a good scope you should be able to spot a Northern Harrier (or, if you get lucky, a Short-eared Owl) harassing the harvest mice on Bair Island. Walk east toward the bay on the berm. Along the shore look for shorebirds and waterfowl: Long-billed Curlew, Western and Clark's Grebes, Brown Pelicans, and flotillas of Scaup can be seen along this walk. At the end of the walk, there is a deck that allows you to scope the mud islands across the outlet of Steinberger Slough on the northeast spit of Bair Island. This can hold more species of terns, shorebirds, and gulls. In front of you, a fenced off area provides excellent habitat for Clapper Rail; you can hear them at dawn and dusk. There could well be other rail species there, too.
There is some construction planned for this area in the Winter of 2009-2010. We will attempt to keep readers updated on this site.
Words alone cannot describe the thrill of a good day at Radio Road. The setting is not scenically beautiful, and between the dog park and the noises from the water treatment plant, this would not seem to be an attractive site for birding. But the proximity of multiple habitats, the approachability of the birds, and the memories that nearly every birder who frequents this spot has - of rarities seen, lifers added, and hope springing eternal - means there is no place like it for learning about birds and birders.
Canada Goose, Gadwall, American Wigeon, Mallard, Blue-winged Teal, Cinnamon Teal, Green-winged Teal, Northern Shoveler, Northern Pintail, Canvasback, Ring-necked Duck (rare at this location), Greater Scaup, Lesser Scaup, Surf Scoter, Bufflehead, Common Goldeneye, Hooded Merganser, Common Merganser, Red-breasted Merganser (uncommon at this location), Ruddy Duck, Wood Duck (rare here), Pied-billed Grebe, Horned Grebe, Eared Grebe, Western Grebe, Clark's Grebe, Brown Pelican, Double-crested Cormorant, Great Blue Heron, Great Egret, Snowy Egret, Green Heron (unusual at this location), Black-crowned Night-heron, Turkey Vulture, Osprey (uncommon), White-tailed Kite, Northern Harrier, Sharp-shinned Hawk, Cooper's Hawk, Red-shouldered Hawk, Red-tailed Hawk, American Kestrel, Merlin, Peregrine Falcon, American Coot, Black-bellied Plover, Semi-palmated Plover, Killdeer, Black-necked Stilt, Black Oystercatcher (uncommon at this location), American Avocet, Spotted Sandpiper, Greater Yellowlegs, Willet, Lesser Yellowlegs, Whimbrel, Long-billed Curlew, Marbled Godwit, Black Turnstone (uncommon at this location), Surfbird (exceptionally uncommon at this location), Red Knot, Sanderling (rare at this location), Western Sandpiper, Least Sandpiper, Dunlin, Short-billed Dowitcher, Long-billed Dowitcher, Red-necked Phalarope, Bonaparte's Gull, Short-billed Gull, Ring-billed Gull, Western Gull, California Gull, Herring Gull, Glaucous-winged Gull, Caspian Tern, Forster's Tern, Elegant Tern, Black Skimmer, Rock Pigeon, Mourning Dove, White-throated Swift (migration), Anna's Hummingbird, Belted Kingfisher, Pacific-slope Flycatcher (migration), Black Phoebe, Say's Phoebe, California Scrub-Jay, American Crow, Common Raven, Tree Swallow, Violet-green Swallow, Northern Rough-winged Swallow, Cliff Swallow, Barn Swallow, Chestnut-backed Chickadee, Bushtit, Marsh Wren, Ruby-crowned Kinglet, American Robin, Northern Mockingbird, European Starling, American Pipit (including an appearance of the rare subspecies from Asia), Cedar Waxwing, Orange-crowned Warbler (migration), Yellow Warbler (migration), Yellow-rumped Warbler (fall-spring), Townsend's Warbler (fall-winter), Common Yellowthroat, Western Tanager (fall migration), California Towhee, Savannah Sparrow, Song Sparrow, Lincoln's Sparrow, White-crowned Sparrow, Golden-crowned Sparrow, Dark-eyed Junco, Red-winged Blackbird, Tricolored Blackbird (rare at this location), Western Meadowlark, Brewer's Blackbird, Brown-headed Cowbird, House Finch, Lesser Goldfinch, American Goldfinch, House Sparrow, Nuttall's Woodpecker
In this guide, "rarities" are defined as those species given an County Abundance Code of 4, 5, or 6.
Greater White-fronted Goose, Cackling Goose, Brant (2013, rare on bayside of county), Red-throated Loon (2013 - odd at this location!), Eurasian Wigeon (annually), Redhead (2012, 2014), Long-tailed Duck (2018, Steinberger Slough mouth), Barrow's Goldeneye, American White Pelican, Cattle Egret, White-faced Ibis (2015), Common Gallinule, White-faced Ibis (2016), Pacific Golden-Plover (2010), Solitary Sandpiper (2002), Pectoral Sandpiper (almost annually), Wandering Tattler, Ruddy Turnstone, Semi-palmated Sandpiper, Wilson's Snipe, Wilson's Phalarope (2015), Franklin's Gull (2015), Thayer's Gull, Glaucous Gull (2011), Least Tern, Common Tern (a few, most years), Arctic Tern (2002, 2015), Gull-billed Tern (2009), Black Tern, Short-eared Owl (2012), Rufous Hummingbird (2015), Dusky Flycatcher (2015), Willow Flycatcher (2012, 2023), Eastern Kingbird (2008, 2018), Western Kingbird (most years in migration), Tropical Kingbird (2012, 2018), Cassin's Kingbird (2011), Loggerhead Shrike (2016, 2017, 2018, 2019), Yellow-billed Magpie (2010), Bank Swallow (2012, 2016, nearly annual in migration), Palm Warbler (2012, 2013), Northern Waterthrush (2013), Brewer's Sparrow (2007), Clay-colored Sparrow (2004), American Tree Sparrow (2010), Vesper Sparrow (2014), Swamp Sparrow, White-throated Sparrow, Great-tailed Grackle (2006, 2011, 2013), Yellow-headed Blackbird (2011, 2012)
Radio Road is located at the northeastern end of Redwood Shores Parkway. From US 101, take exit 411, which has many names, including "Redwood Shores Parkway." Whether exiting from US 101 north or south, follow the small sign that points you in the direction of the small San Carlos Airport; this will put you on Redwood Shores Parkway in the correct direction. Once you are on Redwood Shores Parkway, stay on it for a few miles. When you reach Shearwater Parkway (an optimistically named street!), continue on Redwood Shores Parkway, and look for the tall electrical towers just past a slough on your right. There is a sign there that says "SBSA 1400 Radio Road." Turn right at this sign; you are now on Radio Road. You come to a stop sign; in front of you are the ponds of Radio Road; to your right is the Dog Park; to your left is the left spur of Radio Road; if you take a right, you can reach the main parking for Radio Road (and South Bayside System Authority).
These directions make it sound quite complicated, but it is really quite simple - take Redwood Shores Parkway to Radio Road! The South Bayside System Authority provides a nice map; see link below.
This area is free and open to the public.
24/7
Don't fall into the water: it is wet and has a heritage linking it to a Water Treatment plant. I suppose there might be ticks around, but they can attach themselves to the dogs at the dog park instead of to you. Seriously, this is not a particularly hazardous place!
There are no facilities here. You are not far from the stores at the Nob Hill Market plaza, and the bathrooms at the restaurants there.
If you see a problem that you think needs the attention of the South Bay System Authority, their phone number is 650-591-7121.
Radio Road was a well-visited hot spot in eBird, with 201 species recorded, and entries from all quadrants. Please continue to enter your sightings in eBird. There are numerous hotspots around Redwood Shores, so do attempt to keep entries separate for different locations, but aside from historic records, it is best not to add entries to this hotspot, since the location is officially closed.
Sequoia Audubon Society led six field trips here in the heyday of Radio Road, the early 2010s.
Author: Jennifer Rycenga, Uploaded:
