Along Oakland's San Leandro Bay, the Golden Gate Bird Alliance's Bay Birding Challenge documented a black rail at Arrowhead Marsh — a 72-acre wedge of restored wetland hemmed in by the Oakland Airport, I-880, and the Coliseum, carved out of what was once 1,800 acres of tidal marsh.

On Swan Way in Oakland, there are no swans. There's the Oakland Airport, a pair of budget hotels, an office park, and a road that delivers you — if you know to keep driving — to the fenced edge of Arrowhead Marsh, a protected strip of wetland in the San Leandro Bay that most commuters on 880 have never noticed.

What's behind that fence used to be something much larger. In 1938, San Leandro Bay held 1,800 acres of tidal marsh, designated a state wildlife reserve. By 1986, according to the Golden Gate Bird Alliance's own documentation of the site, just 76 acres of tidal wetlands remained — the rest converted to make room for the Oakland Coliseum, Interstate 880, and the Oakland Airport. When the Port of Oakland proposed taking more seasonal wetlands that same year, GGBA sued and spent a decade in court, ultimately securing a settlement that restored 72 acres of tidal habitat in San Leandro Bay and deeded them to the East Bay Regional Park District. The organization has monitored the site ever since; their current conservation page lists more than 90 bird species, including the federally endangered Ridgway's Rail.

On April 25, Whitney Grover, director of conservation for the Golden Gate Bird Alliance, was walking that fence line with three other birders when she stopped cold. From a distant bundle of marsh grass came a call: kik-kik-kik-kurrrrr. She recognized it immediately — a black rail, one of the most endangered marsh birds left in the Bay — and raised her phone to record it without taking her eyes off the brush.

The outing was part of the GGBA's Bay Birding Challenge, an annual "Big Day" competition in which teams of three to ten birders race to document as many species as possible across the Bay from dawn to dusk — the 2026 edition fell on April 25, per the GGBA's Birdathon event page. Nine teams competed. Grover's foursome — which included photographer Lisa Bach, journalist Lisa Morehouse, and El Cerrito-based landscape architect Tara McIntire — had started the morning at Point Pinole, where a bald eagle appeared shortly after sunrise. Arrowhead Marsh was their third stop. The day's route, reported in detail by Gazetteer SF's Eddie Kim, who joined the group, traced the Bay's remaining accessible wetlands in a single arc.

The detection at Arrowhead was auditory only — a call from deep in the grass, no visual confirmation. The black rail is endangered enough that eBird deliberately obscures the location of confirmed detections to limit foot traffic near nesting habitat. A Ridgway's Rail had also been calling earlier, and the group spent time replaying recordings afterward, debating which bird had produced which sound. Merlin, the audio-ID app, called it a Ridgway. Grover was unconvinced.

Later, at Elsie Roemer Bird Sanctuary in Alameda, Grover observed that sand from the artificial Alameda Beach had migrated south over time, raising sandbars and reducing the water depth where shorebirds feed. "Ninety percent of the shoreline all around the San Francisco Bay was filled or degraded," she told Kim. "We've lost all this marshland and beds of eel grass."

What's left at Arrowhead — 72 acres fought for in a decade of litigation, wedged between jet-fuel infrastructure and a parking structure with planes droning overhead — turns out to be refuge precisely because the surrounding sprawl had already taken everything it could. The road keeps its ironic name. The rails keep calling from the grass.