Birders hopeful for return of swallows to Petaluma bridge

A long-running battle between bird lovers and bridge builders is coming to a close this month as major work on the Petaluma River Bridge, a popular cliff swallow nesting ground, is ending.

At a press conference last week, Caltrans said it plans to wrap up construction on the west side of the span by the beginning of April, leaving the $130 million newly widened bridge free for bird nesting.

“We look forward to completing the necessary construction activities in the vicinity of nesting locations over the next two weeks, and we anticipate leaving the entire bridge open for nesting by the end of March, weather permitting,” said Robert Atanasio, a senior biologist for Caltrans.

The controversy arose in 2013, when Caltrans launched the project to replace the 60-year-old twin-span Petaluma River Bridge with a six-lane span, part of the effort to widen Highway 101 through Sonoma and Marin counties and alleviate traffic.

During the first year of the project, Caltrans contractors placed nets under the bridge to keep the migratory cliff swallows from nesting in the construction zone. But the federally-protected birds, which return each spring from South America to build their conical mud nests, became trapped in the netting, and dozens were killed.

Wildlife advocates sued Caltrans to force the transportation agency to change the methods it uses to exclude birds from the construction site.

The lawsuit was eventually settled out of court, though the Animal Legal Defense Fund and the law firm Meyer, Glitzenstein and Crystal, compelling Caltrans to erect hard plastic sheeting over portions of the bridge to keep the birds away. In addition, Caltrans was required to keep biological monitors on site during construction and scrape nest starts.

Assemblyman Marc Levine, D-San Rafael, passed a bill that required Caltrans to meet periodically with environmental groups and receive feedback on the efforts to protect birds. Caltrans has reported that it has cost $5 million for bird monitoring, legal fees and staff time dealing with the bird issue, including public outreach.

“Any cost of monitoring is far better than the cost of having the project held up,” Levine said.

The wildlife groups, including Sepastopol-based Native Songbird Care and Conservation, the Center for Biological Diversity and a coalition of Bay Area Audubon groups, said they are hopeful that Caltrans will be out of the nesting zone this spring and that the colony of some 800 cliff swallows would resume nesting under the new bridge.

“I remain cautiously optimistic,” said Veronica Bowers, executive director of Native Songbird Care and Conservation.

Cliff swallows are protected under the federal Migratory Bird Treaty Act. C.C. Myers Inc., the contractor that installed the nets three years ago, was fined $3,525 by the U.S. Fish and Wildlife Service for harming the swallows.

The wildlife advocates said they were happy with Caltrans bird protection measures in 2014, but last year had several concerns after a handful of cliff swallows were found dead at the base of the bridge.

Susan Kirks, past president of the Madrone Audubon Society, said she independently monitored the bridge construction last year and observed contractors scraping completed nest that she said contained birds, as opposed to the “nest starts” that would discourage the birds from settling in the construction zone.

Kirks said that, on one occasion, she observed a pair of adult cliff swallows “dive bombing” a biologist and a contractor as they attempted to scrape what was presumed to be inactive nests.

“From our perspective, the cliff swallow behavior represented that the biologist and contractor were in an area of active nests,” she said in an email. “This was deeply concerning.”

She said that the efforts on the part of the wildlife groups were not meant to derail the bridge project, but rather were designed to protect the cliff swallows.

“Our coalition was never opposed to the new Petaluma River Bridge construction,” she said. “Our litigation and subsequent settlement agreement were all motivated to ensure that this longstanding nesting site for migratory birds was protected, and practices to ensure that were put in place and carried out during the construction process.”

(Contact Matt Brown at

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