Caltrans Agrees to Stop Using Bird-Killing Nets

California's transportation agency has agreed to stop using bird netting at its construction sites that ended up killing what may be hundreds of protected cliff swallows at a bridge construction project site in Sonoma County, and the agreement will influence how it conducts its projects elsewhere in the state.

According to an announcement released Thursday, Caltrans will remove netting that was intended to keep swallows from nesting on the Petaluma River Bridge and Lakeville Highway Overpass as the two adjacent Route 101 viaducts are being upgraded.

According to the group Native Songbird Care and Conservation, one of five groups that filed a federal lawsuit in May 2013 to make Caltrans get rid of the netting, more than a hundred cliff swallows had become fatally entangled in the netting by the previous month. With Thursday's settlement, the agency is agreeing to use safer measures to keep nesting birds away from its projects, including scheduling those projects to avoid nesting season.

Cliff swallows are small, gregarious birds that prefer to build their mud-plastered nests on vertical surfaces. Restricted to rock faces before the advent of large construction projects, the birds now frequently attach their nests to bridge abutments and similar structures, especially if -- as is the case with the Petaluma River crossing -- there's a nearby source of water to attract their insect prey.

Best known for their adoption of the mission at San Juan Capistrano as a nesting colony site, the swallows are protected under the Migratory Bird Treaty Act.

As Maggie Sergio reported last year at Huffington Post, netting attached to the two Petaluma viaducts by Caltrans contractor C.C. Myers ended up entangling more than a dozen cliff swallows, barn swallows, and other birds every day during April 2013. As Sergio wrote, C.C. Myers' crews would remove and discard the dead birds every day and then reattach the netting, which would then -- as shown in this photo by George Eade -- kill yet more birds. Given that the intent of attaching the netting in the first place was apparently to protect swallows by keeping them from building nests in a construction site, the agency's seeming intransigence over making changes to the netting setup angered many conservationists.

Native Songbird Care and Conservation was joined in its May 2013 lawsuit by the Center for Biological Diversity and the Golden Gate, Madrone, and Marin Audubon Societies. According to a Center for Biological Diversity press release, the Federal Highway Administration, which is funding the Petaluma River and Lakeville Road bridge projects, is also expected to sign the agreement.

As part of the settlement, Caltrans has agreed to use other means to exclude nesting birds from its construction and demolition projects in Petaluma and elsewhere, including using rigid barriers that don't pose a risk of entanglement. The agency may also hire biologists to remove started nests from project sites before eggs have been laid, or reschedule projects to avoid nesting season entirely.

"We're pleased that Caltrans is removing the ineffective and deadly netting from these important swallow nesting locations, and will use safer measures to keep swallows from nesting in construction zones," said Veronica Bowers of Native Songbird Care and Conservation. "It's important that Caltrans continue to meet with wildlife agencies, conservation groups and our swallow expert before each nesting season during the project to assess the effectiveness of bird exclusion measures at the bridges."