Caltrans officials said Tuesday that a contractor has fixed a problem with netting being improperly installed under Highway 101 bridges in Petaluma, which was resulting in dozens of migratory birds getting trapped and dying. Wildlife advocates, however, remained skeptical, saying they had found dead swallows in the netting as late as Wednesday, and continued to call for the netting's removal.

The issue first came to the public's attention on April 11, when local wildlife advocates, led by Veronica Bowers of the songbird rescue organization Native Songbird Care & Conservation, reported that dozens of birds were flying through gaps in the netting, getting stuck inside it, and slowly dying.

The birds were cliff swallows, small black and white songbirds with ruby throats that migrate to Sonoma County from South America in order to reproduce. They have traditionally built their mud nests under the bridges that cross over Lakeville Highway and the Petaluma River.

The netting was applied under those bridges by CC Myers, Inc., a company contracting with Caltrans, in an effort to keep the birds from building nests there as construction gets underway on a $77 million project. That project will, among other things, widen the bridge over Lakeville Highway and replace the Petaluma River Bridge spans and is paving the way for the eventual widening of Highway 101 through Petaluma.

Caltrans officials said the agency is required to exclude the birds from the construction area by state and federal regulations, including the Migratory Bird Treaty Act.

But bird advocates said last week that the nets were sloppily applied and doing more harm than good.

They counted dozens of birds that had been killed since April 7, questioned the contractor's sluggish response, and asked that the nets be taken down immediately. They suggested replacing them with an alternative exclusion method, such as silicon paint or teflon sheeting, which would also prevent the birds from nesting under the bridge.

Caltrans spokesman Bob Haus said last week that Caltrans had been in close communication with the U.S. Fish and Wildlife Service and the California Department of Fish and Wildlife after discovering the problem on March 27, and that the contractor planned to have fixed the issue by Sunday. The reason it took so long, Haus said, is the netting's location under a bridge.

"Access is difficult, lanes have to be closed at night," he said at the time.

On Tuesday, Haus confirmed that the contractor had worked over the weekend to tighten the nets and eliminate gaps. He added that biologists employed by his agency found the efforts appeared to be keeping swallows out of the netting, and that the biologists are continuing to inspect the netting to make sure the swallows are no longer getting entangled.

"We don't want another bird to die," said another spokesperson, Tamie McGowen. "That's why we have the nets up in the first place."

The U.S. Fish and Wildlife Service, which apparently has taken the lead in investigating the matter, would not comment on the investigation since it is ongoing.

A spokesperson for the California Department of Fish and Wildlife, Janice Mackey, said on Tuesday that her agency was in touch with Caltrans and had been told that, as of Monday, the nets were working and that no new dead birds had been found.

Bowers, however, continued to question the netting, contesting that there was "once-living proof that the netting is not working." She acknowledged that the number of dead and trapped birds was dwindling but said that dead swallows had still been found in the netting as late as Wednesday this week.

Shes has been counting the number of trapped birds each night, being careful not to count the same bird twice. Between Sunday April 7 and last Sunday, she counted 82 dead birds.

She added that other swallows are building nests on the wood holding the netting in place.

"It hasn't achieved what they said it would achieve, which is excluding the swallows from the area," she said.

Bowers and other local bird advocates have started a petition asking Caltrans to take down the netting that had gathered about 800 signatures by Wednesday night.

(Contact Jamie Hansen at jamie.hansen@arguscourier.com.)