During the day you can see a flutter of activity near the bridge as the swallows fly around looking for a good place to build their nests.
"The swallows have been nesting here for decades, literally," said Veronica Bowers, a Native Songbird Care & Conservation director in Sebastopol.
She noticed these nets under the bridge weeks ago. Caltrans spokesperson Bob Haus says it's to keep the birds from nesting there during construction, taking place nearby.
"If it's nesting season, you have to do anything you can to make sure the birds don't nest in the construction area. So it's for the protection of the birds," said Haus.
But over the last few weeks, the swallows have been getting in through gaps, getting tangled in the nets and dying. Bowers started seeing dead birds on Sunday and called those involved in the project on Monday.
"No one returned any calls. Tuesday it was the same thing, more dead birds, and then Wednesday of course the same thing, even more dead birds," said Bowers.
She says it is heartbreaking to watch and thinks the nets should be removed in favor of an alternate method. She said, "One of them involves Teflon sheeting, another one involves a silicone-based paint. Both of those are non-lethal methods."
Regardless, Haus says Caltrans has their solution.
"The plan is, number one, we are ordering a different type of net and we've been installing that. It is heavier duty and much more visible, but in the meantime, we are also closing the gaps," said Haus.
Caltrans expects to have all the nets fixed by Sunday. Until then, Bowers will be back out under the bridge to document all the dead birds.