Illegal drone at California wetland forces birds to abandon nests, leaving 3000 eggs behind

Tern eggs were abandoned at the Bolsa Chica Ecological Reserve after being scared off by drones. Photo / AP

Around 3000 elegant tern eggs were abandoned at a Southern California nesting island after a drone crashed and scared off the birds.

Two drones were flown illegally over the Bolsa Chica Ecological Reserve in Huntington Beach in May and one of them went down in the wetlands, the Orange County Register said.

Fearing an attack from a predator, several thousand terns abandoned their ground nests, according to the state Department of Fish and Wildlife.

Now, during the month when the white birds would be overseeing their eggs as they begin to hatch, the sand is littered with egg shells.

It's one of the largest-scale abandonment of eggs ever at the coastal site about 160km north of San Diego, according to reserve manager Melissa Loebl.

With the pandemic driving more and more people to outdoor spaces, last year saw about 100,000 visitors to the Bolsa Chica reserve – up from about 60,000 the previous year, Loebl said told the newspaper.

That's contributed not only to increased drone activity, but also to more dogs and bicycles on the trails – all of which are prohibited.

"We've seen a significant increase in dogs, particularly off-leash," Loebl said. "That's devastating for wildlife and this is prime nesting season. The dogs chase the birds and the birds abandon their nests."

Another problem is the development of multimillion-dollar homes on the hillside at the north end of the reserve overlooking the wetlands, said Fish and Wildlife warden Nick Molsberry. While most residents respect the sensitive nature of the estuary, there are a few scofflaws, he said.

"It's residents that sometimes feel entitled, that feel they should be able to use the land as they like," Molsberry said. Authorities are ramping up enforcement and citing people who break the rules.

At nearly 607ha, the reserve is the largest saltwater marsh between Monterey Bay just south of San Francisco and the Tijuana River Estuary in Mexico. Some 800 species of plants and animals live at or migrate to Bolsa Chica.