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Bird population declines

The height of summer beach season at Bolsa Chica State Beach is also the height of nesting season at Bolsa Chica Ecological Reserve. As you’re probably aware, California least terns and Western snowy plovers like to nest on sandy beaches. But during the first part of the 20th century, their habitats were taken over by people with our parking lots and beach blankets. The populations of our locally nesting terns and plovers plummeted.

The Bolsa Chica Ecological Reserve was created in the early 1970s in large part to protect the endangered California least tern. Inner Bolsa Bay was re-opened to tidal flushing, creating habitat for the fish that terns feed on. And to give the birds somewhere to nest and raise their young, two sand islands were created in the bay mimicking the sandy beaches that they used to use.


In ensuing decades, birds flocked to the new nesting islands, and each year, the number of birds using them grew. Other species of terns never before observed breeding in this area came to Bolsa Chica to nest. The tide had been turned.

In August 2006 another large section of Bolsa Chica was reopened to tidal flushing for the first time in over a century. A nesting area the size of a small airport landing strip was established behind a chain-link fence at the end of the boardwalk at the south parking lot. Again, the birds flocked to it.


Part of the newly opened wetlands was planted with cordgrass and eelgrass. One of the goals was to attract nesting light-footed clapper rails, a highly endangered species that nests at Upper Newport Bay and the Seal Beach National Wildlife Refuge. These secretive birds can be seen on occasion near the boardwalk, but they haven’t nested here for as far back as anyone can remember.

Vic talked last week with Dick Zembal, formerly of the U.S. Fish and Wildlife Service, and probably the foremost expert on the light-footed clapper rail. Zembal and some volunteers (me included) had built some clapper rail nesting platforms and put them in Inner Bolsa Bay in the early 1990s. But they were never used and were eventually removed.

This spring, Zembal heard the mating calls of a pair of clapper rails at Bolsa Chica, about 150 yards north of the south parking lot. When Vic heard about it, he was thrilled. We were one step closer to getting nesting rails back.

Unfortunately, there have been no further reports of rail nesting behavior at Bolsa Chica this year. Neither Zembal nor either of the Department of Fish and Game biologists at Bolsa, Kelly O’Reilly or Peter Knapp, have seen any evidence of successful breeding.


The rails still face numerous obstacles to successfully re-colonizing Bolsa Chica. For one thing, when rails flush from the wetlands, they fly over land, not over water. When they are on the west side of the wetlands, that means that they flush toward the highway.

Indeed, a rail was found dead on Pacific Coast Highway this spring. It might have been one of the rails that Zembal heard calling. Or perhaps the pair was young and inexperienced, and this year’s nest failed. Either way, there appear to have been no nesting rails this year. But that could change any year now as the cordgrass matures and becomes denser.

O’Reilly told Vic that the nesting Western snowy plovers are doing well this year. But a coyote has caused some problems with the elegant terns and California least terns, preying upon some of the chicks. The coyote family living at Bolsa Chica had four pups this year, and they have to eat, too. It’s a dog-eat-dog world in the wild. Or a coyote-eat-bird world. Take your pick.

Coyotes and gulls have harassed the black skimmers as well, forcing these larger birds to move from their nesting area into the nesting areas of the least terns. The skimmers trampled the nests of the least terns, and the first attempt by the terns at nesting this season failed.


The least terns are now attempting a second nesting on the south tern island and a new spot for them near the Department of Fish and Game building on the east side of the full tidal basin. They have built 31 nests at that spot, dubbed Nest Site 2.

The terns and plovers are being more closely monitored now than in the past, thanks to a new volunteer program sponsored by the Bolsa Chica Conservancy. The program is modeled after the ones that provide volunteers for the tern colonies at Huntington State Beach and the Seal Beach National Wildlife Refuge.

At Bolsa Chica, volunteers sit at the end of the boardwalk, showing the nesting birds on the other side of the fence to passersby. The monitors also make regular reports about which predators are present, so Fish and Game can respond to protect the birds.

And if a watched nest is abandoned for a day, the volunteers can transport the eggs or chicks to the Wetlands and Wildlife Care Center for hand-rearing. This should result in a higher success rate of endangered bird nesting at Bolsa Chica.

There is still more good news about Bolsa Chica. The State Lands Commission has hired Sukut Construction Inc. to repair the eroded trails on the overlooks that were part of the full-tidal restoration project.

In the short time that the overlooks have been there, they have eroded so badly that O’Reilly could stand waist-deep in the furrows. The workers at Sukut have filled the gullies and covered the trails with red decomposed granite that will hopefully resist erosion better than the previous trail surface. Work should be finished on that project this week.

And here is a final piece of Bolsa Chica news. O’Reilly also said that work is now complete on the project to convert the gates for the muted tidal areas from manual to fully automated operation. This will provide a very high level of protection from any threat of oil spill or other contamination of the water.

The West gate is open, but the East and Middle gates won’t be opened until the end of Belding’s savannah sparrow nesting season. Bringing these new wetlands cells “online” will enhance the growth of pickleweed and provide higher-quality habitat for endangered Belding’s savannah sparrows next year. All in all, it’s been a very good summer so far at Bolsa Chica.