Bird population declines

Natural Perspectives

July 07, 2010|By Vic Leipzig and Lou Murray
  • California least tern sitting on its nest in June, just across the fence at the end of the boardwalk.
California least tern sitting on its nest in June, just… (Photos by Lou Murray,…)

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.

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