Habitat for endangered least tern restored at Carlsbad lagoon

Crushed oyster shells and curved roofing tiles are being spread this week to protect the nests of California least terns, a rare migratory bird that breeds in the sand near a railroad bridge under construction across the Batiquitos Lagoon in Carlsbad.

The California least tern is a white-and-black bird less than 10 inches long that breeds only in a few areas along the bays and lagoons of California and Mexico. Much of its coastal habitat has been lost to development, and as a result the bird is on the federal list of subspecies in danger of extinction.

The oyster shells and tiles will help camouflage the birds’ nests and protect the chicks and eggs from predators, the project managers said. The least tern typically lays its clutch of two or three eggs on the sand in the spring. When the chicks are grown, the birds fly south to spend the winter in Mexico.

“This is the fifth most productive least tern nesting site in the state,” said Gabriel Penaflor, reserve manager for the California Department of Fish and Wildlife.

Batiquitos Lagoon gets 400 to 600 least tern nests and produces 50 to 100 fledglings per year, Penaflor said. On Tuesday, workers were scattering the shells on a flat sandy area between the railroad tracks and Carlsbad Boulevard, also known as old Highway 101 or the Pacific Coast Highway.

The 4-acre site near the highway also was being reinforced with sand from the nearby bridge construction to repair erosion that occurred in ...