The El Segundo blue butterfly is back.

Once relegated to a few small and fragile reserves, the nearly extinct butterfly with electric blue wings has expanded its territory to take up residence along the bluffs of Redondo Beach, said USC research assistant professor Travis Longcore.

A few hundred are now living and breeding in the four-acre area where tourists, surfers and beachcombers can get a close look at the rare species.

“In the national picture, this project is yet more evidence that the Endangered Species Act works, and that species recovery is not only possible, but sometimes even involves a walk on the beach,” said Longcore, who also is the science director for the Urban Wildlands Group.

Until last month, the species only existed in three special reserves set away from the crowds.

“This is an important step in breaking down the barriers between people and nature in the city,” Longcore said.

Less than 1 inch across, the butterflies journeyed from their protected environment to the beach because the invasive ice plant had been removed and replaced with native vegetation – namely dune buckwheat – that not only provides the butterfly with nectar but also with a place to lay its delicate eggs.

The butterfly, whose wings sport gray and black spots on one side and an azure blue on the other, was first placed on the Endangered Species list in 1976.

Longcore never imagined the tiny butterflies would make the trip to the bluffs and buckwheat on their own.

“Although the colonization was a surprise – experts thought the butterflies would need to be introduced by hand – it was not an accident,” Longcore said. “This project is an example of cooperative conservation, where goals are met through carefully crafted consensus and voluntary action.“

Four years ago, Longcore and Redondo Beach resident Ann Dalkey formed the Beach Bluffs Restoration Project to spearhead the restoration along Santa Monica Bay. The Santa Monica Bay Restoration Commission, the Urban Wildlands Group and the Los Angeles Conservation Corps’ Science, Education and Adventure Lab program all supported the effort.

Using at-risk youth and volunteers, the groups pulled out the ice plant and put in buckwheat, California sunflower, deer weed, lupines, prickly pear cactus, ambrosia and sand verbena.

The project was funded by the Coastal Conservancy, the City of Redondo Beach and the Los Angeles County Department of Beaches and Harbors.