San Francisco --

A nesting pair of California clapper rails and their two chicks have been confirmed in San Francisco's Heron's Head Park, the first time in decades that the endangered chicken-like bird has been documented breeding in the city.

The discovery has Bay Area birders in a flutter, particularly considering the location of the feathered family. The shy, marsh-loving waterfowl were nesting in a restored wetland near Hunters Point, an area not normally associated with a well-functioning ecosystem.

"It's not pristine habitat and there are a lot of predators around, so this may not be the perfect situation, but it shows that if you create habitat for these creatures, they will move in and breed," said Alan Hopkins, the past president of the Golden Gate Audubon Society and an organizer of the annual San Francisco bird count. "This is a success story."

The federally listed endangered species has been under a U.S. Fish and Wildlife Service recovery plan since 1984. It was thought to be pretty much extinct in San Francisco until last year when a single clapper rail was spotted in the park. Birders weren't impressed, though. It seemed to them an isolated adventure by a transient bird.

Then, on Aug. 8, birder Dominik Mosur trained his binoculars on the pickleweed next to a slough at Heron's Head.

"I spotted these two clapper rail chicks running across the slough," said Mosur, 34, who spends virtually all his spare time watching fowl. "They were running from one area of cover to the other."

Mosur managed to snap some photographs of the birds before he went bonkers, shouting for joy and then rushing home to document his find.

"It was mind blowing. I was overjoyed and calling everybody I know," he said. "It was like running into your favorite rock star in a cafe and they are willing to talk to you. I was giddy for days. I'm still giddy."

Experts concluded that the chicks were 6 weeks old when they were first spotted, meaning they must have been born in the park.

Habitat disappears

Hundreds of thousands of clapper rails once waddled through the wetlands from Monterey to Humboldt County, including San Francisco, where they thrived. Before it was developed, the city by the bay was surrounded by marshlands that provided habitat for the squat, clumsy birds.

But the creatures were no match for the hungry hordes who began pouring into San Francisco some 160 years ago. Clapper rails don't swim or fly very well, and spend most of their time hiding or scampering awkwardly between bunches of tall grass.

It turned out that they taste pretty good, too - kind of like chicken. Their numbers were decimated until 1915, when commercial hunting of the bird was banned.

Then another problem arose. The filling of the wetlands and marshes around the Bay Area over the past century depleted their habitat by 90 percent. The unfortunate release and subsequent population explosion of nonnative red foxes nearly killed the birds off completely.

By 1971, the number of clapper rails in California had dropped to 500 or so, and the plump, sedentary bird made the federal and state endangered species lists. Wetlands restoration over the past few decades has helped bring back the clapper rail population to between 1,000 and 1,500, according to wildlife biologists.

One of the restoration projects that apparently made a difference was on a 24-acre site on San Francisco's southern waterfront once known as Pier 98. The bay had been filled by the Port of San Francisco in the early 1970s in preparation for the construction of a cargo ship terminal.

The terminal was never built and the ugly, debris-strewn area remained a blight on the landscape for decades. But then nature intervened. Pickleweed grew and the tides began to form a salt marsh that attracted waterfowl, and eventually bird watchers, who pushed for the creation of a park.

Wetland restoration

In the late 1990s, the port, the San Francisco Public Utilities Commission, California Coastal Conservancy and the San Francisco Bay Trail Project came up with $1.8 million to restore the area as a wetland and park. In 1999, it reopened to the public as Heron's Head Park, named for its resemblance - when viewed from the air - to one of its regulars, the great blue heron.

Still, clapper rails were never expected to begin breeding and nesting there.

"Nobody alive today remembers ever seeing nesting clapper rails in San Francisco," said Hopkins, one of the foremost experts on waterfowl in the city. "They nested along the bay shore in San Mateo County about 15 miles away, but there was no habitat in San Francisco."

Fish and Wildlife officials are urging people to avoid the park wetlands so as not to disturb the chicks, at least until they are able to fly, which is expected to be around the first week of September.

"The port invested a lot in the restoration of Heron's Head Park, so we are really excited about this," said Carol Bach, the environmental and regulatory affairs officer for the port. "We've had several years of successful nesting by American avocets, and then this year, with the successful nesting of the California clapper rail, that takes it to a whole new level because now it is endangered species habitat."