Long-gone Swainson’s hawk returns to Bay Area

A Swainson’s hawk chick has hatched under the eye of Santa Clara County bird-watchers for the first time since the 1800s, suggesting that this elegant bird, a threatened species in California, may be on the road to recovery.

The nest location 16 miles south of downtown San Jose in the Coyote Creek Parkway is a well-kept secret among the region’s naturalists, thrilled by the sighting and fearful that crowds would prevent its parents from returning.

Its discovery proves the value of conservation in Coyote Valley, which faces major development pressures, according to bird lovers. “Ecstatic. Euphoric!” said De Anza College raptor biologist Ryan Phillips, describing his reaction to the sighting.

“This marks the return of the hawk to its historic range in the Santa Clara Valley and, even more important, shows how critically important and viable Coyote Valley is,” said Phillips, who monitored the nest. San Jose plans industrial and residential development in the north Coyote Valley.

Another beloved raptor, the bald eagle, is also making a Bay Area comeback, with a nest sighted this year in San Mateo County’s Crystal Springs Reservoir, for the first time in nearly a century, and several were reported in the East Bay.

The Swainson’s hawk is admired for its tenacious migration. It travels more than 6,000 miles each year from its winter home in Argentina. Most often seen in the Central Valley, its numbers are growing, Phillips said. In 1979, only 350 pairs existed in the state and the bird was listed as “threatened” under the California Endangered Species Act. Now there are 2,250 pairs in the state — a sixfold increase. Phillips credits their resurgence to state protection, pesticide bans and protected habitat.

“One pair of Swainson’s hawks is not a scientific study, but this species is showing a slow but steady expansion of its breeding range,” said Bob Power, director of the Santa Clara Valley Audubon Society.

Historical records show that the hawk nested sporadically in the county in the late 19th century, said Bill Bousman, a retired NASA research engineer who wrote the new 547-page tome “Breeding Bird Atlas of Santa Clara County.” In 1889, two eggs were collected on a swampy farm south of Gilroy and additional eggs were collected in 1894 in the Berryessa area, Bousman said.

“At that time, there were avid egg collectors. You could kill anything you wanted to, any time you wanted to,” he said. “In California, it was really wiped out and the population shifted to the east.”

Bousman routinely scans the trees along Coyote Creek for raptor nests and in the spring detected fresh green leaves in a nest atop an old sycamore.

“I sat down, kept my binoculars on and waited” until an adult Swainson’s hawk landed on the nest, Bousman said.

Dozens of walkers and bicyclists passed by while Bousman watched, only 300 yards from Highway 101.

The egg is believed to have been laid in mid-May, and the youngster was seen exercising its wings in the summer. For its safety, the discovery was disclosed only after the bird left its nest.

Now it may be winging its way to the warmth of South America. But the birds are known to reuse nests annually.

“The fact that we had a pair of nesting Swainson’s hawks in Coyote Valley is not only historic,” Power said, “but may — with a big emphasis on ‘may’ ” — show that an international campaign to protect these birds in Argentina is helping them breed successfully in California.

“There are too few good-news stories about birds and the environment,” he said.

Contact Lisa M. Krieger at 650-492-4098.