Gulls reap benefits of ballgames 

If Brian Wilson is called to the mound this afternoon, he can expect some feathery company.

Western gulls, most of which nest at Alcatraz Island, have a remarkable knack for showing up at the nearby AT&T Park for the final outs of the ninth inning.

The intelligent, 2-foot birds are scavengers that will eat just about anything.

During the baseball season in the South Beach neighborhood, that includes bounties of garlic fries, half-eaten hot dogs and other ballpark leftovers.

The overhead flock of white-and-gray birds swells rapidly as a game draws to a close, regardless of whether it’s played in the afternoon or evening, according to Jorge Costa, a ballpark operations manager with 21 years of experience working for the Giants.

“They materialize for the games,” Costa said. “They just kind of have this innate sense; the only thing that throws them off sometimes is daylight savings.”

The birds, however, create problems, Costa said. They dump trash on fans, rush into the seats for food before a game is finished and can get in the way of players and baseballs.

While pigeons can be kept out of areas using nets, little can be done about the heftier gulls.

The hungry flock has been growing in the 10 years since the waterfront ballpark opened and the Giants relocated from Candlestick Park, Costa said.

“In the last couple of years, it just seems like there’s more of them,” he said.

Golden Gate Audubon volunteer leader Dan Murphy said bright lights, such as those used at AT&T Park, can attract gulls.

But the gulls’ uncanny ability to time their trip to AT&T Park as a game is drawing to a close is the likely result of a wide range of other visual clues, he said.

Gulls rely heavily on sight and are probably conditioned to recognize a growing stream of disappearing fans.

“As those seats clear out, they just know from experience that there is food,” Murphy said. “Once one of them finds it, they will congregate.”

About 80 percent of the Bay Area’s Western gulls nest on Alcatraz Island, with most of the others nesting along the mainland’s waterfront, Murphy said.

They are currently incubating eggs or caring for chicks, and Murphy said their numbers at the ballpark could swell after midsummer, when both parents are freed from rearing duties to search for food.

For the birds

Western gulls can be seen all over the Bay Area.

200 Gull colonies in Northwestern America

80 percent Bay Area nests found on Alcatraz Island

3 Average eggs per nest

7 weeks Age when the birds can fly

10 weeks Age when they leave the nest

4 years Age when full maturity is reached

21 inches Average length at maturity

55 inches Average wingspan

Source: Audubon Society, U.S. Geological Survey

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