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These Grapes Are NOT for the Birds

August 17, 1995|DAN BERGER

Harvest time is approaching in West Coast vineyards; in some areas, grapes for sparkling wine have already been picked. It's the time of year when growers turn their eyes anxiously toward the skies, searching with concern.

But it's not rain they fear most; it is something more dreadful, a scourge that could destroy the best of vineyards and cost a farmer an entire year's harvest: Birds.

Massive flocks of grape-eating birds are among the most aggressive enemies of vines. Birds typically begin pecking at grapes when the fruit reaches about 15% of sugar. Wine can't be made from such underripe grapes; growers usually wait until at least 21% sugar before harvesting.

This gives as much as a three-week head start to the birds.

Birds that can cause vine damage are abundant on the West Coast. The most prevalent is the European starling, a noisy bird with odious habits, including the usurping of other birds' nests. They eat grapes and peck holes in those they don't eat.

"Left to their own devices, they could destroy a crop," says David Graves, co-owner and winemaker at Saintsbury Vineyards in the Carneros district of Napa Valley.

The starling, which migrates north to cooler weather during summer, returns to Napa and Sonoma just about the time the later-harvested grape varieties are ripening.

It's not possible to completely control the millions of starlings and other birds--like finches and robins--that are pests in vineyards. The best a farmer can do is limit the damage. Here are a few of the steps your favorite grape grower may take this harvest:

* Netting. Many ring their vineyards with netting to keep the birds away. One form of net is strung on poles and works fine, except that some birds eager for the fruit get caught in the nets and then must be freed. Harvesting fruit under netting is, alas, slow and costly.

* Scare tactics. Some vineyard people use the equivalent of scarecrows or other frightening mechanisms, like aluminum strips that reflect sunlight. One popular trick is to erect plastic barn owls on posts or roofs. The barn owl is a natural predator of the starling; if a starling sees a barn owl or an owl look-alike, it makes a fast exit.

* Explosives. Some wineries use propane-powered canons, or what Graves calls "the old reliable 12-gauge shotgun." They don't shoot anything, but every few minutes there is a loud boom. The birds think they are being shot at. Result: retreat.

Of late, a new and natural solution has been found that seems to work better.

Saintsbury, Frog's Leap Winery and Shafer Vineyards are among the wineries trying to solve bird and other pest problems by building nests for bird species that are natural predators of the grape-eating birds.

Since about 1990, when efforts began, results have been very rewarding. For instance, Graves says, Saintsbury is building and erecting nesting boxes for the kestrel, a tiny hawk formerly called a sparrow hawk.

"They're pretty common," says Graves. "They are generalists and they're carnivores, so they could eat a finch. Also, they don't like starlings, who try to take over their nests."

When kestrel nests are erected in vineyards, starlings quickly learn it's not a good idea to be a home-wrecker. "It's kind of like a sharp stick in the eye," Graves says of the kestrel attack. "Pretty soon, the starlings don't stick around."

Graves also has erected perches in his vineyards to make the job of a Swainson's hawk easier. "The Swainson is related to the red-tail hawk," he says. "They eat rodents, so they keep down the vole and gopher population."

He points out that raptors like falcons and barn owls that eat birds "take well to living in human-built structures, and they are very good predators, with very good hearing and vision, so they attack rats and mice too."

Saintsbury also has erected more than 60 boxes specifically designed to attract bluebirds, which Graves says forage for insects in the canopy of the vine, keeping down the insect population.

The bird campaign is being conducted as part of the Audubon Society's program called Keeping Common Birds Common. It is also part of the efforts of some wineries attempting to grow grapes organically, because birds do some of the jobs that pesticides do.

Frog's Leap's owner-winemaker, John Williams, is a major believer in attracting beneficent birds and one of the state's strongest advocates of the organic growing of grapes. In such an environment, he says, without the help of chemical aids to fight off pests, the vine is not given an easy life. The vine must become stronger and fight off its enemies more vigorously.

"That means you have to train your vines to accept a different system," says Williams.

Instead of chemical fertilizers and pesticides, vines are given protection of a different sort--an infusion of beneficial creatures, like ladybugs, that reduce the bad creature population.

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