Bugs, Birds, Bats and Beyond

Sustainable Farming at Shafer Vineyards and other California Wineries

Twenty years ago a Napa Valley vineyard was supposed to look as clean as a pool table: not a blade of grass, not a weed, no sign of bird or insect life, just knobby vines sticking up out of the soil. The only way to achieve that stripped-down look was by tainting the soil with rodent poison to kill moles and gophers, by spraying potent herbicides to kill unwanted foliage, and by applying some powerful insecticides to vanquish the bug world. Not only was it costly, it wasn’t a sustainable way to farm. Today, we are partnering with owls, songbirds, hawks, bats and other wildlife to cultivate our vineyards. Thanks to their efforts, along with cover crops, we don’t use insecticides, chemical fertilizers or rodent poisons.

A Feathery Trend

Shafer is one of a handful of Napa Valley wineries that are evolving the way we farm (Shafer was named one of the “World’s 25 Great Vineyards” in 2002 by Wine & Spirits magazine).

Other names are Frog's Leap, Honig Vineyard & Winery, Saintsbury, Harlan Estate, Robert Sinskey Vineyards and more. Ann Smith, a member and past president of the local chapter of the Audubon Society, who has visited numerous Napa Valley wineries, says that the use of songbirds, owls and bats as part of sustainable farming is “seriously on the rise.” She adds, “This was unheard of 15 years ago.” Robert Zlomke, District Manager, Napa County Resource Conservation District says he is seeing a marked trend in Napa Valley wineries turning to “the wild kingdom” for help in growing some of the world’s most celebrated wine grapes.

Owls and Hawks at Work

At Shafer we started our sustainable farming efforts in two ways back in the late 1980s. First we erected nesting boxes for owls. The owls had to discover the boxes; we didn’t capture them and place them inside. But we had no problem attracting them and within a couple of years we saw 100 percent occupancy. Within a year or so of starting the owl program, we erected perch poles, which attract raptors such as Red shouldered Hawks, Red tailed Hawks, and American Kestrels. The reason we want to attract owls and hawks is simple – we wanted to stop putting rodent poisons in the soil to halt the spread of gophers and moles. Gophers and moles like to tunnel through the ground and eat young vine roots. Between the hawks and owls, we have day and night rodent patrol (hawks feed during the day, while owls are nocturnal hunters).

Today thanks to the hawks and owls, our rodent population is under control and no more rodent poisons are in our soil. The work of these raptors is so effective we named our Chardonnay vineyard “Red Shoulder Ranch” to honor them.

Of Bats and Birds

But gophers are only one of a vineyard's many pests. A greater number are insects such as blue-green sharpshooters and leafhoppers. We are working to replicate the night-and-day patrol idea, again using flying hunters. To this end we’ve erected a 500-lb bat roost, which is currently awaiting its first residents (just as we had to wait for the first owls over a decade ago). The box rests on two 20 ft poles and towers over one end of our hillside vineyards. The box was designed and built by our wildlife consultant, Greg Tartarian of Wildlife Research Associates in Petaluma, California. He also designed and built our first owl boxes. The bat box is designed to hold 400 to 1,000 bats (depending on the mix of species) and it will be a maternity colony, meaning this is a place where the bats will breed and raise their young.

Bats are big eaters – consuming anywhere from 15 to 25 percent of their body weight per night as they cruise through the moonlight. Given our location at the base of towering cliffs, called palisades, we already enjoy some insect patrolling by bats. This new roost is designed to attract even more to put a permanent dent in the number of bugs that chomp our vines. For daytime insect feeding, we have erected songbird houses throughout our vineyards. These provide homes for cavity-dwelling species such as swallows and bluebirds, who tend to eat the flying bugs that blight our vines.

Cover crops

Another key part of farming sustainably is the use of cover crops. Remember that pool-table look that our vineyards once had? Today they grow wild and wooly with clover, vetch, oats and other vegetation that creates a lively habitat where “good bugs” eat “bad bugs.” More specifically, insects such as spiders and ladybugs naturally prey on vine-blighting insects such as leafhoppers and blue-green sharpshooters. Cover crops do double and triple duty. They control erosion. They choke back weeds we don’t want. They control the vigor of the vine. They enrich our soils with nitrogen and other important nutrients at the end of their lifecycle and more.

Shafer Vineyards Harvests the Sun - utilizing solar energy to power production.