With its bright blue back and rust-colored chest, it’s easy to see why the western bluebird is a frequent birder’s favorite. Soon viticulturists may number among its fans as well.
According to the research Dr. Julie Jedlicka conducted as part of her doctoral thesis at UC–Santa Cruz, the western bluebird may serve as a natural alternative to insecticides to manage some of the pests that invade California’s vineyards. Jedlicka found that placing nesting boxes on vineyard plots lures in populations of the entirely insectivorous bird, which in turn can fend off insect-borne blights such as the deadly Pierce’s disease.
After placing pieces of what she calls “highly energetic yummy pieces of bluebird food” on plots both with and without nesting boxes, Jedlicka found that 2.4 times more insects vanished (presumably because they were eaten) from the plots containing nesting boxes, probably due to the fact that sites containing nesting boxes saw a tenfold increase in bluebirds sightings.
Ron Rosenbrand, vineyard manager of Napa Valley’s Spring Mountain Vineyard, has put this research into practice. He says he discovered the agricultural value of the western bluebird while trying to figure out a way to manage his infestation of blue-green sharpshooters, an insect that spreads the dreaded Pierce’s disease. When told he could attract bluebirds by providing homes for them, he took at building bluebird-sized nesting boxes with a vengeance. Five years and 800 boxes later, Rosenbrand says he now rarely finds blue-green sharpshooters in his fields and has “almost zero cases of Pierce’s disease.”
Of the bluebird, Rosenbrand says, “Not only are they beautiful to look at, they’re tremendously effective. It’s great having Mother Nature actually work with you rather than against you as a farmer.”
Although her research is just out, Jedlicka explains that the thought of using birds for pest control is not necessarily novel. “They used to do studies on whether birds were effective natural predators on pest populations back in the 1950s, before pesticides were on the market,” she says.
Since the 1950s, much of the bluebird’s preferred habitats—oak woodlands and savannas—have been converted into agricultural and urban land. The fact that the bluebird’s propensity to eat squirmy grub has earned it a new home in some California vineyards offers a hopeful solution to the species decline it has experienced over the 20th century. Jedlicka says that, ultimately, she is “looking at how we can bring birds back into the system in a way that can lower pest populations and create win-win scenarios.”
Originally published in the Santa Cruz Weekly: