California vineyards used owl boxes to attract barn owls, reducing rodent numbers by up to 52%

California vineyards installed over 500 barn owl nest boxes; fields with more owls had 38% to 52% fewer rodents.

Barn owls reduce rodent numbers by hunting and by making rodents more cautious, with fear increasing 16% to 38%.

The study was conducted by researchers Matt Johnson and Katherine Larson from Cal Poly Humboldt and Roger Baldwin from UC Davis.

The research took place in six vineyards in Napa Valley during 2023, and findings were published in Ecological Applications.

Using barn owls can help farmers reduce reliance on harmful pesticides while supporting biodiversity.