Today, 80% of Napa Valley winemakers use owls to control their rodent population, while less than 20% use rodenticide instead.
Farmers realized that they only needed to build nest boxes near their fields to attract owls and reap the benefits. For example, a farmer with 20 owl boxes can expect those owls to catch around 70,000 rodents per year — which represents a cost of 26 cents per rodent, against several dollars for traditional methods (e.g. trapping, rodenticide).
Replacing pesticides with barn owls for rodent control is part of a broader environmentally sustainable trend among Napa Valley farmers. Indeed, many also reduce their water consumption in the face of Californian droughts and plant perennial grass between rows to prevent the dangers of monoculture.
Why does it matter? For decades, Napa Valley's wineries relied on pesticides to prevent rodents from damaging their crops. However, this strategy, coupled with grapes-only monoculture and the usage of commercial fertilizer, generated a toxic taint in certain wines, demonstrating the need for more sustainable practices. In January 2021, California passed a law restricting rodenticides, but lobbying created a loophole for agricultural use.
Although still technically authorized, Napa's growers turned away from rodenticides because they understood that people and nature depend on each other to thrive. Also, they took this opportunity to make a few raptor friends along the way.