Pocket gophers (Thomomys bottae), voles (Microtus californicus), and mice (Mus musculus, Peromyscus spp.) incur major costs to agriculture in California and worldwide. Introducing natural predators, such as American barn owls (Tyto furcata), shows promise as a solution to help manage rodent pests in a variety of crop systems, including winegrape vineyards. However, little work has evaluated the cost and efficacy of this pest removal service. To fill this gap, we simulate the cost and efficacy of using barn owl nest boxes and compare it to estimates for that of lethal trapping in California’s winegrape vineyards. We found that it is cheaper to install barn owl boxes ($5.50 - $26.67 per acre per year) than to trap rodent pests ($72.57 - $227.52 per acre per year for gophers, and $237.57 - $552.67 per acre per year for voles and mice). However, the efficacy of using barn owls was only comparable to trapping if rodent densities were low, and even when nest boxes were deployed at their highest modeled density (1 per 5 acre), owl nest boxes could not achieve as high an efficacy as rodent trapping if intermediate and high rodent densities were present. Growers can use our assessments of efficacy for comparative purposes across treatment strategies, but because models in this study did not account for rodent reproduction nor immigration, growers should not directly relate costs to efficacies. For effective integrated pest management (IPM), we recommend that growers decrease rodent densities with targeted trapping and habitat modification, then use barn owls to help maintain lower rodent densities in most years, coupled with more intensive trapping when rodent numbers periodically spike.