PS 23-59 - Barn owls (Tyto alba) and biodiversity near hemp farms and grasslands in Oregon, USA

Abstract: Extensive agriculture poses a major threat to biodiversity worldwide, although some species, such as the barn owl (Tyto alba), can thrive in many agroecosystems. Barn owls, the world's most widely distributed owl, provide rodent management, and their presence may be both an indicator of and support for ecosystem biodiversity. Little previous research documents the relationship between barn owls and adjacent crop attributes, however. In 2018, hemp (Cannabis sativa) was taken off the federal Controlled Substance Act list and permitted as an agricultural crop. Hemp is now rapidly increasing in extent in Oregon, USA. This research assessed the reproductive success and diet of barn owls, as well as the biodiversity of prey and nest visitors, near hemp fields as compared to near managed grasslands. I collected barn owl pellets and used camera data to assess nest success and prey diversity and to describe what other species visited nest boxes in five organic/no-spray hemp farms and six managed grasslands during the 2021 and 2022 nesting seasons. Barn owl nest box occupancy and success were similar, and vertebrate biodiversity was greater, in sites near hemp farms versus managed grasslands. Longer-term studies are needed to confirm my findings, but the observations indicate that hemp poses no greater threat and possibly more support to barn owl success and agroecosystem biodiversity than do managed grasslands.