Bird services and disservices to strawberry farming in Californian agricultural landscapes.
Bird conservation in agricultural settings can be controversial. While some bird species damage some crops, others suppress insect pests. Few studies have simultaneously compared bird services and disservices to assess their net impact. Using an exclusion experiment in six California strawberry farms, we show that bird suppression of berry damage by insect pests (about 3.8% of berries) is similar in magnitude to the damage birds inflict on strawberries (about 3.2% of berries). Across 27 farms, we found that bird species richness and the relative abundance of insectivorous birds increased, while the relative abundance of strawberry-eating birds and bird damage decreased on farms with more semi-natural land cover in the surrounding landscapes (1000 m radius). Relative to homogeneous farms, those that implemented diversification practices, such as hedgerows, flower strips or increased crop diversity, had greater bird species richness, total relative abundance, insectivore abundance and strawberry-eating bird abundance. Synthesis and applications: Conserving semi-natural land cover in the surrounding landscape benefits bird species richness locally and aids farmers through reduced abundance of strawberry-eating birds and bird damage. These results highlight the need to consider both the services and disservices of birds when making management decisions.