Certified organic farms must promote biodiversity, which in turn provides important services for the farm and improves crop yields. A recent study published in the journal Ecological applications found that the benefits of biodiversity such as birds on organic farms increase when there are many natural habitats that surround the farm.
The presence of birds on farms can create tension. While birds are often useful and provide natural pest control, they can themselves be pests when they eat the crop, and some fear that birds are carriers of foodborne pathogens. This study quantified the net benefits of birds on organic strawberry fields, taking into account their contributions to natural pest control, the damage they cause from plant consumption, and the risk to food safety from faecal contamination in the fields. They found that the pros and cons of birds largely depended on the amount of near-natural habitat around the farm. When there is more habitat in the landscape, the net benefit to birds increases. It is important to note that while birds eat up to 3.6% less strawberries, this is very small compared to damage caused by the most dominant insect pest (Lygus hesperus), which caused more than 30% less yield was what points to the importance of any pest control that birds could offer.
The farmers in this study expressed a deep commitment to providing safe food to consumers. Since strawberries are harvested by hand, contaminated berries are identified and sorted out. Despite farmers' concerns about birds that transmit foodborne pathogens, the study found that with only 0.01%, contamination of berries with faeces was extremely rare. The contamination was not affected by the vegetation on and around the farm, but by the number of fences on the farm. More fences allowed more bird squatting and thus more contamination. Overall, this study shows that preserving a natural habitat on farms can increase the net benefits for birds without increasing the risks to food safety.