House sparrow damage to peppers in greenhouses can be decreased by reducing access

Greenhouses are one of the most intensified agricultural production systems and where the impact of insect pests has been studied the most, yet there is little information on bird pests affecting crops grown under plastic. To uncover potential conflicts between birds and farmers in southeast Spain, where the highest concentration of greenhouses in Global North is found, we surveyed local farmers to obtain information about the bird species most affecting their crops, the most common methods used to deter them and the crops most impacted by birds. Farmers identified the house sparrow (Passer domesticus) as the species that most affected their crops, especially pepper. Sealing the greenhouse and the use of (illegal) mist nets were the most common methods displayed to deter birds. We also assessed bird damage to pepper (Capsicum annuum, L. cv. Palermo) crops in 21 greenhouses and estimated the economic losses for farmers. Of the eleven species detected inside greenhouses, the house sparrow caused by far the most damage to pepper crops. Our estimates in sampled greenhouses predict economic losses of 1406.8 €/ha per annual pepper crop due to bird damage. Sealing greenhouses effectively prevented birds from entering greenhouses, in contrast to illegal mist netting. Finally, we revealed for the first time the widespread and illegal use of cats outside greenhouses to try to reduce bird populations. This would have negative consequences for the native wildlife living in and around greenhouses. Our findings underscore the need to invest more resources in control mechanisms that ensure the development of sustainable farming practices with bird communities.