Pistachio growers, focused on preventing crop losses due to crows and ravens, have employed various noisemaking and scaring devices and have even paid shooters to keep crows out of their orchards.

Drones may become the next tool used by pistachio growers to protect their crop from crows and ravens. Crows are the main culprit in pistachio orchards, feeding in large numbers and moving from orchard to orchard.

Page Klug, a USDA research wildlife biologist and project leader at the North Dakota Field Station, isn’t working with pistachio-craving crows, but she is conducting research on keeping mixed flocks of blackbirds out of North Dakota sunflower fields with drones.

She is conducting hazing trials and finding birds learn how long the drones are in the air and know how long they have to hunker down under the tree canopy before the drone leaves. Bird response to drones also includes chasing them. Different bird species react differently, Klug said.

She said birds can learn to avoid drones operated on a set path as they do other deterrents, so the direct approach of hazing birds with drones is not being considered. Instead, technology, including, automation and image processing combined with the drone, may improve their efficacy.

Sending drones in varied patterns over an orchard or field is necessary, eliminating labor costs. But, Klug said that they must also be able to distinguish pest or target birds to keep them from settling in orchard and damaging crops. Image processing would allow the drone to target certain bird species.

Klug noted that monitoring early in the growing season will give growers an idea of the pest bird pressure. It is important to prevent crows from becoming habituated to an orchard site as that will make it harder to frighten them away. Klug said the pest birds will have to have an alternative site.

Bird damage usually is most severe in areas where birds find refuge, breeding sites and other sources of food. Habitat modification can help move birds out of an orchard. Eliminating roosting trees along orchard perimeters is recommended.

California Fish and Wildlife regulations allow crows to be taken only by landowners or tenants, or by persons authorized in writing by such landowners or tenants when crows are committing or about to commit depredations (damage to crops).