Bird management options for fruit growers
Bird damage may be more intense in dry years as birds turn to fruit to meet their nutrition and hydration needs. Fruit growers can employ one or more bird deterrent strategies.
Many birds eat fruit to help meet their water requirements in addition to their energy requirements. In dry years like 2016, when other water sources are limited, birds many depend on fruit to a greater extent than usual. A number of growers are reporting high bird activity in their fruit.
The quickest bird deterrents to deploy are auditory and visual scare devices, like units than play bird distress calls and inflatable tube men. Birds habituate to many deterrents quickly, however, so the devices are more likely to be effective if they go on and off randomly, are moved frequently and are used in concert. For example, a recent study showed that the deterrent effect of combined auditory and visual deterrents lasted more days for ring-billed gulls, which are known to eat fruit, compared to when a visual or auditory device was deployed on its own.
Keeping track of “hot spots” for bird activity on your farm and targeting those spots with sustained and vigorous deterrent effort may help. Harvesting ripe fruit in a timely manner will reduce the availability of the fruit to birds and may reduce losses. Light deterrents, like lasers, deter some bird species. However, keep in mind that evidence for their effectiveness has come primarily in low-light situations, like at dusk or at night.
Bird management strategies that take more lead time and investment include physical barriers like netting that can be employed in short-stature crops. Ideally, netting should be on a frame so it does not lie on the fruit and be anchored to the ground. Otherwise birds can still access the fruit.
Over the long term, growers should think about habitat management. Our previous work has shown that in some contexts where there is less fruit, like edges of fruit blocks adjacent to non-fruit, percent bird damage can be higher. Arranging blocks to minimize non-fruit edges could lower the amount of the crop at risk for bird damage. Growers can also consider improving habitat for species that may deter pest birds. We have found remains of fruit-eating birds in nest boxes we installed for American kestrels, which are small predatory birds, in cherry orchards and blueberry fields. As an added benefit, kestrels eat voles and pest insects.
In very high-damage contexts, growers can consider applying for a permit for lethal control of birds. However, the permit application process may take a number of weeks. For more information, see “Do I need a permit to control wildlife on my farm?” by Michigan State University Extension.
The Federal Aviation Administration has new rules regarding Unmanned Aircraft Systems (drones) that will take effect in August 2016. Once drone technology is a bit less dependent on human direction, it may be useful in deterring birds.
Each farm is unique and should be assessed for potential risk factors. See pages 211-218, Sample Bird Management Plan, of “Managing Bird Damage to Fruit and Other Horticultural Crops” for more information.
For information about deploying kestrel nest boxes, please email me, Catherine Lindell, at email@example.com.