Birds can be a major nuisance for fruit farmers, as they feed on ripe fruit and damage crops. Farmers employ various techniques to keep birds away from their orchards and protect their harvest.
Why are birds a problem for fruit farmers?
Birds are naturally drawn to fruit as it ripens. The sweet, fleshy fruit provides an abundant source of food that birds readily seek out. Some of the most problematic bird species for fruit farmers include:
- Starlings
- Crows
- Pigeons
- Blackbirds
- Finches
These birds descend on orchards in large flocks and can decimate the fruit crop. Some birds will take one or two bites out of each fruit before moving onto the next. Other birds will gorge themselves, eating an entire fruit in one sitting. Both behaviors result in ruined, unsellable produce.
In addition to eating the fruit, birds also cause damage by:
- Pecking at and damaging the skin of the fruit, creating entry points for insects and disease
- Knocking fruit off trees before it is ripe
- Defecating on the fruit, introducing bacteria
- Disturbing buds and blossoms, inhibiting fruit development
Birds also compete with bees and other pollinators that fruit trees rely on. Their presence in orchards can significantly reduce crop yields.
When are birds most problematic?
Bird pressure on orchards intensifies as the fruit ripens. Different fruits ripen at different times of year:
- Spring fruits (apricots, cherries, plums): May – July
- Summer fruits (peaches, nectarines, figs): July – September
- Fall fruits (apples, pears, grapes): September – November
Migratory starlings, in particular, pose a major threat as they pass through regions during seasonal migrations.writeField(“Recurring seasonal bird threats:”);
- Spring fruits: starlings, blackbirds, crows
- Summer fruits: starlings, grackles, crows, finches
- Fall fruits: starlings, robins, crows, blackbirds
Birds will target ripening fruits at the edges of orchards first before moving deeper into the groves once the outer fruit has been eaten.
What damage can birds do to fruit crops?
Birds can have a significant economic impact on yields and profits for fruit farmers. Some key figures on bird damage include:
- Birds may eat up to 20% of certain fruit crops, such as cherries and grapes.
- Average annual loss of blueberries per acre due to birds ranges from $4,000-$11,000.
- Total annual bird damage to agriculture across the U.S. is estimated at $100 million.
Beyond the direct loss of fruit, additional costs stemming from bird damage include:
- Higher pesticide use to control insects attracted to damaged fruit
- Greater susceptibility of damaged fruit to rot and disease
- Increased picker labor to discard ruined fruit
- Lower market prices due to scarred, imperfect fruit
Taking action to deter birds is an important investment to protect crop yields and ensure farm profitability.
Physical barriers to keep birds out of trees
Physical barriers provide the first line of defense to keep birds off crops. Different barrier options include:
Bird netting
Draping fine plastic or nylon mesh netting over trees creates an impermeable barrier against birds. Netting comes in different mesh sizes, such as 5/8-inch, 3/4-inch or 1-inch. Smaller mesh is preferable to help exclude smaller bird species. Advantages of bird netting include:
- Effective protection when installed properly
- Long lifespan with proper maintenance
- Allows sunlight and rainfall to reach trees
Key challenges with netting include cost, labor to install/remove annually, and risk of entanglement with deer and other wildlife. Securing the netting tightly to prevent sagging pockets is essential.
Aluminum foil strips
Suspending reflective aluminum foil strips around trees creates noise and reflection that deters birds. The strips should be at least 1 inch wide and spaced no more than 5-6 inches apart. Effectiveness is often short-lived as birds become accustomed to the deterrent.
Scare tape
Scare tape (also called flash tape or bird tape) consists of reflective strips of Mylar plastic on a twistable line. When strung through trees, the flashing strips scare birds with an unpredictable shimmering effect. Like foil strips, birds can become habituated, so scare tape works best in combination with other methods.
Auditory bird deterrents
Noise-making devices trigger birds’ innate fear response to distress calls and predator sounds. Different auditory options include:
Propane cannons
Propane-powered cannons create loud explosions at programmed intervals (e.g. every 20-30 minutes). The sporadic nature helps prevent birds from becoming accustomed. Users can vary the firing sequence and move cannons around the orchard.
Predator vocalizations
Broadcasting recorded calls and cries of predator species like hawks, falcons and owls induces a warning response in many bird types. Vocalizations are most effective when used judiciously and varied to prevent habituation.
Harassment with noisemakers
Making loud disruptive sounds using clapper devices, bangers, sirens or other noisemakers when flocks arrive helps scare birds away from the area. Combining harassment with other deterrents is more effective than noise alone.
Visual bird deterrents
Visual devices take advantage of birds’ natural wariness using threatening images of predators or distress. Options include:
Scarecrows
Traditional scarecrows placed conspicuously in orchards work to frighten descending flocks. More modern variations use automatic moving parts to enhance the fear factor. Scarecrows should be moved regularly to remain effective.
Predator decoys
Lifelike replica hawks, owls, snakes and other predators discourage birds from lingering. Motion-activated flapping owl decoys often elicit the best response. Sitting decoys should be repositioned frequently.
Reflective ribbons and balloons
Suspending shiny metallic ribbons or large balloons imprinted with large eyes creates discomfort and distraction for birds. The unfamiliar objects hinder birds from focusing on fruit. Effectiveness is temporary without reinforcing with other deterrents.
Distress decoys
Fake dead birds or taxidermy mounts of distressed birds warn flock members of danger. Projecting the distress of fellow birds triggers an innate desire to avoid threat. Distress signals must remain novel by relocating decoys.
Chemical bird repellents
Chemical taste or sensory repellents make fruit less palatable using irritants, taste deterrents or non-toxic chemicals. Repellents approved for organic use include:
Anthraquinone-based products
Naturally-occurring anthraquinone causes stomach irritation when ingested by birds. Registered anthraquinone products include Avipel and FlightControl Plus.
Methyl anthranilate
This grape-flavored compound temporarily overwhelms bird taste receptors. Examples include Rejex-It Fog Force and GWN-80.
Vegetable oils
Naturally-derived oils like corn and rapeseed oil coat fruit with a non-toxic, distasteful film. Vegetable oil sprays need frequent reapplication.
The effectiveness of chemical repellents depends on thorough coverage and proper reapplication. Heavy rainfall can wash away applications.
Trapping problem birds
Selective trapping and removal of abundant bird species may provide temporary relief in extreme cases. Trapping programs should only be done under guidance of the U.S. Fish and Wildlife Service and state wildlife agencies. Maintaining traps, humanely euthanizing birds and properly disposing of carcasses also presents challenges.
Falconry
The use of trained hawks, falcons and eagles to chase and scare nuisance birds is an emerging method adopted by some commercial growers. Falconry requires specialized expertise, permits and imposes extra costs. Effectiveness and practicality for smaller operations remains unclear.
Integrated pest management approach
The most effective bird control programs integrate multiple deterrent techniques in a tailored pest management system. This creates an unpredictable environment to which birds cannot acclimate. Components of an integrated plan may include:
- Physical exclusion with netting early in season
- Noisemakers and distress calls during ripening
- Visual deterrents like flash tape, balloons and scarecrows
- Repellent sprays as an added layer near harvest
- Trapping for specific high-pressure species
Careful scouting and monitoring helps determine seasonal patterns and inform a dynamic plan responding to changing pressure. A program coordinator should direct efforts and vary techniques to sustain efficacy. Successful application requires appropriate investment in equipment, maintenance and labor.
Combining approaches by fruit type
Recommended integrated plans will differ based on the fruit grown:
Cherries
- Netting for starling exclusion in spring
- Propane cannons and distress calls when ripening begins
- Methyl anthranilate spray prior to harvest
Grapes
- Netting just before veraison
- Automated cannons and predator decoys
- Foil strips and flashing tape through ripening
- Trapping for stubborn flocks
Blueberries
- Bird netting over bushes in fruit development stage
- Predator cries alternating with noise harassment
- Scarecrows moved weekly
- Pyrotechnic bangers as needed for large flocks
Apples
- Netting outer rows early
- Distress decoys visible in trees
- Reflective ribbons across orchard
- Methyl anthranilate coating before harvest
Cost considerations
The costs to deter birds include:
- Equipment purchase – cannons, distress call systems, netting, decoys, etc.
- Consumable supplies – propane, ammunition, tape/ribbons, repellents
- Labor for installation, monitoring, maintenance and removal
- Ongoing coordination by trained program manager
These costs are offset by savings from reduced crop losses. With proper implementation, most operations experience a positive return on investment in bird control.
Method | Equipment Cost | Consumable Cost | Labor Cost |
---|---|---|---|
Netting | $400-$1000 per acre | Minimal | High – Install & remove yearly |
Propane cannons | $500-$1500 each | $5-$15/week for propane | Moderate – Move cannons, fill propane |
Distress calls | $100-$300 per unit | Minimal | Low – Periodic movement |
Scarecrows | $50-$150 per scarecrow | Minimal | Low – Weekly relocation |
Repellent sprays | Sprayer equipment | $75-$200 per acre | Moderate – Annual applications |
Regulations for bird control
Use of bird deterrent techniques must comply with relevant laws and permitting requirements:
- Noise devices like cannons and distress calls may have local noise ordinances dictating use
- Harming birds protected under the Migratory Bird Treaty Act without permits is illegal
- Pesticide spraying must follow label directions for EPA-registered products
- Exclusion netting must be wildlife friendly to avoid entanglement issues
- Trapping requires oversight by the U.S. Fish and Wildlife Service
Responsible, ethical use of control practices is critical. Wildlife officials can guide appropriate, legal implementation.
Conclusion
Bird pressure threatens the productivity and economics of fruit orchards and berry farms. An integrated pest management approach combining physical exclusion, scare tactics, harassment and chemical deterrents provides the most effective protection. Control costs warrant thoughtful investment to support farm viability. Responsible management is imperative for coexistence with wildlife.