Birds and airplanes don’t mix. Bird strikes cost the aviation industry over $1.2 billion annually and can cause catastrophic accidents. That’s why airports go to great lengths to keep birds away from runways and flight paths. Let’s take a look at the most common techniques airports use for bird control.
Why Birds Are a Problem for Airports
Birds flock to airports because large, open grassy areas next to bodies of water provide ideal habitat. Airports often displace birds’ natural habitats, and tall structures offer safe perching locations. Meanwhile, jet engine exhaust, emissions, and turbulence stir up insects that birds feed on.
Collisions between birds and planes, known as bird strikes, are a significant safety and economic concern. Around the world, bird strikes destroy 9-24 aircraft annually. Engines are designed to withstand ingesting birds up to certain sizes, but strikes can still cause power loss, damage flight controls, and break through cockpit windows. Bird strikes killed over 250 people worldwide between 1988 and 2018.
In addition to catastrophic accidents, bird strikes cause costly delays and repairs. One study estimated that bird strikes cause $1.2 billion in damage to the global aviation industry every year. In the U.S. alone, bird strikes cause around $800 million in damage annually.
Habitat Modification
One of the most effective long-term methods is modifying the airfield environment to make it less attractive for birds. This limits the number of birds that will try to access the area in the first place.
Common habitat modification strategies include:
- Removing standing water, draining wetlands, and leveling uneven terrain that could provide nesting sites
- Mowing grass frequently to keep it short, eliminating protective cover
- Thinning out trees, bushes, and shrubs that offer food sources and perches
- Covering ponds with netting to prevent birds from landing
- Installing gravel or pavement instead of grass or bare dirt in key areas
While this approach is very effective, it can be expensive due to the scale of modification required. It also raises environmental concerns, as it damages natural ecosystems that support diverse bird populations.
Noise Deterrents
Birds are startled by loud noises, so airports use various sound-based tools to repel them. These include:
- Propane cannons that create booming explosions at random intervals
- Recorded distress calls that frighten birds by mimicking sounds of predators or birds in danger
- Ultrasonic high-frequency devices that emit discomforting sounds humans can’t hear
- Pyrotechnics such as shell crackers, bird bombs, and screamers that produce flashes and loud bangs
The advantage of noise deterrents is they actively move birds away without harming them. However, birds can become habituated to regular noises over time, so airports have to vary the sounds and frequencies used.
Visual Repellents
Visual repellents take advantage of birds’ innate fear of predators and unfamiliar objects. Different techniques are used to scare birds with threatening sights, including:
- Lifelike predator decoys, like robotic hawks and alligators
- Scary-looking effigies of birds in distress
- Mylar tape, shiny balloons, and reflective surfaces that disturb birds
- Laser lights that disperse birds nighttime
Movement and unpredictability make visual repellents more effective. Airports might install motorized decoys that suddenly pop up or use remote-controlled boats to chase birds away from ponds.
Physical Barriers
Fences, wires, nets, and spikes physically prevent birds from accessing certain areas. Different types of barriers include:
- Fishing line strung in criss-cross patterns over ponds and roosting areas
- Sticky gels that glue birds’ feet to surfaces, humanely immobilizing them for relocation
- Low-voltage electric grids that deliver a mild shock
- Spikes or coils on ledges and rooftops to block perching
- Netting over hangars, ponds, and far end of runways where birds congregate
The problem with barriers is they can be expensive to install and maintain, and birds still find ways around them. Used alone, they don’t reliably keep birds away from airports.
Chemical Repellents
Chemical repellents use taste or smell to discourage birds from settling in an area. Common products include:
- Methyl anthranilate spray, which has a grape flavor that irritates birds
- Fogging with essential oils, such as cinnamon and eucalyptus, that birds avoid
- Rotten egg or garlic scent that creates an inhospitable environment
A downside is these products must be reapplied frequently to remain effective as the chemicals dissipate. Chemicals can also kill vegetation and insects, creating a negative environmental impact.
Falcons and Dogs
Some airports employ trained predators to scare birds away from runways and persuade them not to return. Examples include:
- Falconry using hawks, eagles, and falcons to swoop at birds or chase them in flight
- Border collies that herd and stalk groups of birds away from the airfield
The benefit of trained predators is they actively chase birds from the environment while reinforcing not to return. However, continuous presence is required to keep birds away long-term.
Trapping and Relocation
When birds become problematic at a specific location, airports might capture and relocate them. Methods include:
- padded leghold traps that harmlessly restrain birds for transport
- mist nets that tangle birds for collection
- funnel traps for containing live-caught birds unharmed
- chemical immobilization (anesthetizing birds for transport)
While trapping removes problem birds, it’s time-consuming and birds often return. Lethal control such as shooting or poisoning is restricted and used only for extreme safety hazards.
Population Control
Reducing bird reproduction can help limit population growth and minimize long-term risks. Strategies include:
- Oiling or puncturing eggs in nests to prevent hatching
- Removing nesting areas and food sources to inhibit breeding
- Releasing sterilized birds that continue defending territories without offspring
Population control measures are controversial because they interfere with natural reproduction and survival. But they may stabilize populations at lower, less hazardous levels.
Integrated Bird Management
Since no single method keeps birds away completely, airports combine multiple techniques for better results. An integrated bird management plan consists of:
- Habitat modification to reduce carrying capacity
- Active harassment and deterrents for immediate effect
- Exclusion barriers denying access to key areas
- Population control to limit future increases
Coordination is key. For example, noise cannons might initially flush birds from a runway, while habitat changes and falconry prevent their return over time. Plans must be continually evaluated and adapted to respond to changing conditions.
Trends and Technology
New technologies are enhancing airports’ ability to monitor birds and deploy deterrents. Some innovations include:
- Radar and thermal imaging to track real-time bird movements and numbers
- Drones that fly over airfields mimicking raptors and spraying repellents
- Machine learning to analyze bird patterns and optimize harassment
- Smart speaker systems that broadcast varying sounds and frequencies
- Autonomous robotic falcons that run on AI
While technology can enhance effectiveness, skilled technicians are still needed to oversee operations, maintain equipment, and continuously adapt strategies.
Case Study: John F. Kennedy International Airport
John F. Kennedy International Airport (JFK) is located next to Jamaica Bay Wildlife Refuge in New York City. Its location by open water and marshlands makes it a hotspot for bird strikes. To address the problem, the airport has implemented an extensive integrated bird management plan.
JFK’s wildlife biologist oversees bird control full-time. Habitat modification measures include eliminating standing water, cutting long grass, and thinning trees and brush in flight paths. Over 6 miles of trench drains and exclusion fencing have been installed. Pyrotechnics, propane cannons, distress calls, lasers, and other harassment tools are routinely deployed.
The biologist also monitors wildlife using radar and thermal cameras. Data collected guides daily patrols and targeted deterrent use when flocks are detected. As a result, the bird strike rate at JFK has declined by 70% over 20 years while air traffic increased.
JFK’s program demonstrates that proper resource commitment and a customized strategy tailored to the environment allows major airports to reduce bird strike hazards.
Conclusion
Keeping birds away from airports requires diligent, integrated efforts. While no single tool solves the problem completely, combining habitat management, active deterrents, barriers, population control, and technology allows airports to significantly reduce bird hazards. As air travel continues increasing worldwide, managing wildlife and preventing bird strikes is crucial for efficiency and safety.