I've previously written about how urban environments appear to generate wildlife somewhat smarter than rural equivalents. In contrast, airports seem to be a very poor choice for birds to inhabit, suggesting that the loss of natural environments coupled with the relatively undeveloped land around airport perimeters is causing birds to congregate in such precarious places.
It's somewhat ironic that such an environmentally unfriendly technology as air travel is inadvertently providing habitats for wild birds, but as urban sprawl increases animals are forced to live wherever they can find, even areas as seemingly unsuitable as runway taxiways and safety areas. As aircraft increase in size and speed but decrease in engine noise, it may be that aviation technology is contributing to the problem. In addition, waterfowl are attracted by the fresh water storage ponds found near runways for use in firefighting or drainage. Therefore, despite the noise, pollution, changes to local weather patterns and the obstacles in the form of the aircraft themselves, airports worldwide have found themselves becoming home to or visited by flocks of numerous bird species.
With over forty bird strikes every day, the cost to the global airline industry surpasses US$1 billion per year. So what is being done to reduce or remove this threat? The range of options is both ingenious and proof that birds are a formidable opponent, so here is a brief summary of popular methods:
- Removing food and water sources
- Audio repellents
- Chemical repellents
- Fake fire and pyrotechnics
- Baited traps
- Real and fake predators
- Removing and culling birds
A substantially less environmentally-friendly approach has been the regular use of insecticides to remove food sources for insectivorous birds and even distributing poison to remove potential raptor prey such as rabbits. Open water storage ponds within airports have been netted to prevent waterfowl from landing on them, but camouflage has also been developed specifically to minimise the attractiveness of large bodies of water.
2) Some airports such as Singapore's Changi play bird distress and/or raptor calls to scare birds away. A less subtle method has been the regular discharge of loud sounds generated by sonic cannon such as propane exploders. However, evidence suggests that birds soon become accustomed to these.
3) As an antithesis to the removal of food sources described above, adding chemical repellents to airport vegetation is now being used. Since 2010, New Zealand airports have been using a a locally-developed grass, which contains an endophyte fungus that reduces insect numbers and makes birds sick. This may prove to be easier to implement than natural chemical repellents imported from agribusiness, such as methyl anthranilate and anthraquinone, which require sophisticated, ongoing and locally-tailored programmes to maintain effectiveness.
4) Although it might sound high-tech, the use of wind-blown metallic streamers that simulate fire have been found to only fool birds for short periods. Likewise, the use of lasers, flare launchers and other live pyrotechnic devices serve to acclimatise local wildfowl to sudden noise and light. After all, the birds are already congregating around noisy aircraft for much of the day!
5) For airports frequented by raptors, live prey such as pigeons can serve as bait for sophisticated traps that notify staff once they have been triggered. The problem then is where to release the bird of prey so that it doesn't return to the original area.
6) The opposite of the previous method is to swamp the locality with trained predators, from dogs to raptors, in order to convince birds to nest elsewhere. The predators don't have to always be live, either: in the USA, fake coyotes have been used in wetlands to keep birds away from flight paths.
7) If all other methods fail, there are several time-consuming alternatives that could be used as a last resort. Firstly, birds can be caught and moved to regions far from airports. Naturally, this requires collaboration with wildlife experts and/or rangers. As a guaranteed solution, culling may also be allowed, although this is hardly going to endear most people to a sector that, essential though it is, has a rather poor environmental record.
One potential smart solution for civilian aviation has been developed for the Royal Netherlands Air Force, which involves constant radar monitoring of wildfowl so that pilots can adjust their take-off and landing flight paths. Apart from lack of the technology at airports, each airport would need long-term trials to determine the appropriate adjustments with regard to local bird populations and their behaviour.
From what I've learnt while researching this issue, there is probably no single solution suitable for all airports; a suite of methods is required, tailored for each one depending on the local landscape, climate and of course bird species - the latter being wily and unpredictable adversaries. Clearly, there's a long way to go if such drastic solutions as culling the birds themselves and poisoning the wider ecosystem are seen as valid options. It looks as if more research is required before the danger to both airliners and birds can be reduced, although I doubt if it could ever be completely eliminated; nature is just too unpredictable!
