Perspectives in ornithology: Competition in the air: Birds versus aircraft

Auk, The, Jul 2002 by Sodhi, Navjot S

In addition to predicting the bird hazard, the education of the relevant personnel is the key to success in reducing the bird hazard at airports. A three-day course is offered for military and civilian airport personnel in the United Kingdom. The course content includes bird biology, habitat management, dispersal techniques, and data recording and analysis (Deacon 2000). The ICAO sponsors bird hazard workshops with similar objectives.

There has been a concern that inadequate resources are allocated for studying and solving bird-aircraft conflict (Short et al. 2000). Predicting and avoiding the bird threat to aircraft are critical issues, and more research is certainly needed to fine-tune the existing models and techniques. Educating the relevant personell is equally important so that effective management is implemented

MANAGEMENT

The ICAO recommends that airports should take steps to both monitor and reduce the bird hazard to aircraft. Each airport has its own specific bird hazard problems that depend on the bird species involved, and the habitat types within and surrounding the airports. Hence, a single management recipe that applies across all airports is not possible.

Bird management can be broadly grouped into short-term or long-term action. Short-term action includes scare tactics (e.g. the playing of distress calls) and shooting. Long-term management includes habitat modifications so that airfields and their surroundings become less conducive for birds. One of the problems with short-term control action has been habituation. Birds usually become habituated to bird distress calls within four to six weeks, and reach pretrial numbers in eight weeks (Baxter 2000). The other problem is that birds usually stay in an area before and after the use of calls. The removal of birds through trapping and culling has been practiced at various airports (Blokpoel 1976). However, bird removal can also pose problems because more hazardous individuals that are naive about aircraft might replace experienced residents. That may be counterproductive, but the removal of juveniles can still be effective.

Innovative methods have sometimes been used to counter the bird hazard. For example, border collie dogs (Canis familiaris) are being used to chase birds from airfields (e.g. Southwest Florida International Airport at Fort Myers; Ryan 1999). Such an effort at the Vancouver International Airport in Canada resulted in a 40% reduction of bird numbers over a year (Patterson 2000). Similarly, in Canada, trained Peregrine Falcons (Falco peregrinus) and Gyrfalcons (F rusticolous) have been used to drive birds away from airports during daylight hours (Solman 1973). However, that technique has limited value for airports that have flights during the night and during adverse weather conditions.

In the United Kingdom, all airports are recommended to maintain grass at 20 cm high (Smith 1986). That is based on the assumption that most birds are reluctant to feed in tall grass areas because of difficulty in effectively scanning for predators. However, such grass can result in a high population of small mammals, which can attract birds of prey. Heathrow Airport in the United Kingdom has recently been experiencing problems due to growing numbers of Canada Geese. Pilots have been warned of these birds, and nearby farmers around this and other British airports are being educated to make their properties less inviting habitats for that species. Canada Geese have also been causing nuisance at British parks, and there is now a program underway to limit their productivity through contraceptive pills and the pricking of eggs. Chemicals have been used to reduce the bird hazard. The Manchester International Airport in the United Kingdom applies lumbricides in the grass on runway edges to prevent earthworms from moving on to the runways and thus attracting birds (Smith 1986). However, the large-scale use of lumbricide is not recommended due to possible harmful effects such as poor grass growth and drainage problems (Allan and Watson 1990).