Adopting an integrated, flexible approach to reducing the birdstrike risk from Canada geese

Canada Geese overflying the runways at London’s Heathrow Airport have been struck on eleven occasions by aircraft during the last ten years. Four of these occurred during the pre-breeding season and seven during the post moult period. A monitoring study was initiated in 1999 to evaluate the movements of geese around the airport and determine appropriate mitigation strategies to reduce the risk of birdstrike. Moult sites within 13km of the airport were identified. 4,900 moulting geese were caught and fitted with colour rings and radio-transmitters between 1999 and 2004. 2,500 visits were made to over 300 sites resulting in over 10,000 sightings of known individuals. Birds that crossed the airport approaches whilst moving between roost sites and feeding areas in newly harvested cereal crops were identified. Throughout the monitoring period efforts were made to control the risk, but by 2003 it was estimated that 10,000 bird transits of the approaches involving almost 700 individuals occurred during a 50 day period. The knowledge of the movements of ringed and tagged birds was used to inform a revised habitat management, daily roost dispersal and on-airfield bird deterrence programme in 2004. By adopting a flexible approach to management, an estimated 70% reduction in bird transits was achieved. This paper discusses the techniques used to achieve this reduction.

Bird Depredation

A survey of catfish producers by the United States Department of Agriculture, Centers for Epidemiology and Animal Health (CEAH) in 1996 indicated that the two primary sources of catfish losses in commercial operations were disease (45%) and wildlife (37%) (CEAH 1997a). A variety of avian and mammalian predators are amracred to aquaculture facilities in the United States (Parkhurs: er al. 1992) because ponds and open raceways provide a constant and readily accessible food supply for these animals. However, the mere presence of these predators arcund aquaculture faciliries does not necessarily mean that significant depredation problems are occurring. At catfish farms, three species or species groups of birds are primarily cited by catfish producers as causing most depredation problems (Wywialowski 1999). These include doublecrested cormorants, wading birds (herons and egrets), and American white pelicans, in order of importance to catfish producers (Wywialowski 1993). Although all of these species consume catfish, their biology, distribution, dietary preferences dictare the extent of depredation problems they cause and the approaches needed to alleviate their depredations. With the exception of total bird exclusion from ponds, there are no simple solutions for resolving all bird depredation problems in catfish aquaculture. Thus, in most cases, an integrated management approach to alleviating bird depredations must be considered.