Bird Strike Committee Proceedings
Date of this Version
May 1999
Document Type
Article
Abstract
Changes in bird populations have been recognised as affecting the risk to aircraft of a bird strike. However, in terms of bird strike prevention, changes are generally only considered at the local level i.e. reducing the number of birds on the airfield. At a national level, concern has been expressed about recent increases in waterfowl, particularly geese, and the implications that this may have for flight safety, and management of the risk. However, although work is currently being undertaken to investigate if higher numbers of large waterfowl are causing an increased risk to safety (Allan, Bell & Jackson in press), the work is being hampered by incomplete reporting, and lack of information on world-wide population trends. There has been little discussion of the implications of declining populations to the bird strike risk. This is in part because it is not perceived as a problem. However, it could be argued that if the risk is not recognised to have changed, then resources will continue to be allocated to try and deter a species from using airfields, which no longer warrants a high priority because of its declining numbers. Through this, it has been assumed that an increase in population will lead to an increase in risk and that a decrease in population will lead to a reduction of risk. However, birds are not randomly distributed across the countryside, and there may be behavioural factors which mean that this is not the case. The Northern Lapwing (Vanellus vanellus ) is a wader species commonly found on UK airfields. Because of its size, and its habit of forming large flocks, it is usually considered as a particularly hazardous species. It is also frequently involved in bird strikes and for the years 1976-1995 was the most commonly struck species in the UK. Between these years 1704 strikes were reported in the UK, comprising 17.4 % of all strikes. It is fortunate that in the UK, long term population monitoring of many of the common breeding species has been carried out for a long period of time. This has allowed a long-term decline in the Northern Lapwing population in the UK to be monitored and investigated (Marchant et al 1990, Shrubb & Lack 1991 O’Brien & Smith 1992) Declines have also been reported in other areas of Europe (Hötker 1991). These declines are believed to be due to changes in agricultural practice which have limited breeding site availability and reduced breeding success (Baines 1988, Galbraith 1988). It could be expected that this would have an effect on the status of Northern Lapwings on airfields, thus reducing the risk from this species. However, it has also been suggested that the number of strikes involving Northern Lapwings would be mainly unaffected, because airfields are preferred sites (Milsom 1990) and declines might be expected to occur in other less optimal locations first. Over the same period, airfield habitat management and bird control practices have improved in the UK (Milsom & Horton 1995). This would also reduce the number of Northern Lapwings to be found on airfields, and consequently, the number of strikes involving Northern Lapwings would be expected to decrease. This paper examines the incidence of strikes involving Northern Lapwings between 1976-1995, and assesses firstly, if there was any change in numbers, and secondly, attempts to determine the major cause of any alteration in the strike rate.