Factors affecting pilot-reported bird-strike rates at Christchurch International Airport, New Zealand

Pilots' reports of their aircraft striking birds or having near misses at Christchurch International Airport from 1981 to 1993 were analysed to identify factors influencing the rate of such incidents. A preliminary analysis indicated that reporting of near misses was not influenced by recent bird strike incidents, which suggested that the data were reasonably robust to variation in pilot awareness of the problem. A total of 362 strikes was reported during the survey period, most commonly involving sparrows and gulls. Pilots were more likely to report near misses if the birds were large (e.g., gulls Larus spp., spur-winged plover Vanellus miles novaehollandiae, white-backed magpies Gymnorhina spp., and Australasian harrier Circus approximans) than if they were small (e.g., sparrows Passer domesticus and finches Carduelis spp.). The risk of an aircraft being struck varied both diurnally and seasonally, being highest at 0800-1000 h and in April. Birds seemed better able to avoid Boeing 737s than the quieter Boeing 767s and Whisper Jets. Bird-strike rates increased progressively in the early and mid 1980s, but this increase appears to have been halted through an intensive bird management programme in place since 1987 and restrictions on agricultural activity and urban refuse near the airport. However, quarterly bird-strike rates have been significantly more variable since 1987; the reason for this is unclear. A preliminary cost/benefit analysis of this management programme is presented.