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The bald eagle (Haliaeetus Leucocephalus Alascanus (Townsend)) as an aircraft hazard at Port Hardy Airport

University of British Columbia

A significant bird hazard to aircraft occurs at times at Port Hardy Airport through the presence of numbers of northern bald eagles in the vicinity of the airport and its approaches. This study investigated bald eagle abundance, distribution, movement patterns, productivity and feeding habits within the airport vicinity and satellite region. Findings were analyzed in the light of comparable ecological information available on the species. The study extended from October 1972 to October 1974. The resident summer and winter population within the airport vicinity approximated 3 eagles. Numbers increased gradually from late August until early November (when salmon were spawning in the Keogh River) and when 11 eagles were continuously present. The maximum number of eagles at any one time was 35. Even a relatively small spawning run of salmon was adequate to attract the eagles and the very large runs did not attract eagles in the same ratio. Eagle numbers decreased from early November until the herring spawning season in March and April when at least 5 eagles were continuously present. The potential hazard to aircraft, expressed as the maximum number of eagle sightings and the number of eagles observed per hour, was greatest during the fall salmon spawning season and the spring herring spawning season for each of the 5 observation areas within the airport vicinity. The population within the study area (200-250 resident eagles) was sufficiently large to dismiss a killing program, even if this was socially acceptable. Mean nesting density in the study area was at least .1 active nest/lineal km of coastline with .2 active nest/lineal km of coastline in the airport vicinity. Fifty seven per cent of the nests failed but those that produced young averaged 1.4 young/nest. Five active nests were within the area of airport activity and they did not differ in success rate or fledged young per successful nest from nests more remote. Statistical analysis of distribution data within the airport vicinity revealed that eagle use was significantly greater in the Keogh River mouth region and significantly lower in the inland region than in the remaining observation areas. The aggregation area along the KeoghiiRiver in the southeast flight path for runway 1028 presented the greatest hazard to aircraft. Direct eagle flights across the flight path occurred at frequent intervals in September and October and were often at the same elevation as approaching or departing jet aircraft. Since it is not likely that the behaviour of the eagles can be changed, ways of altering the flight paths of the aircraft were considered so as to lessen the frequency of interaction. This can be done by extension of runway 102 8 (by about 610m) to allow approaching or departing Boeing 737 jets to pass over, instead of through, the hazardous zone above the Keogh River.

Text

2010-03-10

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http://hdl.handle.net/2429/21729

Zoology

University of British Columbia

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