Road Ecology Center

Bird-aircraft collisions (hereafter, bird strikes) pose substantial hazards to aviation safety. The most common method employed to objectively quantify bird hazards on airport property is a point-count survey. However, we questioned the adequacy of point counts in prioritizing bird-strike hazards. Our objectives were to 1) quantify relative risk associated with potential bird strikes at Seattle-Tacoma International Airport (SEA) based on data from point counts and a supplemental survey of species time spent within runway protection zones (RPZs) for active runways; and 2) contrast risk based on each survey method against airport-specific bird-strike statistics obtained from the U.S. Federal Aviation Administration (FAA). We defined risk as the product of an index of frequency of use and a damage metric associated with a bird strike. We referenced observational data collected by USDA Wildlife Services biologists (over 50 weeks between 10 June 2003 and 11 June 2004) and assigned 51 species observations to 14 groups based on American Ornithologist’s Union classification and bird-strike data obtained from the FAA. Ranks for risk within survey method were similar between surveys for 9 of 14 groups. Waterfowl (excluding Canada geese, Branta canadensis, but including double-crested cormorants, Phalacrocorax auritus), Corvidae, gulls (Laridae), and Canada geese ranked among the top 5 groups for risk in both surveys. Notably, raptors ranked 4th in risk based on the RPZ survey, but 9th based on point-count survey. Strike statistics for SEA indicate that gulls and some passerine species tied for the most strikes/year (1990-2005), followed by ties among raptors, shorebirds (Laridae), and swallows/swifts (Hirundinidae/Apodidae). Data from the RPZ survey indicate that raptors posed a greater bird-strike risk at SEA than indicated by point-count data. This risk associated with a potential raptor strike was corroborated by strike statistics at SEA.