Population Increases of Large Birds in North America Pose Challenges for Aviation Safety

There is a strong correlation between bird mass and the likelihood of aircraft damage during a bird–aircraft collision. Thus, the U.S. Federal Aviation Administration (FAA) has established airworthiness standards related to bird mass for engines, airframes, and windshields. Most standards use large (1.8 kg) and medium (1.1 kg) birds as benchmarks (the empennage and certain large turbofan engines use a 3.6-kg bird). There are 20 large (≥1.8 kg) and 16 medium (1.1–1.7 kg) bird species in North America with ≥20 strikes reported for civil aircraft (FAA National Wildlife Strike Database), 1990 to 2018. I analyzed the population changes of these 36 species from 1990 to 2018 in relation to flocking behavior. For the 20 large species, the combined population had a net gain of 27.8 million birds (129% increase). For the 16 medium species, the combined population had a net gain of 6.7 million birds (20% increase). Notably, all 9 species with body mass ≥3.6 kg indicated population increases. In agreement with the increased numbers of birds, the number of strikes involving large and medium birds showed significant (P < 0.01) positive trends from 1990 to 2020 as did strikes involving multiple birds. The threat to aviation safety from large and medium birds, especially flocking species, was much higher in 2018 than in 1990. Although progress is being made to mitigate the risk by management programs to keep large and medium birds away from airport properties, these actions do little to mitigate the threat during climb and approach phases of flight. Enhanced airworthiness standards for aircraft components, bird-detecting radar to provide real-time warnings, and aircraft lighting schemes to improve visibility of aircraft to birds are priority areas of research and development to mitigate these off-airport threats to aviation safety.