Biogeographical patterns in the seasonality of bird collisions with aircraft.
Abstract
Bird collisions with aircraft pose a serious threat to human safety. However, broad-scale patterns in how bird strikes might vary through space and time have yet to be fully understood. Here, we conducted a biogeographical study of bird strikes to answer two questions: (1) Are bird strikes higher at certain times of the year in the Northern and Southern Hemispheres? and (2) Is seasonality in bird strikes more prominent in the Northern Hemisphere than in the Southern Hemisphere? To answer these questions, we collated data on monthly bird strikes from 122 airports across the globe and used circular statistics to test for hemispherical asymmetries in the circular mean and variance in bird strikes. Results showed that annual peaks in bird strikes occurred between late summer to autumn seasons, and as a result, they occurred at opposite times of year in the northern and southern hemispheres. Results also showed that bird strikes were more seasonal in the Northern Hemisphere than in the Southern Hemisphere, where strikes tended to occur more consistently throughout the year. Practical implication: Overall results indicate that avian collisions with aircraft show strong biogeographical patterning, concomitant with global patterns in bird breeding seasons and migration tendencies.