The role of predictable feeding sources in raptor exposure to airport airspace: A case study of black kites in central Spain

Abstract

Bird-aircraft collisions pose serious safety risks and economic costs, especially near urban areas where landfills attract large numbers of foraging birds. Madrid, home to four airports and Europe's largest known seasonal concentrations of black kites (Milvus migrans) near a major landfill, represents as a potential conflict zone. This study tracked 15 non-breeding black kites using GPS telemetry over three years to evaluate whether their movements compromise aviation safety. Results revealed a strong preference for roosting sites and adjacent landfills, while airports and their surroundings (1, 8 and 13 km buffers) were largely avoided. Flights over airports were infrequent and mostly over the largest airport, likely due to its size and nearby habitat with abundant wild prey. Airport use peak in June, coinciding with maximum numbers of highly mobile immatures and non-breeders (floaters), with midday being the most active period. Use of the study area -including airports and their surroundings-decreased as birds aged. Although black kites were the most frequently recorded species in bird strike incidents at Madrid airports, collisions were low relative to their high local abundance, suggesting a lower-than-expected collision frequency. Nonetheless, targeted habitat management such as reducing prey availability near airports could further mitigate risks posed by black kites and other larger, more hazardous species. This study highlights the value of tracking animal movements to address and solve human-wildlife conflicts in critical infrastructure areas.

Keywords: Airports; Black kites; Collisions; Landfills; Movement ecology; Raptor; Strikes.