Temporal and Age-Dependent Patterns of Road-Killed Raptors in Argentina

Abstract

Vehicle collisions are a common cause of death for many species. Collision risks may be particularly high for species that feed on road-killed animals or forage in areas adjacent to roads, particularly for inexperienced immature individuals. We examined the species and age composition of road-killed diurnal raptors found while driving in Argentina from 2021 to 2023. We mainly assessed temporal and age-dependent mortality of Crested Caracaras (Caracara plancus), although we also report six other raptor species killed by vehicle collisions in Argentina. Most raptor road collisions involved obligate or facultative scavengers, likely because of their tendency to use roads and adjacent areas for feeding on other road-killed fauna. The most frequent species found road-killed was the Crested Caracara, followed by the Chimango Caracara (Milvago chimango). We found immature Crested Caracaras most frequently during austral summer (December and January), likely due to the annual pulse of post-fledging and dispersing juveniles. Understanding of the factors influencing vehicle collision risk for raptors in South America remains limited, and additional research is warranted.