Disentangling roadkill: the influence of landscape and season on cumulative vertebrate mortality in South Korea

Abstract

This study recorded and analyzed cumulative vertebrate roadkill data on 107 km of roads in rural South Korea and reports the first intensive roadkill study results from Asia. Over 30 months, roadkill strikes and adjacent landscape factors were recorded daily or every other day on three types of roads: highway, local, and riverside. For analysis, roads were segmented into 250-m units, and roadkill hotspot segments were calculated with the Getis–Ord Gi* statistic. Eighteen road characteristics and landscape factors were correlated to roadkill hotspots using multiple logistic regression analysis. Mammal mortality increased from spring to fall, whereas bird mortality peaked in summer. Reptile and amphibian mortality peaked during fall. Seasonal focal species’ mortality tracked the taxonomic groups they represent, except oriental scops owl (Otus scops), for which yearly mortality peaked 2 months earlier than for most birds. Mammal and bird roadkill hotspots were concentrated on the highway, which passes across mountains, whereas amphibian and reptile hotspots were on the riverside road because of movements related to breeding, juvenile dispersal, and hibernation. However, many species used the spatially complex agricultural fields along the local road, especially during harvest season. The significant site and landscape factors that influenced overall roadkill hotspots were a high landscape percentage of water and rice paddies, low traffic volumes, high percentage of natural vegetation, an absence of road banking, high roadside grass presence, and an absence of drainage. South Korea has an active wildlife-crossing management program, and these findings can inform avoidance, minimization, and mitigation strategies and practices.