Strain by the train: Patterns of toad fatalities on a Brazilian Amazonian railroad

Abstract Transportation infrastructures are directly responsible for killing billions of animals worldwide. Although the understanding about road impacts have recently increased, the impact of railroads on wildlife has received less attention. The current knowledge concerning the impacts of railroads focuses mainly on large mammals although amphibiansmight be affected. Our study aims to unravel temporal and spatial patterns of Rhinella toad fatalitieson a Brazilian Amazonianrailroad, to comprehend how toadsare killed and to estimate the magnitude of toad fatalities. Data collection was carried out on foot on an 871-km stretch of the Estrada de Ferro Carajas from 2013 to 2017. We identified different potential causes for fatalities: being run over, desiccated or with barotrauma signs. We estimated a surprisingly high carcass persistence probability of about 38 days. After correcting for the bias from carcass detection and removal, we estimated that approximately 10,000 toadsare killed per year (≈ 11 fatalities/km/year). A GLM model showed that toadswere more likely to be killed in the dry to wet transition. We identified critical zones of fatalitiesand prioritized them according to their intensity. The highly critical segments encompass >10% of all fatalitiesalthough they cover only 1.5% of the railroad. Our study is the first one to address carcass detection and persistence on railroads and to unravel patterns of fatalitiesof an amphibianspecies in a tropical climate. A better understanding of the patterns of animal fatalityon railroads is of fundamental importance to manage and mitigate this impact.