The road of >1000 corpses: landscape and road-related features that promote mortality in the Amazon

Abstract

Roads impact wildlife around the world; however, dedicated studies are lacking in many biodiverse areas such as the Amazon. Identifying which species are more often hit by vehicles and which landscape and road-related features promote roadkill is essential to guide future development and ensure adequate mitigation actions. For six months, we monitored 240 km of roads in the Ecuadorian Amazon and recorded 1125 dead vertebrates (148 species). Reptiles were the most affected class with 380 individuals (56 species), followed by amphibians with 278 individuals (11 species), birds with 259 individuals (62 species), and mammals with 208 individuals (20 species). We used Random Forest models to explore the role of various land cover types and road sinuosity on the observed mortality. Additionally, we created heatmaps to visualize the road segments where roadkills were more frequent. For all vertebrates, mortality was more likely in straight road sections near rivers. The effect of other variables was taxa-specific. Amphibian mortality was more likely near bare soil or forest, birds and mammals died more often near herbaceous-shrubby vegetation, whereas reptile mortality occurred more often further from herbaceous-shrubby vegetation. Road segments with a high mortality (roadkill hotspots) varied across taxa. These hotspots identify areas where further research is needed to assess road impacts and where mitigation could prevent collisions. Among records, we found rare and threatened species, including some that may be new to science. Roadkill surveys not only aid in quantifying threats and informing future planning but can also provide insight into local biodiversity.

First national assessment of wildlife mortality in Ecuador: An effort from citizens and academia to collect roadkill data at country scale

“… Ecuadorian road network (primary and secondary roads) highlighting the sites and roads where systematic studies were conducted and the total number of roadkill records per taxonomic class across all studies. For the Napo province, the study area of Medrano‐Vizcaíno, Brito‐Zapata, and González‐Suárez ( 2022 ) covers most of this province (thick purple line), overlapping with the study areas by Filius et al ( 2020 ) and Medrano‐Vizcaíno and Espinosa ( 2021 ), both shown with a white line. …”

“…We compiled 3305 wildlife roadkill records from 10 systematic surveys conducted on Ecuadorian roads. These corresponded to five published papers, four theses, and one unpublished dataset (Medrano‐Vizcaíno, Brito‐Zapata, & González‐Suárez, 2022 ). Georeferenced data were available for eight of these studies and comprised 2744 roadkill records.…”

“…Systematic survey studies were not only rare but also geographically biased (Figure 1), with three studies conducted in the Napo province (Filius et al, 2020;Medrano-Vizcaíno, Brito-Zapata, & González-Suárez, 2022;Medrano-Vizcaíno & Espinosa, 2021), two in Galapagos (García-Carrasco et al, 2020;Tanner & Perry, 2007), two in Guayas (Armendáriz, 2022;González, 2018), two in Manabi (Gaón & Valdez, 2021;Zavala, 2020), and one in Azuay (Aguilar et al, 2019).…”

“…F I G U R E 2Location of all roadkill records compiled from citizen science and other sources and total number of records for each taxonomic Class and province onomic uncertainties and unknown conservation status for many of them(Cisneros-Heredia, 2005;IUCN, 2022;Wilkinson, 2012).Both groups were frequently detected across three studies in Napo(Filius et al, 2020;Medrano-Vizcaíno, Brito-Zapata, & González-Suárez, 2022;Medrano-Vizcaíno & Espinosa, 2021), and nonsystematic data included 41 records of Atractus sp. snakes.…”