Abstract
One of the most evident and direct effects of roads on wildlife is the death of animals by vehicle collision. Understanding the spatial patterns behind roadkill helps to plan mitigation measures to reduce the impacts of roads on animal populations. However, although roadkill patterns have been extensively studied in temperate zones, the potential impacts of roads on wildlife in the Neotropics have received less attention and are particularly poorly understood in the Western Amazon. Here, we present the results of a study on roadkill in the Amazon region of Ecuador; a region that is affected by a rapidly increasing development of road infrastructure. Over the course of 50 days, in the wet season between September and November 2017, we searched for road‐killed vertebrates on 15.9 km of roads near the city of Tena, Napo province, for a total of 1,590 surveyed kilometers. We recorded 593 dead specimens, predominantly reptiles (237 specimens, 40%) and amphibians (190, 32%), with birds (102, 17%) and mammals (64, 11%) being less common. Recorded species were assigned to three functional groups, based on their movement behavior and habitat use (“slow,” “intermediate,” and “fast”). Using Ripley's K statistical analyses and 2D HotSpot Identification Analysis, we found multiple distinct spatial clusters or hotspots, where roadkill was particularly frequent. Factors that potentially determined these clusters, and the prevalence of roadkill along road segments in general, differed between functional groups, but often included land cover variables such as native forest and waterbodies, and road characteristics such as speed limit (i.e., positive effect on roadkill frequency). Our study, which provides a first summary of species that are commonly found as roadkill in this part of the Amazon region, contributes to a better understanding of the negative impacts of roads on wildlife and is an important first step toward conservation efforts to mitigate these impacts.
Highlights
Understanding the negative effects of roads on wildlife is of increasing importance in a world with rapidly expanding road infrastructure (Laurance et al, 2014)
Expanding on the influence of landscape on roadkill prevalence, we predict that (e) roadkill decreases in abundance and diversity as distances to patches of protected high-quality habitat increases, as we hypothesize that high-quality native habitat harbors relatively high density and diversity of wildlife that can be subject of vehicle collision; a pattern that we predict to be supported by the lack of wildlife in areas with more human disturbance, such as urban centers, as observed previously by Carvalho and Mira (2011)
We found that the distance to Reserva Biológica Colonso Chalupas (RBCC) (p < .001, D2 = 0.303) had a significant positive effect, while the distance to the cities Archidona and Tena (p < .001, D2 = 0.285) had a significant negative effect on the number of roadkill for species belonging to the group “slow.” Speed limit had a significant positive effect on the number of roadkill for the group “intermediate” (p < .001, D2 = 0.109) and “fast” (p < .001, D2 = 0.299) (Table S2)
Summary
Understanding the negative effects of roads on wildlife is of increasing importance in a world with rapidly expanding road infrastructure (Laurance et al, 2014). Other studies on roadkill, especially those set in the Neotropics (e.g., Coelho et al, 2012; Freitas et al, 2010; Teixeira, Coelho, Esperandio, & Kindel, 2013; Teixeira, Coelho, Esperandio, Rosa Oliveira, et al, 2013), might allow us to derive some generalities, we do not have any actual data on roadkill in the western Amazon, the part of the Amazon where human encroachment through road expansion is highest (Lessmann, Fajardo, Muñoz, & Bonaccorso, 2016; Mena, Lasso, Martinez, & Sampedro, 2017) To provide such initial data, and to start a body of literature which may aid the effective implementation of roadkill mitigation efforts in this biodiverse part of the world, we quantified roadkill incidents on two roads in the Ecuadorean Amazon. Expanding on the influence of landscape on roadkill prevalence, we predict that (e) roadkill decreases in abundance and diversity as distances to patches of protected high-quality habitat increases, as we hypothesize that high-quality native habitat (in our study represented by a protected area) harbors relatively high density and diversity of wildlife that can be subject of vehicle collision; a pattern that we predict to be supported by the lack of wildlife in areas with more human disturbance, such as urban centers, as observed previously by Carvalho and Mira (2011)
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