Abstract
Roads are one of the most widespread human‐caused habitat modifications that can increase wildlife mortality rates and alter behavior. Roads can act as barriers with variable permeability to movement and can increase distances wildlife travel to access habitats. Movement is energetically costly, and avoidance of roads could therefore impact an animal's energy budget. We tested whether reptiles avoid roads or road crossings and explored whether the energetic consequences of road avoidance decreased individual fitness. Using telemetry data from Blanding's turtles (Emydoidea blandingii; 11,658 locations of 286 turtles from 15 sites) and eastern massasaugas (Sistrurus catenatus; 1,868 locations of 49 snakes from 3 sites), we compared frequency of observed road crossings and use of road‐adjacent habitat by reptiles to expected frequencies based on simulated correlated random walks. Turtles and snakes did not avoid habitats near roads, but both species avoided road crossings. Compared with simulations, turtles made fewer crossings of paved roads with low speed limits and more crossings of paved roads with high speed limits. Snakes made fewer crossings of all road types than expected based on simulated paths. Turtles traveled longer daily distances when their home range contained roads, but the predicted energetic cost was negligible: substantially less than the cost of producing one egg. Snakes with roads in their home range did not travel further per day than snakes without roads in their home range. We found that turtles and snakes avoided crossing roads, but road avoidance is unlikely to impact fitness through energetic expenditures. Therefore, mortality from vehicle strikes remains the most significant impact of roads on reptile populations.
Highlights
Roads are one of the most widespread human‐caused modifications of habitats, and the global road network exceeds 21 million km of road (Meijer, Huijbregts, Schotten, & Schipper, 2018)
We tested whether reptiles avoid roads at broad spatial scales and whether road avoidance has significant energetic consequences using Blanding's turtle (Emydoidea blandingii) and eastern massasauga (Sistrurus catenatus) as model species (Figure 1)
Our results suggest that Blanding's turtles and eastern massasaugas avoid crossing roads, but do not avoid habitats adjacent to roads
Summary
Roads are one of the most widespread human‐caused modifications of habitats, and the global road network exceeds 21 million km of road (Meijer, Huijbregts, Schotten, & Schipper, 2018). Road avoidance can affect fitness by changing energetic expen‐ ditures of wildlife living close to roads Some species reduce their movement as the footprint of human activity increases (Tucker et al, 2018). Road avoidance behavior has been documented in a range of taxa (Andrews & Gibbons, 2005; Dyer, O'Neill, Wasel, & Boutin, 2002; Laurance, Stouffer, & Laurance, 2004; Proulx, Fortin, & Blouin‐Demers, 2014; Robson & Blouin‐Demers, 2013; Shepard et al, 2013), but these previous studies focussed on single populations and did not estimate fitness costs from increases in energy expen‐ diture. We tested whether reptiles avoid roads at broad spatial scales and whether road avoidance has significant energetic consequences using Blanding's turtle (Emydoidea blandingii) and eastern massasauga (Sistrurus catenatus) as model species (Figure 1). We aggre‐ gated telemetry data for Blanding's turtles and eastern massasau‐ gas in North America and tested two indicators of potential road (a)
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