The influence of body-size and diet on road-kill trends in mammals

Abstract

Roads negatively impact animals in a variety of ways. One of the most obvious impacts is vehicle-induced mortality. We have little understanding of the patterns and rates of road mortality for mammals. The aims of this study were to determine representative road-kill rates for local mammal species, compare road-kill rates between mammals of different sizes and diets, and compare patterns of road mortality between seasons. We hypothesized that carnivores would be killed less often than herbivores or omnivores and that medium sized mammals (1.0-10.0 kg) would be killed more often than expected based on their frequency in the area. At least 50% of the mammal species in the study area were impacted by road mortality, representing 21 species from 5 mammalian orders. Carnivores were found less often and medium-sized mammals more often than predicted. Porcupines (Erithizon dorsatum), raccoons (Procyon lotor), cottontails (Sylvilagus floridanus) and striped skunks (Mephitis mephitis) were the most frequent species to be killed. On average, 3.8 mammals were killed per 100 km of road. The road-kill rate varied between seasons and species and peaked in mid June. We also looked across studies to determine general rates of vehicle-induced mortality for mammals and found that an average of 8.8 mammals are killed per 100 km. Given the rapid decline of many mammal species and the consistent increase in vehicle miles traveled, efforts to preserve roadless areas and develop strategies to mitigate the effects of roads on mammals are warranted.

Wild vertebrate roadkill in the Chapada dos Veadeiros National Park, Central Brazil

“…Also, many mammals are nocturnal and/or are scavengers. At night, they are targets for vehicles because they can become blind and immobilized on roads when cars' headlights shine on them (Barthelmess & Brooks 2010). Both the hoary fox (Lycalopex vetulus) and the crab-eating fox (Cerdocyon thous) are commonly hit by cars for this reason.…”

Road effects on habitat richness of the Greek Natura 2000 network

“…Merriam et al 1989;Vos and Chardon 1998), increased mortality (Rosen and Lowe 1994;Fahrig et al 1995;Barthelmess and Brooks 2010), habitat fragmentation and edge effects (Mader 1984;Andrews 1990;Soulé et al 1992;Thiollay 1993' Henjum et al 1994Wigley and Roberts 1994;Jaeger et al 2007;Roedenbeck et al 2007;Spellerberg 1998), invasion by exotic species (Lonsdale and Lane 1994), or increased human access to wildlife habitats (Graham et al 2010), all of which are expected to increase local extinction rates or decrease local recolonization rates.…”

Nest and brood survival of Ring-necked Ducks in relation to anthropogenic development and wetland attributes

“…Roads might also impact nest survival and brood survival differently if the predators most affected by roads are those more terrestrially based (raccoons, skunks, and foxes, Vulpes vulpes), than aquaticbased (mink, Neovison vison and river otter, Lontra canadensis), and terrestrial predators impact nest survival more than brood survival. In a New York study of road-killed mammals, raccoons (15.5%) and striped skunks (10.4%) were among the most commonly found road-killed mammals (Barthelmess and Brooks 2010). By contrast, mink and red fox comprised a small proportion (≤ 1%) of their sample.…”

“…These effects occur up to 200 m from roads and increase with traffic volume (Trombulak and Frissell 2000). Meters of road within 1.6 km of wetland + Greater road density will increase road mortality or avoidance behavior of some predators (Philcox et al 1999, Barthelmess andBrooks 2010). -Greater road density will have a more negative impact on invertebrate food availability for hens.…”