The distribution of vertebrate roadkill varies by season, surrounding environment and animal class

Abstract

Due to rapid human expansion in the last century, wildlife roadkill is becoming a concerning threat to biodiversity and human safety. The frequency of roadkill events depends on factors related to specific traits of the road –fencing, tortuosity, or type of habitat, among others– and the animal ecology –such as activity patterns, reproductive season, thermoregulation– which, in turn, are related to environmental factors (with seasonal variations). Here we assessed roadkill mortality of terrestrial vertebrates over the year. To do this, we sampled 10 road sections (of 3 km, by walk) in the south of Spain for a full year, registering the carcasses of run-over vertebrates. Then, we analysed the spatiotemporal patterns of roadkill events for the four vertebrates’ classes and the effects of road traits (presence of fence, tortuosity, distance to water body) and environmental variables (mean temperature and precipitation). Mammals suffered the highest mortality by roadkill (45.72%). Tortuosity of the road section and precipitation were not related to the number of collisions, while the presence of fences was related to an increase in roadkill events, and mean temperature significantly increased the probability of collision of mammals, birds, and reptiles. There was a seasonal effect in the number of collisions, which spatial pattern depended on the class of vertebrates. All this leads us to conclude that, to reduce the impact caused by roadkill mortality on the wildlife we need specific measures to be taken in each critical place for each vertebrate group.

Anthropogenic, environmental and temporal associations with vertebrate road mortality in a wildland–urban interface of a biodiverse desert ecoregion

“…Temperature may better explain mammalian activity, which diminishes towards the extremes [44,51]. Here, roadkill of endothermic vertebrates as well as reptiles was positively influenced by daily low temperature—a trend observed in these classes elsewhere [38,40,42,92]. Our post-sunset sampling times coincided with when many Sonoran Desert reptiles, especially snakes, increase activity owing to more tolerable temperatures [60,65,68] and nocturnal mammals begin their surface activities [44,94].…”

“…Environmental factors, such as climate, development, traffic and luminosity, are associated with road mortality [37–41]. Roadkill rates can also vary temporally by diel and seasonal activity periods [42,43]. Many herpetofauna and small mammals, for example, employ nocturnal activity strategies to evade the heat of the day in desert climates [38,44]; herpetofauna often use roads for thermoregulation after the sun sets [34,35,45].…”

Wildlife roadkill in Southwestern Ethiopia: Hotspots, drivers, and victim species

“…However, in order to fully understand the impact of season and other factors on roadkill in the Afromontane forest of southwest Ethiopia, long term research is needed to account for the variability. Moreover, some studies reported that there is a seasonal variation in the number of wildlife road kills [ 27 , 28 ].…”