Road- related features that promote mammal road crossings

Abstract

This master’s thesis was written in the format of a scientific paper in the English language. The aim was to evaluate which road-related features promote a higher incidence of mammal crossings, and if they vary among species or groups of species (carnivores and ungulates). Telemetry data from 14 mammal species, provided by different researchers, were used to identify 500m road segments with the highest and lowest incidence of crossings. Subsequently, twelve road-related features (number of lanes, presence of exclusion fence, exclusion fence height, presence of stream crossing, stream in parallel, road topography, distance to the nearest curve, road verge structure, connectivity of open and closed areas, and percentage of open and closed areas) were analyzed in 2201 road segments using Google Street View. We ran the results to ten Generalized Linear Mixed Models of binomial family, or Generalized Linear model in some cases (1 - all mammals, 2 - all ungulates, 3 - all carnivores, 4 - brown bear from Canada, 5 - brown bear from Greece, 6 - cheetah, 7 – cougar, 8 - Eurasian lynx, 9 - roe deer, and 10 - wapiti). The high/low incidence of crossings was the response variable, and road- related features were the explanatory variables, with species interaction and study area as random variables. The results showed that mammal crossing incidence is lower when there are more lanes on the road, and when a stream crosses the segment. The incidence of crossings was higher away from a curve. Although we did not find a rod feature that was significant for all models, some features had effects on few models. The distance to the nearest curve increased the number of crossings in mammals, carnivores, and brown bears from Canada, while the number of lanes decreased the incidence of crossings in mammals in general, carnivores and ungulates. Furthermore, the distance from the stream in parallel had a negative effect on carnivores and ungulates, and a positive effect on cheetahs and wapiti. Connectivity of open areas resulted in more crossings for brown bears from Greece and roe deer, but decreased for pumas and Eurasian lynx. Due to the lack of consistency in the road features related with high incidence of crossings, werecommendanalyzing the effects of roads by species.