Modeling road mortality hotspots of Eastern Hermann’s tortoise in Romania

Abstract

bstract. Road-associated mortality can lead to local declines of wildlife populations, and management agencies are actively implementing mitigation measures, especially focused on potential road mortality hotspots. In this study we used a spatially-explicit simulation modeling approach to estimate the hotspots of road mortality for the Eastern Hermann's tortoise (Testudo hermanni boettgeri) within its distribution range in Romania. Using a field experiment, we first evaluated velocities while crossing roads. Adult male tortoises moved faster than females (3.98 m/min vs. 2.51 m/min) which led to higher individual probabilities for females being killed on high-traffic roads (0.61 for females vs. 0.44 for males at traffic levels of 7000 vehicles/day). Both males and females had similar road mortality probabilities for traffic levels <IOOO and >35OOO vehicles/day. Our spatially explicit model suggests that, within the entire Romanian distributional range, the tortoises have an overall risk of road mortality 1.6%, which may have a negative impact on tortoise populations. Using the Getis-Ord Gi statistic, we identified road mortality hotspots with mortality rates of 5-30%, in areas bisected by high-traffic national and European-level roads. Our research is timely in that many low-traffic roads are predicted to have increased traffic associated with tourism activities, thus increasing the overall risk of mortality. We suggest that mitigation measures such as signage and roadside fences associated with underpasses have the potential to limit road mortality of this threatened species within predicted current mortality hotspots.

Influence of Landscape Factors on Amphibian Roadkills at the National Level

“…Regarding amphibians and birds in Thousand Islands Parkway, Ontario, Canada, 79% of roadkills were found in two out of six road sections [67]. Only three road sections in Romania were considered hotspots for tortoises in almost 4000 km of roads [68]. In California and Maine, using Getis-Ord Gi*, 10% of roads were identified as hotspots for mammals [36].…”

Landscape ecology, biogeography, and GIS methods

“…Other studies combined spatial analyses with empirical movement data (i.e. road crossing speed) to identify road mortality risk for Hermann's Tortoises (Testudo hermanni boettgeri; Iosif et al 2013) and mortality hotspots for turtles (Patrick et al 2012) across large geographic extents (1000s of km 2 ).…”

Rewilding European Landscapes

“…However, roads and other human access infrastructure have also a strong impact on wild populations and ecosystems. The most obvious impact is road mortality, shown to affect mammals (Philcox et al 1999;Seiler 2005;Grilo et al 2009), birds (Orlowski 2005), reptiles (Iosif et al 2013) and amphibians (Patrick et al 2012). But impacts of roads, traffic and human access can be much more profound, affecting population and community structure (Habib et al 2007), trophic interactions (Kristan III and Boarman 2003;Whittington et al 2011), ecosystem functioning and structure (Christensen et al 1996;Hansen et al 2005;Rentch et al 2005), and environmental conditions through high pollution levels (Hatt et al 2004).…”