Spatiotemporal persistence of bat roadkill hotspots in response to dynamics of habitat suitability and activity patterns

Abstract

Wildlife roadkill hotspots are frequently used to identify priority locations for implementing mitigation measures. However, understanding the landscape-context and the spatial and temporal dynamics of these hotspots is challenging. Here, we investigate the factors that drive the spatiotemporal variation of bat mortality hotspots on roads along three years. We hypothesize that hotspot locations occur where bat activity is higher and that this activity is related to vegetation density and productivity, probably because this is associated with food availability. Statistically significant clusters of bat-vehicle collisions for each year were identified using the Kernel Density Estimation (KDE) approach. Additionally, we used a spatiotemporal analysis and generalized linear mixed models to evaluate the effect of local spatiotemporal variation of environmental indices and bat activity to predict the variation on roadkill hotspot locations and to asses hotspot strength over time. Between 2009 and 2011 we conducted daily surveys of bat casualties along a 51-km-long transect that incorporates different types of roads in southern Portugal. We found 509 casualties and we identified 86 statistically significant roadkill hotspots, which comprised 12% of the road network length and contained 61% of the casualties. Hotspots tended to be located in areas with higher accumulation of vegetation productivity along the three-year period, high bat activity and low temperature. Furthermore, we found that only 17% of the road network length was consistently classified as hotspots across all years; while 43% of hotspots vanished in consecutive years and 40% of new road segments were classified as hotspots. Thus, non-persistent hotspots were the most frequent category. Spatiotemporal changes in hotspot location are associated with decreasing vegetation production and increasing water stress on road surroundings. This supports our hypothesis that a decline on overall vegetation productivity and increase of roadside water deficit, and the presumed lower abundance of prey, have a significant effect on the decrease of bat roadkills. To our knowledge, this is the first study demonstrating that freely available remote sensing data can be a powerful tool to quantify bat roadkill risk and assess its spatiotemporal dynamics.

Spatial Characteristics of Wildlife-Vehicle Collisions of Water Deer in Korea Expressway

“…Compared to past studies on WVC that have mainly addressed the status of WVCs, many recent studies have focused on analyzing the causes of WVCs and developing approaches to mitigate them. These studies include analyses of WVC occurrence depending on landscape variables [21][22][23], studies on the social costs of WVCs [11,17], and research verifying the effects of WVC mitigation strategies [24]. In the extensive literature on WVC occurrence, many studies on the correlation between WVC occurrence and landscape variables have been conducted worldwide [21,22], but such studies have been rarely conducted in Korea.…”

“…These studies include analyses of WVC occurrence depending on landscape variables [21][22][23], studies on the social costs of WVCs [11,17], and research verifying the effects of WVC mitigation strategies [24]. In the extensive literature on WVC occurrence, many studies on the correlation between WVC occurrence and landscape variables have been conducted worldwide [21,22], but such studies have been rarely conducted in Korea. Therefore, it is necessary to analyze the correlation between WVC occurrence and landscape by using Korea's WVC occurrence data to formulate a WVC reduction plan.…”

“…It is vital to identify these hotspots for reducing collision-related threats to wildlife [26,27]. Research on WVC hotspots involving wild animals has been widely used to prioritize locations for WVC reduction [22]. It is essential to identify spatial and temporal hotspots and analyze their effects on WVC occurrence to establish mitigation measures and thus avoid high WVC.…”

Bat Overpasses Help Bats to Cross Roads Safely by Increasing Their Flight Height

“…Until recently, despite the large pressure exerted by roads on animals, the effects of roads on insectivorous bats has been poorly documented (Berthin ussen and Altringham, 2012b;Kitzes and Merenlender, 2014;Abbott et al, 2015;Claireau et al, 2019c;Medinas et al, 2019Medinas et al, , 2021. Indeed, habitat connectivity in the landscape is a key element for bats (Hale et al, 2012;Frey-Ehrenbold et al, 2013;Pinaud et al, 2018;Laforge et al, 2019) but the fragmentation effect of road remains poorly evaluated.…”

Assessing bat-vehicle collision risks using acoustic 3D tracking

“…While most studies have focused on the effect of roads on larger mammals (Bartonička et al, 2018;Litvaitis and Tash, 2008), in recent years many researchers have grown increasingly concerned about the risk of collision between bats and vehicles (Fensome and Mathews, 2016). For example, a recent publication by Medinas et al (2021) found 509 bat casualties along a 51-km-long transect during a period of 3 years.…”