Linking habitat composition, local population densities and traffic characteristics to spatial patterns of ungulate‐train collisions

Abstract

1. The total length of railways worldwide exceeds 1 million kilometres and recent railway development directly impacts wildlife because of animal-train collisions.Few studies, however, have analysed factors driving ungulate-train collisions.2. We analysed over 3,500 ungulate-train collisions including roe deer, red deer, wild boar, and moose collected in 2012-2015 in Poland. We compared train traffic characteristics (e.g. traffic intensity, speed, rail curvature), land-use and habitat characteristics (e.g. share of forests and build-up areas) and local ungulate population densities at collision sites and random sites distributed along the rail network. 3. Forest coverage generally increased, while urban areas decreased ungulate collision risk. Local density of ungulate species had a strong positive relation to the relative collision risk in all four ungulate species, but above certain densities, the risk levelled off for all four species. 4. Train speed and train traffic intensity were positively associated with elevated collision risk in all four species, but the latter in a nonlinear manner reached an asymptote at the level of c. 10 trains per day. Rail curvature also increased probability of collisions with roe deer and red deer and possibly also wild boar. 5. Mortality rate of ungulates on railways in Poland is estimated to be 0.13%-0.42% of annual hunting bags of studied species assuming that only one individual is killed at each occasion and ignoring undetected collisions. These values are expected to increase in the near future due to increasing train speed in Central European countries. 6. Synthesis and applications. Ungulate-train collisions spots are characterized by surrounding forest, rail curvature, high train speed, and a moderate to high train traffic intensity. To reduce collision risk in a cost-effective way, we suggest prioritization | 2631 Journal of Applied Ecology JASIŃSKA et Al.

Railway mortality for several mammal species increases with train speed, proximity to water, and track curvature

“…Track curvature was positively related to mortality at all spatial scales of analysis for bears and at the three smaller spatial scales of analysis for ungulates. Again, this effect is consistent with other studies of wildlife mortality on both roads 50,52 and railways 35,53 . Another set of researchers working in our study area hypothesized that curvature would increase collision risk primarily if it reduces the ability for wildlife to detect approaching trains via acoustic cues 54 .…”

“…The absence of this effect at smaller spatial scales may reflect the lesser variation in train speed over shorter distances. Several other studies of rail mortality also identified a positive effect of train speed 35,48,49 and vehicle speed is broadly associated with wildlife-vehicle collisions on roads 50 . A plausible explanation for the ubiquity of this relationship is that fast vehicles simply overwhelm the sensory capacity, and hence motor response, of animals 51 .…”

“…We did not include measures of human use, which are known to affect the distribution of wary carnivores 13 . Our use of shrub cover as a variable precluded use of the correlated (but weaker) variable of forest cover, which has sometimes been positively associated with rail mortality 35,63 and sometimes negatively 34 . Fourth, our guild-based unit of analysis overlooked species interactions, such as the avoidance of grizzly bears by black bears 75 .…”

Impact of Road Fencing on Ungulate–Vehicle Collisions and Hotspot Patterns

“…However, as of 2011, the numbers of both UVC and fenced road sections started to grow on roads characterized by lower speed and traffic intensity (Figure 4A). Similar to other countries [46,47] this UVC increase can be an effect of increasing wildlife populations in Lithuania [13].…”

Overabundant wild ungulate populations in Europe: management with consideration of socio‐ecological consequences

“…For example in Spain, there have been increases of 3600% and 300% in UVCs with wild boar and red deer respectively from 2006 to 2012 (Sáenz‐de‐Santa‐Maria & Tellería 2015), and in Sweden, there has been an increase of almost 600% in UVCs with wild boar from 2003 to 2012 (Savberger 2010 in Thurfjell et al 2015). UVCs also include train collisions, which are affected by ungulate density (Jasińska et al 2019) and are increasing in some countries (e.g. Poland, Czech Republic, Hungary), although few studies have been performed regarding this subject (but see Cserkész & Farkas 2013, Kušta et al 2014, Krauze‐Gryz et al 2017).…”