available locations at four spatial scales for each of three guilds;

priority for species conservation

generally quicker and less expensive

reduce the viability of threatened populations

failed detection of approaching trains

Seasons of mortality risk were significantly higher for ungulates in mid to late winter, but were less pronounced for bears (slightly higher in late spring and early summer), and other carnivores (no strong seasonal effects). Wildlife mortality occurred more often during the day than night.

Temporal patterns of mortality differed among species (Figs. 3 and 4). Seasonally, ungulate mortality increased in winter (YearDaycosine = 0.583, SE = 0.063, z-value = 9.3) and spring

At the spatial scale of the study area, ungulates and bears had higher mortality where topographical complexity was lower, but topographical complexity increased mortality risk for carnivores at all scales. All guilds exhibited a tendency for greater mortality near roads, but this parameter occurred across spatial scales only for bears. An interaction suggested that the combined effects of train speed and proximity to water was most pronounced for other carnivores (Fig. 2). The logistic regression models with random points distributed along the railway throughout the study area did a moderate to poor job at differentiating mortality sites from random locations. Area under the ROC curve (AUC) was slightly higher for ungulates (AUC = 0.735) compared to bears (AUC = 0.634) and other carnivores (AUC = 0.683).

Mortality increased with percent of shrub cover

sidings, whereas risk for other carnivores increased with distance to sidings.

best predictor of mortality sites was maximum train speed, followed by proximity to water, amount of water within 90 m, and track curvature

BIC

We expected that that mortality risk would increase in seasons when deep snows, high water levels, and new precipitation made the railway more attractive for travel (winter) and when spilled grain and early emergent rail-side vegetation had higher nutritional quality and availability compared to broader food availability (winter and early spring) (daily precipitation; Table 2).

Bayesian information criterion

We hypothesized that the ability of an animal to perceive an approaching train would reduce strike risk such that mortality rates would increase with increasing track curvature, change in elevation, posted train speed, and canopy cover. We also hypothesized that features that channel animal movement onto the railway would increase risk of collisions, predicting mortality rates would increase with topographic complexity, the amount or proximity of water, proximity of roads, and canopy closure. We hypothesized that high forage quality in the vicinity of the railway would increase animal attraction, and hence the risk of strikes, predicting positive correlations with proximity to railway sidings (where trains travel slowly such that leaking grain accumulates39) and with higher shrub cover, which provides berry-producing forage for bears and browse for ungulates. Finally, we hypothesized that strikes would increase where animals spent more time because they had high security from people in the busy valley bottoms of these protected areas, predicting that mortality would increase with distance to roads, shrub density, and canopy cover.

logistic regression models

We included data from the following species for analysis: grizzly bears, black bears (Ursus americanus), wolves (Canis lupus), coyotes (Canis latrans), cougar (Puma concolor), lynx (Lynx canadensis), moose (Alces alces), elk (Cervus canadensis), white-tailed deer (Odocoileus virginianus), mule deer (O. hemionus), unspecified deer, and bighorn sheep (Ovis canadensis) (Table 1).

unit of replication

Elevational declines occur in both directions from the continental divide that separates Banff and Yoho National Parks and these lower elevation areas contain higher densities of many species, especially ungulates in the east end of Banff

Banff and Yoho National Parks

We expected that mortality risk would increase in (a) places where animals had difficulty perceiving trains, (b) where their movement paths were constrained by adjacent topography or water, (c) where forage opportunities increased, or (d) where the railway provided security from encounters with people

The objectives of this paper were to (a) identify the landscape factors and seasons that increase train-caused mortality for large mammals and (b) determine the similarity of these explanatory variables among guilds as a means to assess and prioritize the broader conservation value of potential mitigations.

wo factors limit the viability of expensive fencing and crossing structures in this context.

most cost-effective and ecologically beneficial mitigation while identifying the strengths, as well as limitations, of management actions dedicated to focal species

features such as drainages channel the movement of multiple species

vulnerable to vehicle collisions in predictable locations

site- or time-specific, vs. continuous and permanent.

high track curvature that are near water or attractive habitat.

highest in winter for ungulates and other carnivores, and in late spring for bears, respectively.

among guilds and spatial scales, with shrub cover, topographic complexity, and proximity to sidings and roads

ungulates

Mortality risk increased across multiple guilds and spatial scales with maximum train speed and higher track curvature, both suggesting problems with train detection, and in areas with high proximity to and amount of water, both suggesting limitations to animal movement

Banff and Yoho National Parks, Canada

mitigated

are

Railways