Report Summary

 

• Brown and grizzly bears are killed by train strikes in Europe and North America every year. In the contiguous USA alone, 55 grizzly bears have been killed by trains since 1980, accounting for 9% of total known or probable deaths in the Cabinet-Yaak (CYE) and Northern Continental Divide (NCDE) Ecosystems since 1997. In the similar physical environment of Banff National Park (NP), Canada—but with roughly twice the railway traffic as in the USA—train strikes currently account for nearly ¼ of all grizzly bear deaths.

 

• Grain that either leaked or spilled from hopper cars has been and continues to be a major attractant for grizzly bears along the Canadian Pacific and Burlington Northern-Santa Fe (BNSF) Railways. Feeding by bears on grain along railways has been well-documented in Canada, although there is no comparable data from the USA to determine whether purported mitigation measures have reduced consumption of grain by bears along the BNSF Railway.

 

• Grizzly bears are also likely attracted to railways by carrion from train strikes and by increased abundance of certain vegetal foods during spring and fall attributable to a modified proximal physical environment. Increased abundance of horsetail, buffaloberry, and certain weedy forbs such as dandelion has been documented along the Canadian Pacific Railway in Banff NP.

 

• Seasonal patterns of habitat selection and mortality from train strikes support the conclusion that significant numbers of grizzly bears are attracted to railway environments during spring and fall. Train-caused deaths exhibit pronounced spikes during May and September-October along the BNSF Railway in the NCDE; similar monthly patterns occur in Eastern Europe and along the Canadian Pacific and Canadian National Railways. The fall increase in train strikes in both Canada and the USA is consistent with bears continuing to seek out grain spilled from hopper cars transporting fall harvests west from the Great Plains.

 

• Heavy vehicle traffic on highways paralleling railways displaces grizzly and brown bears spatially as well as temporally—albeit contingent on the richness of nearby natural habitats. Such patterns have been documented along both US Highway 2 in the NCDE and along the Trans-Canada Highway (TCH) in Banff NP.

 

• Highway crossings by grizzly and brown bears are nil when traffic is greater than roughly 100 vehicles/hour, although this level of traffic is restricted largely to day-time hours on Highway 2 and the TCH. As a result, highway crossings are displaced to night-time and crepuscular hours, coincident with low light levels and times when bears naturally feed most heavily.

 

• In contrast to highways, bears tend to not avoid railways, as such, perhaps because of much lower levels of individuated traffic on railways compared to highways, as well as the presence of anthropogenic attractants.

 

• Bears avoiding heavy day-time traffic on nearby highways; peak railway traffic during night-time and crepuscular hours; and the attractiveness of railway environments combine to produce a potentially lethal situation for grizzly bears active near or trying to cross major transportation corridors such as US Highway 2 and the BNSF Railway.

 

• The abbreviation of daytime crossing opportunities that predictably comes with increasing vehicular traffic, when combined with increased levels of night-time and crepuscular train traffic, will almost certainly increase the lethality of the Highway 2/BNSF corridor in the NCDE and CYE—as well as the Highway 200/Montana Rail-Link corridor southwest of the Cabinet Mountains.

 

• The TCH/Canadian Pacific Railway corridor foreshadows the consequences of increased vehicular and train traffic along the Highway 2/BNSF corridor. The physical environments of both corridors are quite similar, both transect protected grizzly bear populations, and the TCH/Canadian Pacific corridor is transected by levels of both vehicular and train traffic that will, in the future, likely typify the Highway 2/BNSF corridor. Train strikes promise to be a major cause of bear deaths, comprising an even larger fraction of the total in both the NCDE and CYE.

 

• Regardless of whether or not grizzly bears are attracted to railways by spilled grain or rail-side vegetation, bears die from being struck by trains of all sorts. Self-evidently, grizzly bears do not preferentially seek out locomotives pulling one assortment of cars versus another. A coal train can be as lethal to a bear as a freight or grain train.

 

• The Highway 2/BNSF corridor bounds and transects the main source area for the NCDE grizzly bear population centered on Glacier National Park and the Middle Fork of the Flathead River. Several researchers have flagged incipient or full-blown fracturing along this corridor as a potential threat to long-term viability of the NCDE population. Fracturing is almost certain to be accentuated by increased vehicular and train traffic along the corridor, thereby posing a significant threat to this grizzly bear population.