Y2Y recently contributed funds to continue the monitoring of wildlife underpasses along US Hwy 93 on the Flathead Indian Reservation in Montana. The monitoring is especially focused on grizzly bears, and it is conducted by the Confederated Salish & Kootenai Tribes (CSKT) and the Western Transportation Institute at Montana State University (WTI-MSU). It is important to know which of the existing crossing structures are used by grizzly bears, especially by sows with cubs. The preliminary data suggest that while some grizzly bears do use the existing underpasses, sows with cubs barely use them (Adams et al. 2023). Currently, the vast majority of the sows with cubs cross the highway at grade where they are at risk from being hit by vehicles. More wildlife fences and wildlife crossing structures are needed, and grizzly bears, especially sows with cubs, need very large underpasses or overpasses to safely cross to the other side of the road (Adams et al. 2023). Currently, the Montana Department of Transportation (MDT) is increasing the length of the fenced road section and connecting the fences to existing underpasses. This will likely reduce the number of roadkilled grizzly bears and other large mammal species. However, unless more suitable crossing structures are provided, it may also result in a greater barrier for grizzly bears, especially for sows with cubs.

Adams, P.J., M.P. Huijser & S.C. Getty. 2023. An assessment of existing and potential future mitigation measures related to grizzly bears along US Highway 93, Flathead Indian Reservation, Montana, USA. Confederated Salish and Kootenai Tribes, Pablo, Montana, USA.

Image: wildlife underpass in the process of being connected to a wildlife fence.