If they put wildlife crossings up in Montana the custom grill guard industry would collapse and that would obviously be unacceptable.
But seriously, there's evidence that bears, mountain lions and ungulates (moose/deer/elk) will learn to use bridges/tunnels.
I haven't had luck finding the article I read that had tons of pictures, but here's something relevant:
http://www.montana.edu/news/12062/ms...hway-crossings