Here is my best list I can come up with on the fly:
-Loss of habitat
-Deterioration of remaining habitat (invasive weeds, cheat grasses, etc)
-Increased amount of roads
-Expansion of existing roads
-Greatly increased vehicle traffic
-Migration corridors being cut off
If you could figure out how to mitigate 5 of the 6 of these, I believe you'd see a huge benefit. We aren't tearing out roads or killing people off, bulldozing their homes, and turning them back into forest or sage brush, but can we mitigate these factors in some way? I don't know, that is not what I'm paid to figure out.