My money is on the Bison. these human who do nothing but provide analysis and spin, and spin, and
spin ~ ~ are sooooo out of touch w/nature.... i find this very fascinating esp. since, there have
been couple "SMALL" earthquakes in Yellowstone over last couple weeks..
Bison just do not take to the roads, after spending hundreds & hundreds of years of grassland.
http://www.grindtv.com/outdoor/nature/post/bison-running-on-road-fuels-speculation-that-yellowstone-volcano-will-erupt/