. >> among the 2 dozen scientists doing research at nachusa, is doctor holly jones, a conservation biologist at northern illinois university. with her team, she's trapping and tagging small mammals to assess the impact of the big bison. >> so its completely a restoration ecologists playground. i get so excited about this field site. let's see if someone is in there. there is! small mammals are food for aerial predators, things like hawks, things like owls and so it's really important to know how they're doing to be able to say how the prairie is doing as a whole. >> and that's because, if the small mammals are tasty enough to become good prey, they are feasting on a healthy environment of insects and plants. >> what are you seeing? >> since bison have been introduced we've had 13 lying ground squirrels which was very surprising. the line of evidence is pointing towards a shift in community composition. >> there are different plots of land that are being restored at different times from all the way back 20 years ago we can look at a plot of land like this that was restored four years ago and