It is not necessary to go all the way to Yellowstone to see rodents. When we returned from Yellowstone we took a day trip up to Crex Meadows, in Wisconsin, on June 1st. At Crex we saw some mammals too.
For example chipmunks can be found all over, as we found out by photographing them in Yellowstone then at Crex. We even have a chipmunk living in our yard. From time to time Misty and I will sit at the window and watch as the chipmunk fills his cheeks with maple seeds.
We also spotted some thirteen-lined ground squirrels. These ground squirrels are native to prairies and grasslands in the central US. They are very cute, especially when they stand up to survey their domain, usually consisting of 2 to 3 acres of grassland. They are also the mascot of the University of Minnesota.
We also spotted a white-tail deer. We spotted a few deer in and around Yellowstone but they were all mule deer. Someone did report seeing a white tail while we were there but they are much more rare in Yellowstone. In Minnesota you can see white tail deer all over.
The most exciting mammal that we saw at Crex on that trip was a pair of river otters. They crossed the road a little ways in front of us and by the time we got down to where they had entered the water they had swam a ways away into the rising sun. This made getting any descent pics impossible.