This month's Natural Mystery comes from Hidden Falls Regional Park, on the east bank of the Mississippi River, just upstream from the Hwy 5 bridge. These tracks were part of a winding trail I found on March 7 of this year. The trail wound about 15 meters across an exposed area of sand between the paved trail and the river bank. The question is "Who?"

An ideal answer will identify the track maker as specifically as possible, explain how you arrived at your answer, and explain how you eliminated other candidates.