I went to retrieve my trail cam pics today ( Saturday-6/13/09) and came across this picture of this certain critter. I myself think it's a groundhog. After a couple of my hunting buddies saw the picture they had different oppinions. One friend think's it a beaver, one friend thinks it's a fisher and yet another friend seems to think it's a very large musk rat.
What do you guys think it is?

http://www.flickr.com/photos/92426379@N00/3621849633/