Bigfoot?

[hellbilly]

http://www.youtube.com/watch?v=FzELdzjXVQk

[Jack]

I always have to wonder - why didn't they walk closer to it and get it to move?  Oh yeah, it wouldn't have been all mysterious then 

[Derf]

Looks like a bear butt to me. The leaves hanging down over the upper left flank give it the look of a head. But most likely, it's a bear sleeping in the tree (note the other big branch behind the one its butt is on, thereby making a nice sleeping platform. It probably got chased up the tree by a house cat.

http://www.youtube.com/watch?v=gi7tN2rjQcc