I replaced a dried out tube a few weeks ago and checked it again to see a hole chewed in the bottom. To keep it shaded I had to hang it on a wire fence and an inch or less away from a tree.

First thought was duct tape (many layers) around the bottom or perhaps PVC to put over the end or entire tube. I don't think the PVC should interfere with the operation as long as the small holes in the top are clear.

Anyone had a similar situation and how did you solve?

Obviously this is outside of buying a pellet gun and thinning the squirrel population.

Probably a Persian rat.

They have always held a grudge against the Spartans.

Same thing happened on mine. I popped the top off of a beer can (leaving the solid rim on the edge). The tube slides right into it. I lined the rim with a little duct tape to make it fit tighter.

That's what she said protected.