Question
I have a maple tree in my back yard - urban setting. Last year we found thin strips of bark on the ground surrounding the tree. Major branches in the upper portion of the tree were stripped bare. We thought of squirrels, but someone else mentioned lightning.  The top died section, so I cut the top out and tarred the cuts.  
Recently the problem has returned - more branches being stripped.  Another maple is starting to show this problem on the bottom branches.  Is this sound like squirrels? or what else?

Answer
It does sound like squirrels. Squirrel repellant are an option in some circumstances but are not effective in deterring bark-stripping. Capsaicin, the active ingredient in hot sauce, is a registered repellent and polybutene is a sticky tactile repellent. I think I would try putting hot sauce on the bark--it will not hurt the tree and should repel the squirrels. Live-trapping is an option if the problems come from a few persistent squirrels. Permits maybe required to do this in your area check with your local Game and Parks Commission or a local animal control office. Trapped squirrels should be released in a vacant habitat
wooded area that doesn't have many other squirrels. Resident squirrels are very territorial and transplants may not survive.


Here is a  web site that describes animal damage to trees including squirrels.
http://www.extension.org/pages/Barkstripping