Cut other trees down. Chain a dog to the pear tree doing guard duty. Possibly put up an owl decoy. Assume shooting them is out of the question.

Terminate with extreme prejudice. Shoot, trap & terminate, big bucket-o-death, whatever it takes.
Search this site (especially the Fruit & Orchards forum) for 'squirrel' - you'll find multiple lengthy threads.

This post was edited by lucky_p on Wed, Aug 28, 13 at 12:12