we're going thru the SAME thing with Cheri - she is climbing trees to get HER squirrel - Wish I could tell you how to stop them but I have no idea - they know their teasing the yorkie kids too - they really are doing it on purpose -
MY squirrel Hangs on the Fence like he's sleeping waiting for the girls to come outside then RACES up and down the fence -
I just got this (terrible) pic the other day of him laying in wait

I REALLY believe this is what he was saying too