My dog and squirrels in our backyard

My wirehaired dachshund, Otto, has become very focused on getting all
of the squirrels in our backyard. He has figured out how to grab a branch
on the smaller trees and shake them out. I am trying to break him of this
because it is not good for a tracking dog to rely on his sight but we had
to video it the other night. We did not get video of the squirrel in the tree
but that is what he is doing, trying to shake it out.
http://www.youtube.com/watch?v=XyQV_JPxubk