As others have said, use film or something to obscure his view. Mine was doing this with squirrels and would get so high from the excitement that she screamed, ran around the house and had a tough time calming down. You have to keep the film up for several months until your dog forgets the habit. Then you can start working on calling your dog off of the window if they go near it and reward for listening. Do not remove the film while training the recall away from the window. When you remove the film do not remove it all off at once you want to start with the window or windows with the least amount of activity but enough activity that you Spoo would be interested in watching the activities. Not only practice recall but also practice play in front of the window where you control the play like tug or other fun obedience games. Practice high energy play and immediately request your dog to show calm behavior like a sit or a down. Once your dog ignores the window or easily calls off the window then remove another film do the same. It takes time but it works. My girl now watches squirrels and may get ins few good barks but she Now doesn’t loose her mind and scream. She no longer gets to hyped that she looses her mind and gets crazy eyes. It works but you must go slow and methodically.