Buy a tent, get some used hockey gear, camp out and take a stand. 
 
It is a free food smorgasbord to a wild animal, it is going to take some degree of effort to outwill them. 
 
What about covering the pond with steel square grid stucco mesh or chicken wire? 
		
	
		
		
		
		
		
	
		
		
	
	
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