I agree with Redfeathers,  dont be too hard on yourself,  these things happen. 
They could have been smothered if others crowded into the nest box on top of them. Piling is often a cause of younger chicks demise but it can still happen to older birds if they are trapped.
Im really sorry.
Chel
	
		
			
		
		
	
				
			They could have been smothered if others crowded into the nest box on top of them. Piling is often a cause of younger chicks demise but it can still happen to older birds if they are trapped.
Im really sorry.
Chel
 
	 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
			
		
		
		
	
	
			
		 
 
		 
 
		 
 
		

 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		