One of the most interesting additions to a survival pack I have seen is a common or garden spring rat trap...The guy who showed it me was ex Rhodesian Light Infantry soldier & reckoned it had fed him often while operating in the bush...Depending on how where he set it and what he baited it with, he caught all manner of small critters...He also prefered to use his fishing kit for catching birds...very cruel indeed, but understandable in some of the situations he was in....