I would bet that if there are presently more, they have figured out that 'you' are a bad thing, something to be avoided. I can recall as a kid trying to catch a rat or several which lived in a building we housed poultry in. Somehow they managed to avoid my initial attempts at catching and later poisoning them. When I finally did manage to catch the old matriarch/patriarch in a blind set some time later, one of its legs had scarring from having previously being pinched along its length. One wouldn't think a rodent would have the intelligence of a canine, but they sure seem to learn well when their life is on the line.
