Rats are creatures of habit. They like to stick to the same routine day in and day out. So, when they find a place that suits their needs, they’re likely to stay put.
Bravo to Ellie Gruber for making this public. The HHK brook bordered our former property and while we did not have people dumping directly there, we always had garbage and debris floating down the brook from storm drains. I would collect plastic bottles, styrofoam cups and plastic lids, straws, tennis balls, plastic bags and a variety of other garbage on a daily basis. Just too much litter all over and little or no respect for our few remaining wild spaces. Members of the throw away, convenience society are also very lazy and selfish.