We have an area in the back yard, that had an impressive rat burrow under a concrete slab. After 2 months of smoke and traps, we got 8 rats evicted. We've closed the holes, and for over week there has been no movement around the known entrances. Just this AM, there was digging at one of the most frequented entrances. Im trying to understand how rats work. Do they migrate to other feeding areas/burrows through the week, and are now coming back to this one? Or is this a new potential potential occupant for that burrow - but how do they know it's there?