Mouse nest under porch

We live in a fairly new townhouse complex (Calgary). I discovered some small holes dug underneath the concrete porch, and when I stepped on the surrounding earth, it sank fairly easily, about three inches. I assume that there is a mouse nest underneath the porch. I did some light reading and will be buying some mouse traps to line the garden area. Will packing the area underneath the concrete porch with loam/dirt be enough to prevent a future infestation? Mike.

It is common for backfilled soil around a new structure to settle.  Rodents could easily burrow into this soil and packing it down will not make any difference.  If you have a rodent problem you should place traps in an animal and child proof bait station.  You could also call a local professional for help.