Preventing Rodents (rats) from Returning to existing burrows

mice

When dealing with rodent (specifically Rats) infestation and or prevention. What is the best way to deal with new rats finding the existing burrows (even after the entrances have been sealed).

IOW – After evicting several rats and about a week past since any activity – an existing hole was re-opened. Assuming these arent the same rats, but new ones (hence the time gap) — how/why do they find the areas of interest, and what can be done to mitigate this?

Original Question – not a direct Home Improvement Question

CITY/ALLEYS/RATS — I get it, they exist

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?

Best Answer

Rats leave behind a scent as they enter and exit burrows. When you "evicted" those rats, that scent was still there and at some point, another rat came across it and thought "Hey, someone else was digging here, there must be something good there!" and started digging again. That's how you always end up with rats re-digging tunnels or chewing through a blockage in a hole, they appear to be pre-programmed to investigate anything that another rat has done and given that they tend to be prey for so many types of predators, its a good survival strategy for the species.

The thing that I found has worked is to get fox / coyote urine crystals and sprinkle them around the area after you evict them. That overrides their curiosity factor with a danger factor. You can order it on-line from numerous sources. Just be forewarned; your dogs will be VERY VERY interested in that smell too. This by the way also works to keep skunks away from going under porches and decks.

I am currently experimenting with pouring liquid ammonia around their excavations to see if that has a similar effect, based on the fact that urine eventually breaks down into that at some point. So far so good actually, but right now is the peak of their invasion season as they begin looking for places to raise their babies, so it remains to be seen if it really stops the onslaught.