Guys, looked around and didn´t really find a heading that fit so..
Here goes.

I use the PCP´s for rat control. For various reasons we´ve got infested at the shop of mine.
As of this writing tally is up to 63.

I just recently did the jump to night vision, and in fact have set up all 4 of the PCP´s that way. One Yukon, one generic Asian one that uses a screeen, then an ATN Aries and finally a Pard NV008LRF.
That said, got that covered.

At the shop we at first shot many. Reaching 50 was rather easy, after that though it seems they have learned and gotten "gun shy" for lack of better words - why i reach out to you guys as i presume many of you are way more experienced than me on the subject.

I´ve tried to try and get a grasp on their behavior but.. no dice. They can get REAL scarce for a while, then all of a sudden - like once a week to ten days - they´re friggin everywhere.

These days i rarely spend nights at the shop but for various reasons me and an old friend of mine were at the shop last tuesday, and this was one of those days "they´re everywhere".
We had tasks to cater to so i just got to shoot one but peeking out the door to take a P or just walking over to fetch something from the car.. That night i easily saw 30-40 different ones.

Then the night after, about stone dead. Nothing. Not to be found.

When we go after them i normally put bait out. Old buns, pasta and the likes. Seems the more the eadibles smell the more rats - in short.

Trying to understand what runs these creatures though, i´ve tried making some sense out of their behavior.. nope. It´s like it´s all driven by pure chance. What gives?

At that "range" of ours (two spots to be sure of backstop and what have you) there´s an ever so slight background lighting. It´s like they´ve learned that even walking out into that very sparse lighting = death.
True enough, we do shoot them.. i mean. Hello. That´s the whole point, but it seems they´ve taken to that walking into the light CAN be bad and as stated this is anything but "super trooper" floodlight. More like 5 watts a bulb doing its thing, to hand you an idea at least.

We shoot them, we trap them (as in rat traps) but lately as stated.. and i´m trying to make some sort of sense out of what drives them.
Being wild animals i appreciate that they´re oppurtunists.. why logic to me tells they should go after anything that´s easy to stuff into their mouths.
In short i´ve taken them to be very primal animals. Kind of sex, hunger and sleep and that´s it.

We´ve also got mice at the shop, but them don´t really bother me. What i´ve learned though is that when they mice are not to be seen then normally the rats are around and vice versa.

Right now it´s winter up here. Being that time of year we´ve got fairly high temps and no snow at the moment. A month back is was 10 below zero and about 2 feet of the stuff.
That rats "burrow".. sure. On that we´ve got three clear holes in the ground right next to the actual building and these seem to stretch into/under the shop itself.
Then on the backside of the building it seems they´ve nested in the actual wall at one place. In turn there´s a couple of storages out on the lot and they´ve dug burrows there as well, two of them.

When it´s warmer we do NOT see this "once a week let´s go ballistic" while now during winter..

So.
You guys more knowledgeable on the subject than me, any ideas to spare?