Worse, chicken food sometimes contains Vitamin K; the antidote to rat poison.
I find insomnia, windless evenings, a good thermal sight , and a German PCP air rifle makes the problem more interesting than annoying.
Blocking most of the holes up and putting dry ice (from our lads food business) in all but one hole almost guarantees a stream of conveniently placed targets.
We've stopped poisoning them because weakened rats are easy targets for our tomcats. They tended to vomit the remains by our bedside or on my (not her) pillow.
Getting my own back as it were