Opposite end of decking there's a brief commotion, and *two* rats shoot out from under the decking. (Which does make me wonder wtf the neighbours cats are up to when they prowl our garden ????)
From experience, trapping is hit and miss, and I know rats tend to avoid anywhere humans have been - making trap laying less effective.
Not a massive fan of poison - quite aside from the possibility of it not working anyway, the chances of a dead rat where you can't get to it isn't appealing.
I did have a vague idea about flooding the under-decking space with carbon monoxide ... never heard of it being used this way before, but as it's outdoors, and CO is heavier than air (and so should pool under the decking) ... If I then remove one of the decking planks, I can access the entire under-run to remove any rodent corpses ?
Or am I being too cavalier about risks of CO - despite it being outdoors and below the door level to the house ?
Can you buys CO canisters ? Or would a hardcore DIY project be to make my own CO source ?