I've been told that chickens go into a trance like state at night, and rats will walk right up to them and chew off body parts...daytime would be another story.
Its not that they go into a trance so much, but the result is the same.
chickens have no night vision and because of that, they dont move around in the dark.
Rats will definatly kill your chicks.
If rats can get in yor coop, so can a weasel. A weasel will kill all chickens regardless of their age or size.
Make your coop secure so nothing gets in at night.
The only chicken fatality in my “neighborhood “ that I know of due to a predator was because of a rat. So, yeah. The come for the crumble and stay for the chicken.
Welcome! As others already mentioned, get the hardware cloth over every opening right away! Also, bait stations set up in safe places to kill all the rats, before they get your birds.
Mary
I use rat bait stations. I had an infestation in one of my coops. Usually the rats will dig tunnels and when they die most go into their tunnels. Once in awhile you may find a dead rat which I dispose of, but for the numbers I have had in the past I have found very few dead ones. I put the bait stations where my birds and other critters can't get to them. This is what I have had the most success with. If poison is not the way you want to go then use the snap traps. I did not have as good of luck with the Tom Cat rat bait that came with the bait station.