Here we had rats in the coop, and three nice pullets beheaded at night, in addition to eggs eaten.  Redo your security, use bait stations, wear gloves, and get rid of them!!!
In our case, rats moved into a wall cavity easily chewing through particle board to get there. Also there was a small gap at a corner of our hardware cloth skirt around the coop, together with a crack in the concrete foundation.  it doesn't take much to have rodent problems!  And if a rat can enter through it's tunnel, so can a weasel, who will kill everyone at once!
And I agree about bait choices;  read the labels!  And keep any other critters from reaching the bait.  Most dying rodents will return to their burrows and die there, so are lower risk for being found by other animals.  Not zero risk, and any sick or dead rodents found need to go into a bag in the garbage.
Mary