Rats don't live alone!!! They multiply like crazy. I am sure there is more than one rat. Keep a careful watch on the coop and run, Im afraid his friends will continue what he started. You need to block every hole you see. Keep the food out of the run because they won't stop coming if there is always a free meal. Keep the trap up and add others. Good luck I hate rats!!!
Poison is the best way if possible. I had rats over the winter but with two weeks of poisoning it took care of them. The first 4 days they were carrying off 5 to 7 blocks each night. They stopped taking them and I found some dead. I now keep blocks and change kinds every few weeks to make sure they don't become a problem again. Another good thing about keeping poison blocks out is that it takes care of mice as well, even though they don't bother me too much.
Just remmber if you use poision you poision everything else to animals can get into it kids can get into it pets can get into it , its possible depending on what you use that it can get into water or food sources. If you dont do what you can to rat prooff your property you can use all the poisons you want and well rats will breed like rats as someone said. It tends to be safer and less costly in the long run to prevent instead of try to kill off . Man kind has been trying for thousands of years with little luck.
Thanks for the info. I am going out there today and look to see if there is any sign of another out there. I think I may try some poision but realy dont want that around my chickens. I may just set the trap a few more times just to see what I may get before useing poision.
You have to be careful of where you put the poison but most exterminators will tell you that poison is the most affective way to get rid of rats. They carry it back to the colony and it will kill several of them.