Hello, I recently discovered we have this problem too. Tried baited snap traps and glue boards to no avail. Finally decided to pony up the cash and have a pro deal with it bc I live in quasi-suburbia (a little town in the middle of farm country). So, out came the Orkin Man last Friday, he suggested using the snap traps strategically placed along our fences, OR, he suggested I gas them with car exhaust while they are asleep during the day. Poison was not recommended bc of where we live and that we have outdoor pets who might get secondary poisoning if the rats move the bait.
Sooooo...I took our portable generator and set it up close to the burrow exit, then blocked the other two exits really well. Then I put a long 1.5" diameter hose that we use for cleaning our pond down the burrow as far as it would go, and then blocked up the rest of the exit by filling the dirt in and weighting it with stones.
I then started up the generator, and held the hose to the exhaust for about 15 minutes to make sure plenty of carbon monoxide got down there, and voila....no more rat activity since Friday. No new burrows, no damage to my coop, no stolen eggs.
I left the hose in place so any rat that wanted out had to crawl through it and then meet a trash can full of snap traps at his exit, but there has been no activity in the can at all. So I am assuming they are dead in the burrow. Just to make sure, we are leaving the hose in place til tomorrow, and then going to flood out the burrow.
If you have a big infestation, this may not work for you, but it seems to have worked for us so far.
Best of luck!
P.s. it also is supposed to work if you use car exhaust