Sadly, we've had to use poison to control them. Poison was our last option, but it worked well and fast. First we tried the bait bricks, and the rats carried them away and I didn't find any dead rats, but I noticed a small dip in the population.
Next we bought the pelleted rat feed in the tray you lay out. We put the whole box out, 4 trays total and lo and behold all the rats bit the dust. Big ones, small ones, males and females. I think the pellets work best because one rat can't drag it off and gaurd it, therefore more rats eat from the trays. AND because the tray stays where you put it, you know when the poison is gone and you can stop worrying about the chickens or other animals getting it.
Since we set the pelleted poison out, about a week ago, I've picked up 2 HUGE rats and 4-6 large adults. I'm sure there are more, but these are just the ones that died out in the open.