Rats and mice

Yes, it's that time of year.  If you live in (or near) the country, you know what I mean:  Mice are trying to find a nice, warm place to spend the winter, and they really prefer living in a house with people; a home where there is dog food just sitting there for the taking, and crumbs dropped here and there to snack on.  
I've strategically placed mouse poison around the house, making sure it's in places where Iris can't find it.  This is an ongoing war, but I always win each battle.  I know how to deal with mice.  
Rats, not so much.  I was pretty sure I saw a big rat out of the corner of my eye last week, and sister-in-law Rena confirmed my suspicions the next day.  She got a good look at a rat whose size, according to her, surpassed that of a German shepherd.  
So Cliff and I had a nice motorcycle ride Friday to look at used tractors that will be auctioned off Monday at Cook Tractor.  That man could look at tractors all day long.  I just enjoy the ride that takes us to see them.  
On the way home, we stopped at a farm store and bought some bar bait, which is rat poison in a solid block that you just toss under and behind things; it works much better for outside use than the small pelleted stuff I use in the house.  
The next day, any bar bait I had tossed around was gone.  Totally.  I guess the rats must have taken it to their burrows to feed their families.  Or maybe that German-shepherd-sized one ate it all at one sitting. 
Because there are unkept yards on either side of our property where these pests can thrive, I imagine we'll always have to watch for them, and watch I shall!  My house is not that far from the barn, and I would freak out if any of those nasty rodents made it into my home.  
I try not to think about the fact that one female rat can easily raise twenty babies in a year.  
*shudder*