Our miniature schnauzer and her daughter (mini schnauzer/pit bull) would kill anything they could catch.
They were both highly skilled in the art of catching birds out of the air.
One time, someone broke into our house and released several hundred (if not over 1,000) feeder mice and rats.
We came home and it looked like it rained headless rats and mice outside.
Another time, we left them at a friend's house while we went out of town. He was also babysitting an African Gray parrot for someone else.
My mom told him to keep them away from the cage, because they would try to kill the bird. He assured us that there's no way they could get in the cage.
Well, before we even left his house, they busted through the bottom of the cage to try and kill it.
They also almost killed themselves trying to get a ground squirrel once.
It was mid summer (so well over 100 degrees outside), and I came home from school one day and noticed they were gone. I looked EVERYWHERE for them. When I went out back, I called for them again, and I could hear heavy panting from underneath our concrete patio.
They dug themselves a good 8 feet underneath. Shelbye (the mix) had gone in first with Schatzi (mini schnauzer) right behind her. Schatzi tried turning around and got stuck, and heaven only knows how long they were down there. We called the fire department, the humane society, police - NOBODY would come and help. Our neighbor was a mechanic, so I ran over there to see if he could help us. He rigged up something real quick - a PVC pipe with a hook on the end so we could reach down and get them out by their collars. They were overheated and dehydrated, but they ended up being okay.
So my vote is with schnauzers or any other sort of terrier....
(And mind you, we didn't train them to kill anything - they just did it).
Ozzy - Chocolate Pom
-Fastest 2012/2013 U-FLI Pomeranian
"In a perfect world, every dog would have a home and every home would have a dog."