I am checking with this walkthrough (scroll down until "BREEDER HOUSE").
I killed the two Rattkin Breeders in that house. As stated, this made the Rattkin Common are now hostile and attack me.
BUT, neither Madras nor Chief Gari award me any EXP. I forgot to talk to Madras, but when I got all the way back down the tree, and talked to Chief Gari, the first thing he said to me was "My guards tell me the rats are still in the tree! You haven't killed them yet" ...
I am sure that I search every house/room up there.
Are there any more that I missed. If so, where?
[Update] I just climbed the tee again and talked to Madras, who greeted me with "I thought you were going to kill the breeders?". So, I must have gotten the challenge, and no other walkthrough (I have since red a few) mentions any other breeders.
I am stumped, and will continue to search.