I occasionally have mice escape in my mouse room or even get wild mice in there sometimes. The problem is there is no lack of food in the mouse room. I have bags of lab blocks, spilled grain, what ever even when everything is cleaned up there is still plenty of food to feed a stray mouse.
What is not readily avaliable is water. Except for the water in the automatic dripers there is no water in the room. At the feed store I buy a mouse poison that is mixed with water and set out in a small bowl. I have found it works better than anything else I've tried.
-----
Wade's Weptiles & Wodents