There's a vole in my kitchen

Oh dear dear me. We have a mouse problem. A mouse in the house. Well, actually a vole problem. Four little voles have been discovered roaming loose about the house. I don't know if it's the same one each time or not. We've been catching it and letting it outside. Three have been discovered touring the living room, and one ran past my foot whilst I was cleaning the kitchen. The little thing thought it was a pet (maybe it had befriended the gerbils and wanted to join their community?) This little thing just ran around me, and when I cornered it, it just sat looking at me. The only voles I've ever seen before were usually terrified of humans. Anyway, this morning Steve heard scratching on top of the kitchen cupboards and found a little vole munching on a king size dairy milk chocolate bar, which had been hidden up there from the kids! There is a whole next to the extractor fan, in the wall, so Steve has blocked that up, hoping it's how they have been getting in. I also found mousey doo-doo's in the airing cupboard! Oh yuck yuck. I hoovered it out, spent two hours cleaning through all the duvets and towels and doing a well needed reorganising session. A little poison might be called for, but I hate to think of the little things suffering.