Just now appeared on the page of my book, ran round for a minute, then hopped off.
I have 2 cats who have been bringing little mice into the house and also bring a lot of voles and moles to the door.
I also have new chicks but I doubt they are the source.
Looks similar to these which have been associated with Deer Mice by Pierre and Tom.

Any information if these will bite humans or breed in the house.