The house mouse is Maine’s most familiar mammal and one of its least documented. It arrived with European settlers centuries ago and lives as a companion to human habitation, which means the 65 records in the occurrence databases understate reality by an enormous margin. People photograph warblers and bobcats; almost nobody logs the mouse in the pantry.
What’s interesting in the record is where the reports do come from. Oxford and Waldo counties, both rural and heavily wooded, hold 45 of the 65 between them, far ahead of Cumberland County, where most Mainers live. That inversion of the population map suggests the records aren’t tracking mice so much as they’re tracking field biologists, small-mammal trapping projects, and attentive rural naturalists. Aroostook County adds eight more from the farm country up north.
Reports peak in September, with a smaller rise in March, times when mice press into buildings ahead of winter and then stir again in spring. NatureServe doesn’t assign the species a state rank, since it’s introduced and needs no conservation attention. The honest summary: the house mouse is everywhere people are in Maine, and the record map mostly shows where someone bothered to write it down.
Full species profile
