Deer Mice

Deer Mouse Facts

• Color: Grayish to reddish brown on the back, with white fur on the belly and feet and a tail that is darker on top
• Size: Roughly 3 to 4 inches from nose to rump, plus a tail of about 2 to 4 inches, with big eyes and ears for its size

Deer Mouse Behavior

They look harmless, but deer mice are the main carrier of Sin Nombre virus, the hantavirus behind most cases of hantavirus pulmonary syndrome in the United States. The illness often starts like the flu, with fever, muscle aches, headache and exhaustion.

Deer mice in Florida: what you are likely seeing

The true deer mouse ranges across much of North America but is generally not found in Florida. When Floridians see a mouse with a crisp two-toned coat, white belly and white feet, it is usually one of its native relatives:

• Cotton mouse: brown above and white below, common statewide in hardwood hammocks, swamps and wooded lots, and the one most likely to wander into rural homes, cabins and sheds.
• Oldfield mouse: smaller and paler, living in sandy fields and scrub. The coastal beach mice are forms of this species, and several of them are federally protected.
• Florida mouse: found only in Florida, in dry sandy uplands, and known for its large ears and eyes.

Telling these apart from a house mouse is fairly easy. House mice are a fairly even grayish-brown with a slightly lighter belly, smaller eyes and ears, and a nearly hairless, single-colored tail. Deer mouse relatives have big dark eyes, large ears, bright white undersides and tails that are dark on top and pale below.

All of them are active mainly at night and eat seeds, nuts, acorns, berries and insects, often stashing food for later. They nest in burrows, hollow logs, stumps and brush piles, and in sheds and outbuildings when they can get in. North Florida homeowners tend to notice them most in the cooler months. See deer mice infestations for signs indoors.