TRAIL WATCH
← Field guide
No. 032 · rodent · Risk: Moderate

Deer Mouse

Peromyscus maniculatus

Deer Mouse
In season · SeptemberSouthwestMidwest / PlainsMountain WestPacific WestAlaska
Field tell
Bicolored tail, white belly, large ears; common in cabins, woodpiles, and trail shelters.
Why it matters
Primary reservoir of hantavirus (Sin Nombre). Do not sweep dry mouse droppings in enclosed shelters.
Habitat
Rural buildings, seasonal cabins, rock piles, and campgrounds.
Season
Year-round; indoor encounters increase when weather turns cold.
HANTAVIRUS

If you find mouse droppings in a cabin or shelter

  1. Do not sweep or vacuum dry droppings — that can put virus into the air.
  2. Ventilate the space for at least 30 minutes. Leave while it airs out.
  3. Wet droppings and nests with a disinfectant (bleach solution), wait 5 minutes, then wipe with paper towels.
  4. Seek medical care promptly for fever, muscle aches, and shortness of breath after rodent exposure — hantavirus pulmonary syndrome is a medical emergency.

Not medical advice. Call 911 or Poison Control 1-800-222-1222.