Guide

Look closerMammals

Mice in birdhouses and old bird nests in winter

November to March

From late fall, white-footed mice move into empty birdhouses and old songbird nests, and family groups stay there through the winter. They stuff a box with soft bedding, or build a roof of twigs and other material over an old bird nest, and they often store seeds close by.

Why this time of year

Fall is when these mice store food near their nests, and families share one nest all winter. They don't hibernate, so from late fall to early spring some empty nest boxes have a mouse family sleeping inside during the day.

How to notice it

  1. On a daytime walk after leaf drop, look into bare shrubs and hedges for old cup-shaped bird nests. A nest with a domed top of grass, leaves or twigs, where it used to be open, may have been roofed over by a mouse.
  2. Look at the entrance hole of an empty birdhouse without opening it. Fluffy plant down, shredded bark or moss filling the hole can mean a mouse family is sleeping inside.
  3. Leave it closed and keep your hands out. The mice sleep there by day, and some boxes hold roosting birds in winter.
  4. If an adult cleans the box out in early spring, before birds start nesting, wear gloves and a mask, wet the old nest with a bleach-and-water mix, wait 5 minutes, then lift it out. Never sweep or brush it out dry.

Try this with kids: Look at the birdhouse hole, but don't touch it. Can you see fluffy stuffing that tells you a mouse might be asleep inside?

Safety

  • Don't handle mouse nests, droppings or the contents of a box with bare hands. Mouse urine and droppings can carry disease, including hantavirus, which you can catch by breathing in contaminated dust.
  • When cleaning out a box, wear rubber or plastic gloves and a mask, and wet the nest with 1 part household bleach to 9 parts water (or a disinfectant). Let it soak 5 minutes before lifting it out. Don't sweep, brush or vacuum it dry. Wash your hands afterward.
  • Kids should only look and leave the cleaning to an adult.

Sources

  • icwdm.orgICWDM: white-footed mice may use abandoned bird or squirrel nests and add a protective roof enclosing a bird's nest; family groups nest together through winter; store food near nest sites particularly in fall.
  • northernwoodlands.orgNorthern Woodlands (Susan Shea): white-footed mice nest in old bird and squirrel nests and in birdhouses; line nests with milkweed fluff, shredded bark, hair, feathers.
  • pressherald.comMaine Audubon naturalist: mice frequently use nest boxes in winter and cache seeds; recommends cleaning in March.
  • news.maryland.govMaryland DNR: mice may take up residence in bird boxes late fall through winter; remove before spring songbird season; gloves and dust mask.
  • delawarenaturesociety.orgDelaware Nature Society: about 10% of their nest boxes occupied by white-footed or deer mice in winter; fluffy nests, sleep by day.
  • bostonglobe.comBoston Globe quoting Tom French (retired MassWildlife): mice sometimes nest in birdhouses; away from the city the white-footed mouse takes over; deer mouse more in western MA.
  • cdc.govCDC: gloves; 1 part bleach to 9 parts water; soak 5 minutes; don't vacuum or sweep nesting materials.
  • boston.govBoston Public Health: wear mask and gloves; do not sweep or vacuum nests; no locally acquired case in Boston.

Checked against these sources on October 16, 2026.

In the guide for November, December, January, February, March

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