Delaware mammals

House Mouse in Delaware

Mus musculus

Introduced to Delaware

Delaware's Mus musculus records are of an introduced species; it does not occur here as a wild native population.

IUCN Red List status

  1. LC
  2. NT
  3. VU
  4. EN
  5. CR
  6. EW
  7. EX

LC – Least Concern

Widespread and abundant; not at risk.

House mouse in dry plant litterHouse mouse on concrete near green plantsHouse mouse beside a curbHouse mouse moving through dry stemsHouse mouse partly hidden in leaf litter
Photo: hatwise · CC BY 4.0House mouse in dry plant litterPhoto: dandri · CC0House mouse on concrete near green plantsPhoto: trisairatops · CC BY 4.0House mouse beside a curbPhoto: hatwise · CC BY 4.0House mouse moving through dry stemsPhoto: hatwise · CC BY 4.0House mouse partly hidden in leaf litter

House Mouse in Delaware, by the numbers

Occasional in Delaware 27th most recorded of 62 mammals logged in Delaware

19 occurrence records
19 with iNaturalist photos
May 9, 2026 Last seen in Delaware

Records from 2000–2026.

When to look for the House Mouse in Delaware

Most sightings fall in December to January.

19 Delaware occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence. Based on a small number of dated records; the seasonal pattern may not be representative.

Monthly Delaware records (table)
MonthRecords
January3
February1
March1
April2
May1
June0
July0
August2
September3
October0
November1
December5

Monthly house mouse occurrence records (iNaturalist and GBIF) in Delaware, 2000–2026.

Seasonality

Year-round in Delaware, with recorded sightings peaking in December–January, with a smaller rise in September.

Occurrence map

Where House Mouse has been recorded in Delaware

19 records mapped · zoom and drag to explore

19 Delaware records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Ted Harvey Wildlife Area 1
Trap Pond State Park 1

Protected places with the most house mouse sightings, from the USGS Protected Areas Database plus named mountain ranges, good spots to look, not a full breakdown, so they don't sum to the total.

Where it's recorded in Delaware

CountyRecords
New Castle County 9
Sussex County 8
Kent County 2

The complete county distribution, spread across 3 Delaware counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

House Mice are introduced in Delaware and usually live in or near buildings, barns, storage areas, and other disturbed settings. Observations from Cape Henlopen, Trap Pond, or refuge property may originate around visitor facilities rather than the surrounding natural community.

They occur year-round; the small record set has isolated peaks rather than a reliable field season. Indoors, secure food and seal small openings; outdoors, avoid disturbing monitoring equipment placed by land managers.

Occurrence data from iNaturalist and GBIF.

House Mouse in other states

House mouse in dry plant litter
Full species profile House Mouse Mus musculus Size 5–10 cm2–3.9 in Weight 12–30 g0.4–1.1 oz Lifespan Up to 4 yr View the full profile

More mammals in Delaware in the atlas

Data & sources

The data and visualizations on this page draw on these open sources: