Washington mammals

Black Rat in Washington

Rattus rattus

Introduced to Washington

Washington's Rattus rattus 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.

Live black rat climbing through branchesBlack rat moving through leaf litter and low vegetationLive black rat on open ground with long tail visibleLong-tailed black rat standing on a railingLive black rat in a tree near a building
Photo: Ryan Hodnett · CC BY-SA 4.0Live black rat climbing through branchesPhoto: Bernard DUPONT from FRANCE · CC BY-SA 2.0Black rat moving through leaf litter and low vegetationPhoto: Davidvraju · CC0Live black rat on open ground with long tail visiblePhoto: Alex O'Neal · CC BY-SA 2.0Long-tailed black rat standing on a railingPhoto: Sean Vanderluit · CC BY 4.0Live black rat in a tree near a building

Black Rat in Washington, by the numbers

Occasional in Washington 55th most recorded of 145 mammals logged in Washington

303 occurrence records
195 with iNaturalist photos
Jul 4, 2026 Last seen in Washington

Records from 2000–2026.

303 total records count every Washington occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 299 records with a full observation date.

When to look for the Black Rat in Washington

Most sightings fall in June to November.

299 Washington occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence.

Monthly Washington records (table)
MonthRecords
January29
February21
March15
April11
May18
June33
July33
August29
September33
October29
November32
December16

Monthly black rat occurrence records (iNaturalist and GBIF) in Washington, 2000–2026.

Seasonality

Year-round in Washington, with recorded sightings peaking in June–November, with a smaller rise in January–February.

Occurrence map

Where Black Rat has been recorded in Washington

300 records mapped · zoom and drag to explore

300 Washington records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
San Juan Islands National Monument 17
Whatcom Wildlife Area Complex 2
San Juan Island National Historical Park 1

Protected places with the most black rat 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 Washington

CountyRecords
King County 149
Whatcom County 38
Pierce County 25
Snohomish County 15
San Juan County 14
Jefferson County 11
Kitsap County 11
Thurston County 8
Grays Harbor County 4
Walla Walla County 4
Benton County 3
Island County 3
6 other counties 18

The complete county distribution, spread across 18 Washington counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Washington’s 2000–2026 dataset contains 303 black rat records. The feeds contribute 195 iNaturalist and 260 GBIF records, and their overlap is retained only once in the total. On the atlas scale, the species occupies position 52 of 126.

The monthly maximum occurs in September with 33 records; the minimum is 11 in April. The leading counted place is Olympic National Park (1 record). Those signals belong to reporting history and should not be treated as relative population size.

Occurrence data from iNaturalist and GBIF.

Live black rat climbing through branches
Full species profile Black Rat Rattus rattus Size 16–24 cm6.3–9.4 in Weight 75–230 g2.6–8.1 oz Lifespan 4 yr View the full profile

More mammals in Washington in the atlas

Data & sources

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

  • GBIFCC-BY 4.0occurrence records behind the range map, elevation, and record counts
  • iNaturalistCC0 / CC-BY / CC-BY-SAobservations, photos, and audio recordings
  • NatureServe ExplorerCC-BYthe state conservation rank
  • IUCN Red Listattributed factthe global conservation status
  • USGS NASpublic domainnative / introduced status
  • Natural Earthpublic domainthe relief basemap
  • USFSpublic domainnational-forest boundaries
  • USGS Protected Areas Databasepublic domainthe named parks, forests, and refuges behind "notable places to look"