Colorado mammals

Pacific Marten in Colorado

Martes caurina

Native to Colorado S4 Apparently Secure in Colorado

Not listed as nonindigenous in Colorado by USGS NAS; native to its Colorado range.

IUCN Red List status

NE – Not Evaluated

Not yet assessed against IUCN Red List criteria.

Pacific Marten in Colorado, by the numbers

Common in Colorado 51st most recorded of 154 mammals logged in Colorado

388 occurrence records
382 with iNaturalist photos
Jul 5, 2026 Last seen in Colorado

Records from 2000–2026.

388 total records count every Colorado occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 380 records with a full observation date.

When to look for the Pacific Marten in Colorado

Most sightings fall in June to September.

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

Monthly Colorado records (table)
MonthRecords
January23
February22
March14
April12
May14
June42
July59
August65
September66
October26
November15
December22

Monthly pacific marten occurrence records (iNaturalist and GBIF) in Colorado, 2000–2026.

Seasonality

Year-round in Colorado, with recorded sightings peaking in June–September.

Occurrence map

Where Pacific Marten has been recorded in Colorado

300 records mapped · zoom and drag to explore

300 Colorado records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Rocky Mountain National Park 72
Indian Peaks Wilderness 20
White River National Forest 16
Routt National Forest 13
Eagles Nest Wilderness 7
Maroon Bells-Snowmass Wilderness 4
Steamboat Lake 2
Gunnison National Forest 2

Protected places with the most pacific marten 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 Colorado

CountyRecords
Larimer County 65
Grand County 49
Summit County 38
Boulder County 34
Routt County 25
Gunnison County 20
Pitkin County 17
Eagle County 14
Lake County 14
San Miguel County 12
Mineral County 11
Mesa County 10
16 other counties 79

The complete county distribution, spread across 28 Colorado counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

The Pacific marten is a but seldom-seen carnivore of Colorado’s highest forests. Open occurrence databases hold 388 records for it, 382 of them iNaturalist observations, a modest count for an animal that lives where few people go and slips away fast when they do.

A specialist of the subalpine spruce and fir

The marten belongs to cold, dense, high-elevation conifer forest, the Engelmann spruce and subalpine fir just below treeline. Its records trace that habitat across the mountains, concentrated in Larimer, Grand, and Summit counties, with White River National Forest and Rocky Mountain National Park among the dependable places to find it. Continuous canopy over a deep, snowy understory littered with downed logs is what it needs; fragmented or low forest holds almost none.

Hunting all winter

The marten does not hibernate. This cat-sized weasel stays on the hunt through the deep cold, tunneling under the snowpack after voles and red squirrels and denning in hollow logs and rock cavities. The summer rise in records is simply when hikers reach the high country, not any sign of dormancy. A marten’s tracks lace the subalpine snow in January just as its paws cross the talus in July.

Status in Colorado

Native and apparently secure, ranked S4 by NatureServe. As a snow-forest predator it is sensitive to logging and to a warming climate that thins the deep, lasting snowpack it hunts within, which keeps it a species worth watching even where it remains reasonably common.

More mammals in Colorado 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"