Northern Bog Lemming

Synaptomys borealis

NENot Evaluated
Illustration: northern bog lemmings (as Arvicola borealis) from John Woodhouse Audubon's 1845 Northern Meadow-Mouse plateIllustration: detail of three northern bog lemmings from Audubon's 1845 Northern Meadow-Mouse plate
Photo: John Woodhouse Audubon (1845 plate); rawpixel (digitization) · CC BY 2.0Illustration: northern bog lemmings (as Arvicola borealis) from John Woodhouse Audubon's 1845 Northern Meadow-Mouse platePhoto: John Woodhouse Audubon (1845 plate); rawpixel (digitization) · CC BY 2.0Illustration: detail of three northern bog lemmings from Audubon's 1845 Northern Meadow-Mouse plate

The northern bog lemming is one of the hardest small mammals in Alaska to actually see, spending nearly its entire life tunneling through moss, sedge, and dense low vegetation rather than crossing open ground. It shares its genus with the southern bog lemming, distinguished mainly by grooved upper front teeth that only show up under close inspection. Records below concentrate in a short Alaska summer window and reach beyond the state too, into isolated mountain populations as far south as Washington and Montana.

Range through the year

Northern Bog Lemming range map: where northern bog lemmings live in the US

Northern bog lemmings are established in 6 US states: Alaska, Idaho, Maine, Minnesota, Montana, and Washington. They are most often recorded in Alaska (503 records) and Montana (5). Occasional records also come from New Hampshire.

Established range6 established states · 510 records
AlabamaArizonaArkansasCaliforniaColoradoConnecticutDelawareDistrict of ColumbiaFloridaGeorgiaIdaho · view state pageIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontana · 5 records · view state pageNebraskaNevadaNew Hampshire · occasional recordsNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashington · 2 records · view state pageWest VirginiaWisconsinWyomingAlaska · 503 records · view state pageAKHawaiiHIPuerto RicoPR
Occurrence data by state and month
Northern Bog Lemming: occurrence records by US state and month (510 records in total)
StateJanFebMarAprMayJunJulAugSepOctNovDecYear
Alaska···2·2017928913···503
Montana······14····5
Washington······1·1···2

Based on 510 georeferenced US records. Shading is observation density (where people record sightings), not true abundance. Established range follows NatureServe state ranks; occasional records fall outside it. Alaska, Hawaii & Puerto Rico shown as insets.

Explore by state

Northern bog lemmings state by state

Occurrence records, conservation status, and the places it turns up, state by state. Open a state for detail, or visit its full page.

  • AlaskaNativeOccasional503 records

    Notable placesGates of the Arctic National Park · Yukon-Charley Rivers National Preserve · Wrangell-St. Elias National Park · State Tentatively Approved (tad)

    Countiesrecorded in 13

    Year-round in Alaska, with recorded sightings peaking in July–August.

    Full Alaska page →All Alaska mammals →
  • MontanaNativeRare5 records

    Notable placesLolo National Forest

    Countiesrecorded in 4

    Sparse observation record in Montana; presence confirmed but timing of activity not well documented.

    Full Montana page →All Montana mammals →
  • WashingtonNativeRare2 records

    Notable placesWashington State Department of Natural Resources (WADNR) State Resource Management Area

    Countiesrecorded in 2

    Sparse observation record in Washington; presence confirmed but timing of activity not well documented.

    Full Washington page →All Washington mammals →
  • IdahoNativeRare

    No dated Idaho records from 2000 to 2026.

    Full Idaho page →All Idaho mammals →

IUCN Red List status

NE – Not Evaluated

Not yet assessed against IUCN Red List criteria.

SizeNorthern Bog Lemming beside a 1.8 m adult, drawn to scale
Created by potrace 1.16, written by Peter Selinger 2001-2019 Created by potrace 1.16, written by Peter Selinger 2001-2019
Body length
13–13 cm5 in–5 in
Weight
21–21 g0.7–0.7 oz

Silhouettes drawn to scale against a 1.8 m5 ft 11 in adult.

Observation peakJanuary0 recordsBased on a small number of dated records; the seasonal pattern may not be representative.

Seasonality from research-grade observation dates across the US (0 records, all years). Reflects when the species is recorded, not a guarantee of presence.

Best encounter

Where and when to see a Northern Bog Lemming

Your best chance: Alaska, in January.

Where
AlaskaAK
When
January

Life history

The Northern Bog Lemming (21 g0.7 oz) is an omnivore that bears about 4.3 young per litter.

Reproduction

Litter size
4.3youngaverage
Litters / year
2.5litters

Diet composition

Omnivore

By foraging composition: 80% plant material, 20% invertebrates.

  • Plant material80%
  • Invertebrates20%

Most active around the clock.

Typical values for the species, not local measurements.

Commonly confused with

Animals people sometimes mistake for the northern bog lemming, and how to tell them apart.

A lemming built for tunnels, not open ground

Most of what a northern bog lemming does happens out of sight, in shallow burrows and surface runways cut through moss, sedge, and matted grass. It rarely crosses open ground the way a vole or a squirrel might. That habit makes it one of the least-photographed small mammals in its range despite being reasonably widespread. Up close, the clearest way to separate it from a true vole is a set of narrow, deep grooves running down its upper front teeth. That’s a genus-level feature shared with its southern relative, and it isn’t visible without a close look.

Alaska’s population, and a few surprising outposts elsewhere

Nearly every documented record of the northern bog lemming in the US comes from Alaska, where it turns up across wetlands, tundra, grassland, and boreal forest. But the species doesn’t stop there. Small, disjunct populations persist much farther south, in isolated pockets of the northern Rockies and Cascades in states like Montana and Washington. Those are holdovers from a colder climate that once stretched much further south than it does now, a reminder that a species’ current range can be shaped as much by past ice ages as by present conditions.

An omnivore in name and diet

Unlike many of the strictly plant-eating voles and lemmings sharing its habitat, the northern bog lemming rounds out a mostly plant-based diet with a real share of invertebrates and other small prey, whatever a shallow tunnel through wet ground turns up. That broader diet may help it get by in habitats too wet or too disturbed for a pickier neighbor to manage.

Active around the clock, hunted by nearly everything bigger

Rather than keeping strictly to day or night, the species stays active in bursts across both, adjusting its schedule to weather, season, and how much daylight Alaska happens to have at the time. That flexibility doesn’t make it any safer. Most medium and larger mammals that eat smaller prey will take a bog lemming given the chance, and its main defense is simply staying hidden in the tunnels and runways it rarely leaves.

Northern Bog Lemming range questions

Which US states have northern bog lemmings?

Northern bog lemmings are established in 6 US states: Alaska, Idaho, Maine, Minnesota, Montana, and Washington. Occasional records also come from New Hampshire.

Do northern bog lemmings live in all 50 states?

No. Northern bog lemmings are established in 6 of the 50 states.

Where are northern bog lemmings most common in the US?

Record counts follow where people look as well as where animals live, so they are not a population estimate. Northern bog lemmings are most often recorded in Alaska, with 99% of 510 US records, followed by Montana and Washington.

Are there northern bog lemmings in my state?

Northern bog lemmings are established in 6 US states. Outforia's state pages for northern bog lemmings, including Alaska, Montana, and Washington, cover local records, conservation status, and the places they turn up.

Sources

  1. GBIF – Synaptomys borealis
  2. Wikipedia – Northern bog lemming
  3. iNaturalist – Northern Bog Lemming

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
  • PhyloPicCC0 / CC-BY per itemthe to-scale silhouettesNina Skinner (Cricetidae) · Andrew A. Farke (human silhouette, CC-BY 3.0)
  • AnAge (HAGR)CC-BY 3.0longevity, maturity, and gestation figures
  • IUCN Red Listattributed factthe global conservation status
  • NatureServe ExplorerCC-BYthe state conservation rank
  • Amniote Life-History DatabaseCC0 · public domainreproduction figures
  • EltonTraitsCC0 · public domaindiet and foraging-activity data