Aplodontia rufa
Silhouette: Daderot · PhyloPic
In 3 days ~10% in a week ~30%
The mountain beaver (Aplodontia rufa) or sewellel is a North American rodent. It is the only living member of its genus, Aplodontia, and family, Aplodontiidae. It should not be confused with true North American and Eurasian beavers, to which it is not closely related; the mountain beaver is instead more closely related to squirrels. There are seven subspecies of mountain beaver, six of which are found in California and three of which are endemic to the state.
The name sewellel was recorded by Lewis and Clark who misunderstood the Chinook word [ʃʔulal] (which they annotated as "she-wal-lal"), the name for garments made from their skin; the Chinook themselves call it "ogwoolal" (pronounced [əɡʷulal]). "Mountain beaver" is a misnomer as the animal is not a true beaver nor restricted to mountains.
The name Aplodontia ("simple tooth") is in reference to the single large basin comprising the bulk of each cheek tooth. The specific epithet, rufa, means red or reddish. Most references use the spelling "Aplodontidae" for the family name. This has been deemed incorrect due to the technical rules of converting a genus name into a family name. The proper conversion of Aplodontia... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Olympic National Park | 🇺🇸 United States |
More parks will be added in future updates.
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Seattle | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Mountain Beaver sighting in Seattle on a given day, based on 30 verified sightings from GBIF citizen-science data. It is the 20th most-seen of the 25 mammals we can rate there. Over three days the chance rises to about 10%, and over a week to about 30%, if each day is a fresh chance.
May and August–September
In those months about 10% of wildlife watchers report a Mountain Beaver in Seattle on a given day, against under 5% in June–July and October–April, the lowest months. Those are among Seattle's driest months, with about 50 mm of rain a month against 190 mm in November.
Between noon and 3 pm
Across all the parks we cover, that three-hour window holds the most Mountain Beaver sightings with a recorded time, and about 7 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Only Seattle, in our data
Seattle is the only city on Wallace's Line with enough records to rate Mountain Beaver sightings: under 5% of wildlife watchers there report one on a given day.
Same order: Rodentia
The closest relatives of the Mountain Beaver that you can see in Seattle (order Rodentia, Rodents) are Eastern Gray Squirrel (about 40%), American Beaver (about 30%) and Douglas' Squirrel (about 10%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Mountain Beaver is recorded against all the mammals logged in Seattle (30 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
