The 18 mammal species below are known or suspected to be present, even if on an irregular basis, within the Report Area. Taxonomy and nomenclature follow NatureServe. Images, where available, are by the author.
Virginia Opossum (Didelphis virginiana) – Introduced
Seemed largely absent from the area until about a decade ago. Now occurs commonly throughout. Primarily nocturnal, but sometimes active during the day.
Broad-footed Mole (Scapanus latimanus)
Status difficult to ascertain because of its primarily subterranean habits. Most records are of deceased moles.
Yuma Myotis (Myotis yumanensis)
Given their primarily nocturnal nature and difficult identification, all bats are data deficient in the area. Mt. Washington is well within the known range of this species. In iNaturalist as a single non-confirmed sound record near the LA River.
Northern Hoary Bat (Lasiurus cinereus)
Given their primarily nocturnal nature and difficult identification, all bats are data deficient in the area. Mt. Washington is well within the known range of this species. Likely the most common bat in the area. In iNaturalist as two confirmed records of dead bats near the LA River. Observed and photographed in flight by the author along the LA River after sunrise in 2022.
Brazilian Free-tailed Bat (Tadarida brasiliensis)
Given their primarily nocturnal nature and difficult identification, all bats are data deficient in the area. Mt. Washington is well within the known range of this species. Single photographic record from the LA River in 2019.
Desert Cottontail (Sylvilagus audubonii)
Largely absent from the area until about ten years ago, the author believes the creation of Rio de Los Angeles State Park allowed for this species to return to the area. Numbers can fluctuate dramatically from year to year.
California Ground Squirrel (Otospermophilus beecheyi)
Formerly uncommon locally until the construction of Rio de Los Angeles State Park. This native ground squirrel is often considered a pest, with denser populations frequently exterminated because of the risk of plague from their fleas.
Eastern Fox Squirrel (Sciurus niger) – Introduced
Common throughout in areas with trees. This species is introduced to Southern California and has displaced the native Western Gray Squirrel, which no longer occurs locally.
Botta’s Pocket Gopher (Thomomys bottae)
Common throughout except, perhaps, at Rio de Los Angeles. Loose, granular dirt piles are indicative of the species’ presence.
Black Rat (Rattus rattus) – Introduced
Brown Rat (Rattus norvegicus) – Introduced
House Mouse (Mus musculus) – Introduced
Coyote (Canis latrans)
Common throughout, and freely travels at night dispersing on major roads that are dense with traffic during the day. Most easily observed early in the morning shortly after sunrise.
Gray Fox (Urocyon cinereoargenteus)
There is one scat record for this species in the Mt. Washington area in iNaturalist. All other evidence is anecdotal. If it occurs in the area at all, it occurs very rarely.
Raccoon (Procyon lotor)
Common throughout. Numbers tend to increase over a period of years followed by a crash due to disease outbreak. Primarily nocturnal, but sometimes active during the day.
Striped Skunk (Mephitis mephitis)
Common throughout. Numbers tend to increase over a period of years followed by a crash due to disease outbreak. Primarily nocturnal.
Bobcat (Lynx rufus)
The first local Bobcat that the author is aware of was found by the author in Elyria Canyon Park in 2015. What was presumably the same Bobcat was observed and photographed by many in the area for several months after. iNaturalist shows records with photo documentation from Glassell Park in 2019 and Mt. Washington in 2023.
Mule Deer (Odocoileus hemionus)
Has been observed several times by the author in Elyria Canyon Park over the years. Deer likely wandered into the area over night and got trapped as the sun rose. The longest known to have stayed was a buck present for at least a week around 2005 or 2006.