Tamiasciurus douglasii

Now includes Tamiasciurus mearnsi (Hope et al. 2016). American Society of Mammalogist (Koprowski et al. 2016) and IUCN (Cassola 2016, de Grammont and Cuarón 2018) still recognize T. mearnsi as distinct, however Koprowski et al. (2016) cite Arbogast et al. (2001), Hope et al. (2016) and Pecnerova and Martinkova (2012) in suggesting that T. mearnsi does not represent a distinct species.

Tamiasciurus mearnsi was regarded as a distinct species by Lindsay (1981), Hoffmann et al. (in Wilson and Reeder 1993), and Thorington and Hoffman (in Wilson and Reeder 2005). Earlier, Hall (1981) had suggested that T. douglasii and T. hudsonicus might be conspecific, but Lindsay (1982) concluded that apparent hybrids probably were examples of character convergence.

This species is widespread and common with no major threats in the US and Canada, the majority of the range. The Mexican population (formerly T. mearnsi) is listed as Endangered by IUCN due to a decline in both the extent and quality of its habitat, as well as in the number of mature individuals through competition with an introduced species.

Southwestern British Columbia south through coast ranges, Cascades, and Sierra Nevada to southern California, and Sierra San Pedro Martir, northern Baja California, Mexico.

This species is likely known from a large number of occurrences and has over two thousand observations on iNaturalist (iNaturalist 2020). There are less than 5 localities in Mexico (de Grammont and Cuarón 2018).

There are no major threats to this species in the US or Canada, though it may be locally threatened by deforestation and habitat fragmentation (Cassola 2016). In Mexico, this species habitat is threatened by timber removal, grazing, wildfire, and competition with introduced Sciurus carolinensis (since the 1940s). This species' biggest threat in Mexico is loss of biological diversity due to anthropogenic activities such as deforestation and restricted habitat (Ramos-Lara 2012) (de Grammont and Cuarón 2018).