Myotis evotis

This taxonomic concept follows The American Society of Mammalogists (ASM) and Bats of the World (Simmon and Cirranello 2025) and retains M. keenii and M. evotis as distinct species. This status was re-affirmed by the Global Bat Taxonomy Working Group (Upham et al. 2022). There remains debate over the status of keenii (see Nagorsen and Brigham 1993, Van Zyll de Jong and Nagorsen 1994, Nagorsen 2002, Lung et al. 2013, Lausen et al. 2019, Morales et al. 2021, and Lausen et al. 2021). According to ASM, "The burden of proof is on overturning the species-level status of Myotis keenii, which has been recognized consistently by taxonomic authorities since 1979 and is thus the prevailing usage in need of refutation."

Population genetic analyses by Lausen et al. (2019) revealed four well-defined groups (species): M. septentrionalis, M. thysanodes, M. lucifugus, and a single group comprising M. keenii and M. evotis. They conclude that M. keenii does not qualify as a genetic or biological species and should be synonymized with M. evotis. Morales et al. (2021) re-examined the data of Lausen et al. (2019) and disputed this conclusion, however, the rebuttal by Lausen et al. (2021), confirms the data were accurate.

M. milleri in Baja California was treated as a distinct species in Wilson and Reeder (1993) but was included in M. evotis by Simmons (in Wilson and Reeder 2005).

Widespread distribution in western North America; many occurrences in wide range of habitats; occurs regularly in low numbers across range; uses wide range of often plentiful roost sites; trend uncertain but probably relatively stable or slowly declining; no known major threats, but range, habitats, and threats during winter are poorly known.

Range includes western North America, from central British Columbia (and probably southern Yukon), southwestern Northwest Territories, and southern Saskatchewan south along the Pacific Coast to Baja California, east through Montana and Idaho to the western Dakotas, and from Nevada, Utah, Wyoming and Colorado to New Mexico and Arizona (Manning and Jones 1989, Adams 2003, Lausen 2006, Reid 2006, Slough pers. comm.). Elevational range extends from near sea level along the Pacific Coast to around 2,900 meters in Utah and Wyoming (Manning and Jones 1989, Adams 2003).

The number of distinct occurrences has not been determined using standardized/meaningful criteria, but the species is represented by a large number of collection/observation sites and locations (as defined by IUCN). As evidence of this, Verts and Carraway (1998) mapped more than 100 collection sites in Oregon, Hoffmeister (1986) mapped 52 localities in Arizona, and Nagorsen and Brigham (1993) mapped approximately 49 collection sites in British Columbia.

Overall, no major threats are known. Locally, these bats may be affected to some degree by a multitude of factors, including the closure of abandoned (unsurveyed) mines, recreational caving, some forest management practices, and activities (such as highway construction, water impoundments, blasting of cliffs for avalanche control) that impact cliff faces or rock outcrops (Bogan et al. 2005). Broadcast application of pesticides to combat insect pests potentially has a detrimental impact on bat food resources or on the bats themselves, but population impacts are uncertain. Toxic impoundments associated with resource extraction are a potential source of bat mortality or contamination (Buseck and Keinath 2004).

Forest management practices that result in reduced availability of roost sites in snags and trees with loose bark may have a negative effect on these bats. Roosts under exfoliating bark may be relatively short-lived resources (Vonhof and Barclay 1996, New Mexico Department of Game and Fish 1997). However, stumps (Vonhof and Barclay 1997, Waldien et al. 2000) and rock crevices (if available) (Snider et al. 2013) may provide numerous suitable alternate roosts.

A single Myotis evotis was found dead with white-nose syndrome in Washington State (Washington Department of Fish and WIldlife 2019). At present, this threat is considered Low, but could increase if the disease spreads more widely in the west.

Increased incidence of wildfires might negatively affect bat food resources or degrade local environmental conditions, but substantial populations of M. evotis can persist even in extensively burned areas where suitable rock-crevice roosts are available (Snider et al. 2013).

This species is subject to mortality from turbines at wind energy facilities. Arnett and Baerwald (2013) estimated that approximately 3,730-7,330 individuals were killed by turbines in the United States and Canada during the period 2000-2011. Given the ongoing increase in turbine installation, this mortality may increase significantly during the foreseeable future. Although the current impact of turbine-associated mortality on the overall M. evotis population is probably relatively small, the reproductive rate for this species is low, and the ability of regional populations to sustain current and future levels of impact is uncertain.

The impact of potential threats associated with pollution and climate change are unknown.