Although this species is common, and currently has no special conservation status, people should remain mindful that their activities could greatly reduce the western pipistrelle population, if steps are not taken to ensure that bat habitat is protected.
Like all bats, western pipstrelles are most vulnerable at their roost sites and therefore protection of these roost sites is the focus of most management. Since reopening abandoned or inactive mines can negatively affect bat colonies, it has been recommended that multi-seasonal surveys be conducted prior to allowing any renewed mining. These same issues should be considered when a mine is recommended for permanent closure. If bats are roosting in a mine scheduled for closure, installation of a bat gate is preferred method for preventing unauthorized human access while allowing the bats passage.
Human disturbance can be extremely detrimental to bat colonies, especially to non-volant young and hibernating adults, depending on the season and severity of the disturbance. Mines that are in close proximity to roads, towns, hiking trails or camp grounds are more susceptible to disturbance then those in remote areas with difficult access.
There is a need for greater assurance that roosts will remain undisturbed and that future (potential) roost sites will be left when managing for bats in pinyon-juniper habitat. Ideally, management should aim to sustain adequate food, water, and roost sites in close proximity to one another (Klingel, 2000).
Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. While there are currently no reports of Parastrellus hesperus mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern