Identity
Unique IDELEMENT_GLOBAL.2.638468
Element CodeAMACC01160
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicendemic to a single nation
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderChiroptera
FamilyVespertilionidae
GenusMyotis
SynonymsMyotis lucifugus occultusHollister, 1909
Other Common NamesArizona myotis (EN) Un Murciélago (ES)
Concept ReferencePiaggio, A. J., E. W. Valdez, M. A. Bogan, and G. S. Spicer. 2002. Systematics of Myotis occultus (Chiroptera: Vespertilionidae) inferred from sequences of two mitochondrial genes. Journal of Mammalogy 83:386-395.
Taxonomic CommentsThe bats in the Myotis lucifugus-M. occultus-M. fortidens complex have long been of debatable taxonomic status (Findley and Jones 1967). Myotis occultus was formerly included in M. lucifugus (Jones et al. 1992; Koopman, in Wilson and Reeder 1993), but now regarded as a distinct species. Allozyme data suggested that the two are conspecific (Valdez et al. 1999), but mitochondrial DNA and morphological evidence suggest that M. occultus is a specifically distinct, monophyletic lineage (Piaggio et al. 2002).
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2015-04-03
Change Date2015-04-03
Edition Date2015-04-03
Edition AuthorsHammerson, G.
Threat ImpactMedium - low
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Rank ReasonsModerately large range in the American Southwest and northern and central Mexico; many roost sites in snags, also uses buildings and bridges; presumed large population size; vulnerable to various forms of habitat loss and degradation, especially those that affect roosts; better information is needed on current abundance, trend, and threats; some cave-hibernating popuations may be vulnerable to declines from rapidly spreading white-nose syndrome.
Range Extent CommentsThe range encompasses northern and central Mexico, southeastern California, Arizona (Hoffmeister 1986, Arizona Game and Fish Department 2003), New Mexico (except perhaps extreme northeast; Frey 2004), southern Colorado, and perhaps southern Utah and western Texas (Piaggio et al. 2002; Valdez, pers. comm.). In Arizona, this bat is distributed predominantly in the highlands and upper stream reaches (Piaggio et al. 2002). In New Mexico, it is known from low-elevation riparian areas in the Rio Grande Valley and montane highlands. In California, it occurs only along the Colorado River lowlands and in the adjacent desert mountain ranges. The range meets that of M. lucifugus in central Colorado; that species occupies the northern third of the state (Valdez, pers. comm.). The only record from Texas is an unusual, perhaps intermediate specimen collected in 1893 near Fort Hancock in Hudspeth County; it is doubtful that a resident population exists in Texas (Piaggio et al. 2002, Schmidly 2004, Ammerman et al. 2012). Range limits in Mexico are uncertain; the species has been recorded from several localities in Chihuahua and a disjunct site near Texcoco in the Distrito Federal (Piaggio et al. 2002; Valdez, pers. comm.). In Arizona, this bat is most common at elevations of 1,830-2,806 meters, but it also occurs much lower along rivers in desert regions (Arizona Game and Fish Department 2003).
Occurrences CommentsThe number of distinct occurrences has not been determined using standardized criteria, but the species is represented by a fairly large number of collection/observation sites and locations (as defined by IUCN).
Threat Impact CommentsWithout citing specific examples or sources, Schmidly (2004) and Ammerman et al. (2012) reported that this species has declined sharply in much of its historical range in California as a result of pesticide use, control measures in nursery colonies, and disturbance at hibernation sites. However, the species historically occurred in California only along the lower Colorado River, and the species recently has been found there in riparian restoration sites (Calvert and Neiswenter 2012).
Cave/mine-roosting populations are vulnerable to disturbance (e.g., human intrusions) and to roosting habitat loss/degradation from mine closures or renewed mining.
Tree-roosting populations (e.g., Rabe et al. 1998) are vulnerable to factors that reduce the availability of roost sites (e.g., forest management practices that reduce the availability of snags, illegal firewood harvest, increased incidence of forest fires).
This species often is associated with large bodies of water that are unlikely to be greatly affected by water management.
Livestock grazing may potentially degrade bat foraging habitat by reducing prey availability, but the actual impact of grazing on populations of this species is uncertain.
Currently, this species is not known to incur significant mortality from turbines at wind energy facilities (Arnett and Baerwald 2013).
As of early 2015, this species was not known to be affected by white-nose syndrome, However, given its close (possibly conspecific) relationship with M. lucifugus (millions of which have been killed by WNS), certain cave/mine-hibernating populations of occultus may be regarded as potentially vulnerable to this rapidly spreading disease.