Idionycteris phyllotis is found in the mountainous regions of the southwestern United States through central Mexico.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range encompasses the southwestern United States and part of Mexico, from southern Utah and southern Nevada south through Arizona (northwestern, central, southeastern; Hoffmeister 1986) and New Mexico (Mogollon Plateau and western Soccoro County in the San Mateo and Magdalena mountains; Frey 2004) to Distrito Federal and Michoacan in southern central Mexico (Simmons, in Wilson and Reeder 2005), including the Sierra Madre Occidental, Sierra Madre Oriental, and Sierra Volcanica Transversal. The range closely approaches California and Colorado, but as of 2005 no records were available for those states. The winter range is not known. The elevational range extends from 403 to 3,225 meters, with most records at 1,100-2,500 meters.

Subspecies hualapaiensis: southern Nevada, southern Utah, and northern Arizona (Mohave County and Coconino County north of the Grand Canyon); subspecies phyllotis: remainder of range (Tumlison 1993).

The defining characters of Idionycteris phyllotis, also known as Allen's Big-Eared Bat, are its large ears (34 to 43 mm) which possess lappets projecting from the base of the ears and extending over the forehead. Idionycteris phyllotis has a total length of 103 to 118mm, a tail length of 44 to 55mm, and a forearm length of 42 to 49 mm. The wing span of I. phyllotis ranges from 302 to 344mm. Dorsal and ventral pelage is long (10mm) and basally black with yellowish gray tips. A patch of white hair occurs at the base of the ears. Females are generally about 5% larger in head and body length, however, there is no difference in forearm length.

Range mass: 8 to 16 g.

Length: 12 cm

Weight: 13 grams

No other big-eared bat has lappets projecting from the ears and extending over the forehead (Hoffmeister 1986).

• Terrestrial

Idionycteris phyllotis primarily dwells in caves in mountainous pine and oak forests. The availability of water holes is a significant factor in habitat selection due to their high rate of evaporative water loss. Nearly all capture sites have been in the vicinity of rocks, such as cliffs or large boulders, their most probable roosting sites.

Terrestrial Biomes: forest ; scrub forest ; mountains

Comments: Habitat is primarily mountainous wooded areas (e.g., ponderosa pine, pinyon-juniper, Mexican woodland, oak brush) but also includes riparian (e.g., cottonwood) woodland; habitat ranges from Mohave desert scrub of low desert ranges to white fir forest (Hoffmeister 1986). Typically this bat is found near rocks: cliffs, boulders, lava flows, etc., and it is frequently netted along streams or over ponds. Maternity colonies of 30 to 150 individuals have been found in mine shafts, boulder piles, sandstone crevices, lava beds, and beneath the loose bark of large ponderosa pine snags (Bat Conservation International, Western Bat Working Group, Czaplewski 1983, Rabe et al. 1998, Adams 2003).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Seasonal movements are not well known (Czaplewski 1983). Summer resident in New Mexico (Frey 2004). Individuals may move from higher elevation summer ranges to low elevation winter habitats (OFarrell, unpublished data, cited by Western Bat Working Group).

An August telemetry study of 12 post-lactating females from a mine in the Black Mountains (Arizona) demonstrated high roost fidelity; bats traveled between 70-100 kilometers roundtrip nightly to forage in the next mountain range to the east, despite the presence of many abandoned mines in the foraging area (Brown and Berry 2004).

Idionycteris phyllotis is an insectivorous bat which feeds mostly by gleaning moths and stationary insects from surfaces.

Comments: Insectivorous. Feeds on soft-bodied insects, primarily moths, but also beetles, roaches and flying ants. Most food probably gleaned from vegetation or captured in flight.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 300

Comments: This species is represented by several dozen occurrences or subpopulations in the United States. Occurrence information is not available for the bulk of the range in Mexico.

10,000 to >1,000,000 individuals

Comments: Total adult population size is unknown but presumably exceeds 10,000. Up to 100 individuals per roost have been observed in six roosts in the Coconino National Forest, Arizona (Mammal Diversity Review Notes 1996).

Corynorhinus townsendii and Myotis thysanodes associate with I. PYLLOTIS in maternity roosts. Males probably roost solitarily while females form maternity colonies.

Comments: Emerges to forage late in evening; most often taken in nets after 9 p.m. (Hoffmeister 1986).

Females form maternity colonies during the summer months, from June to late July, where they give birth to and raise their young. Maternity colonies consist of an average of 30 females. Males live separately from the females during this time. Females give birth to a single young.

Range number of offspring: 1 to 1.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

In New Mexico, Arizona, and Durango pregnant females bearing a single embryo have been collected in June. Lactating females have been found from the second week of June to the first week of August (Czaplewski 1983).

Roost disturbance is the greatest threat to Idionycteris phyllotis. Mining activities have caused the relocation or extermination of several bat roosts. Reproduction is shown to decrease after relocation, threatening the survival of the roost. Deforestation removes the feeding environment for the bats, as well as that of their insect prey.

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 Idionycteris phyllotis mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.

US Federal List: threatened

CITES: no special status

IUCN Red List of Threatened Species: least concern

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Spotty range from central Mexico to southern Nevada and Utah; apparently fewer than 70 occurrences in the United States; status in Mexico is poorly known, but this bat probably is more numerous there than in the United States; roost sites are vulnerable to abandonment as a result of human activity, and they may be lost through incompatible forest management practices; protected at several locations in the United States.

United States

Rounded National Status Rank: N3 - Vulnerable

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Recently, extent of occurrence, area of occupancy, number of subpopulations, and population size apparently have declined but probably at a rate of less than 10% over 10 years or three generations.

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Population trends are not definitely known, but global extent of occurrence, area of occupancy, number of subpopulations, and population size probably have not declined substantially compared to the historical situation. Barbour and Davis (1969) and Hoffmeister (1986) pointed to the paucity of pre-1955 records for Arizona and discussed the possibility that this species has only recently expanded its range to Arizona, Nevada, Utah, and New Mexico. Hoffmeister (1986) found no factor (e.g., habitat change) that might account for this possible change. Population trends are unknown in Utah and Nevada (George Oliver and Carrie Carreno, pers. comm., 1998). Possibly stable in Arizona (Sabra Schwartz, pers. comm., 1998).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Threats include recreational entry into occupied caves/mines, active mining in occupied tunnels, vandalism or closure of abandoned mines used as maternity roosts, and timber management practices that reduce the availability of large pine snags for roosting. The Western Bat Working Group categorized the threat as "High" throughout the Rocky Mountain region (Adams 2003). The Arizona and Nevada natural heritage programs considered the degree of threat to be moderate (Sabra Schwartz and Carrie Carreno, pers. comm., 1998). Lack of adequate information for Mexican populations prevents range-wide assessment of the scope of threat.

An important mine roost was destroyed by relocation of a nearby highway (Western Bat Working Group 1998). Maternity colonies are easily disturbed, often resulting in abandonment (Arizona Game and Fish Department 1997). Limited data suggest that this bat may abandon mines that have been gated to prevent recreational entry, even if the gates are permeable to other bat species (Western Bat Working Group).

Biological Research Needs: Most aspects of the ecology of this species need further study.

Global Protection: Several (4-12) occurrences appropriately protected and managed

Comments: At least four protected occurrences exist in Utah: Canyonlands National Park, Capitol Reef National Park, Glen Canyon National Recreation Area, and Natural Bridges National Monument (George Oliver, pers. comm., 1998), and at least a few additional protected occurrences are in Arizona (e.g., Grand Canyon National Park) and New Mexico. Occurrences in several national forests and in national wildlife refuges do not necessarily result in much protection for this species.

Bats are known to carry the causative virus of rabies

Because Idionycteris phyllotis is an insectivorous bat it plays an important role in pest control. Bat guano is used as a source of fertilizer, and organisms housed in the guano are used for waste detoxifying.

Comments: This species formerly included in the genus Plecotus (e.g., see Handley 1959). Hoffmeister (1986) cited external morphological, cranial, bacular, and chromosomal features in regarding Idionycteris as a genus distinct from Plecotus. Frost and Timm (1992) evaluated morphological and karyological characters and concluded that Idionycteris phyllotis and Euderma maculatum are sister species and that both belong in the genus Euderma (Idionycteris phyllotis would become E. phyllote). Chromosomal data presented by Qumsiyeh and Bickham (1993) also indicate a close relationship between Euderma and Idionycteris. However, Tumlison and Douglas (1992) examined morphological variation in plecotine bats and kept Idionycteris and Euderma as distinct genera. Jones et al. (1992) and Koopman (in Wilson and Reeder 1993) listed this species in the genus Idionycteris but did not cite the recent studies mentioned above. Bogdanowicz et al. (1998) examined morphological and chromosomal variation and concluded that Idionycteris phyllotis and Euderma maculatum should be regarded as generically distinct. In a study of mitochondrial ribosomal DNA sequences, Hoofer and Van Den Bussche (2001) confirmed that these two genera were indeed closely related, but percent sequence distance coupled with previous morphologic and karyotypic data supported generic distinction between the two. Simmons (in Wilson and Reeder 2005) treated Idionycteris phyllotis and Euderma maculatum as generically distinct.

Tumlison (1993) examined geographic variation in cranial characters and divided I. phyllotis into two subspecies, phyllotis and hualapaiensis; however, the latter was distinguished from the former by only its smaller size.