The Spotted bat has a patchy distribution, occurring from northern Mexico to British Columbia. They are seldom abundant. Recorded observations extend from the Pacific coast to the Rocky Mountains inland.

Biogeographic Regions: nearctic (Native )

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

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Western North America from southern British Columbia (north to Fraser River basin near Williams Lake) (Cannings et al. 1999) south through eastern Oregon, Idaho, south-central Montana, western Colorado, central Wyoming western Nevada, California (Pierson and Rainey 1998), southwestern Arizona, central New Mexico, western Texas, and central Mexico (Queretaro) (Verts and Carraway 1998). Winter range not known. An echolocation monitoring survey of distribution has been conducted (Fenton et al. 1987). Ranges from below sea level to 2450 m. Apparently widespread but rarely abundant.

Total length, 126 mm; tail, 51 mm; hind foot, 12 mm; ear, 47 mm; forearm 48.51 mm. The Spotted bat is so named for its three white spots located over each shoulder and on the rump. The surrounding dorsal fur is black while the ventral fur is light with dark underfur. The face is black and the ears and wings are pale.

Range mass: 16 to 20 g.

Length: 13 cm

Weight: 18 grams

Differs from other bats in the unique patterning of the fur and the extremely large ears.

• Terrestrial

Spotted bats have been found foraging in many different habitats, especially in arid or Ponderosa Pine forests, and marshlands. Because of the low frequency of their echolocation calls large open habitat is predicted to be preferred. However, it is believed that the distribution of suitable diurnal roosting sites is cause for the patchy distribution of this species. Spotted Bats roost in the small cracks found in cliffs and stony outcrops. They have been found as high as 3000m above sea level, and even below sea level in the deserts of California.

(Pierson and Rainey 1998; Poche 1981; Watkins 1977)

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; mountains

Comments: Found in various habitats from desert to montane coniferous stands, including open ponderosa pine, pinyon-juniper woodland, canyon bottoms, open pasture, and hayfields. Speculation has been made that captures outside coniferous forests reflect post-breeding wandering (Snow 1974). In British Columbia, foraged mainly in fields near pines and over marshes (Wai-Ping and Fenton 1989). Locally common in various habitats (pinyon-juniper woodland, riparian corridors, over river) in canyons in northwestern Colorado (Navo et al. 1992). Roosts in caves and in cracks and crevices in cliffs and canyons, with which this species consistently is associated; can crawl with ease on both horizontal and vertical surfaces (Snow 1974, van Zyll de Jong 1985); rests suspended by feet, with head down. In British Columbia, used same roost each night May-July, but not after early August (Wai-Ping and Fenton 1989). Winter habits poorly known.

Handley (1959) found that spotted bats were found primarily on open or scrub country. Of his 22 recorded occurrences, 13 were around houses. He suggested that since most were found in strange situations, departures were made from normal habitat in response to a stimulus of rather frequent occurrence. Handley felt that an explanation for the paucity of collections in natural situations is due to the bat's narrow habitat tolerance (Snow 1974).

In Garfield County, Utah, Easterla captured a spotted bat in an area which was treeless and rolling for several miles around the site and also surrounded by mountainous terrain. The predominant plant species were Artemisia (sagebrush) and Chrysothamnus (rabbitbrush). In the mountainous terrain, the predominant plant was Pinus ponderosa (yellow pine) (Snow 1974). In Utah, Snow (1974) reported that bats were captured over a waterhole near limestone cliffs with cracks.

In the Big Bend National Park in Texas, the spotted bat was captured near the only water source (a permanent pool) in many square miles. It was found in a shallow, barren, hot, dry canyon with walls of angled, buckled pink and red limestone. The predominant plant species were Larrea divaricata (creosote bush), Euphorbia antisyphilitica (candelilla), Hechtia scariosa (Hechtia), AGAVE LECHUGILLA (century plant), Opuntia rufida (blind pricklypear), and Fouquieria splendens (ocotillo) (Snow 1974).

Many bats in New Mexico were caught over waterholes near a sandstone cliff with numerous vertical cracks.

In Wyoming, associated with canyons, cliffs, and nearby permanent water (Priday and Luce 1999).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No 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.

Probably some migrate south for winter. At least for lower elevation locations, it appears not to migrate (WESTEC Services 1981). Possibly occupies coniferous stands in summer and migrates to lower elevations in late summer/early fall (Berna 1990, Barbour and Davis 1969). Present in southern British Columbia from at least May though August (Leonard and Fenton 1983).

Like most Microchiroptera, the Spotted bat is an echolocator, but uses very low frequencies to locate prey (9-12kHz). These frequencies limit the Spotted bat to catching large flying insects, apparently specializing on large moths that cannot detect echolocation calls of such low frequencies. Insects seem to be caught in the air at a rate of about one every 45 seconds, and most recorded foraging behavior occurred from 11 pm to 3 am.

(Wai-ping and Fenton 1989; Watkins 1977).

Comments: Insectivorous. Apparently feeds primarily on noctuid moths, sometimes beetles (Snow 1974; Schmidly 1977, 1991; Barbour and Davis 1969; van Zyll de Jong 1985). In British Columbia, flew 5-15 m above ground when foraging; foraging areas of different individuals overlapped (Wai-Ping and Fenton 1989). In southeastern Utah, fed on small insects within 2 m of the ground; sometimes captured insects on the ground (Poche and Bailie 1974), though this has been disputed. In Colorado, foraged at heights above 10 m (Navo et al. 1992).

One study stated that the bats hunted a regular beat and searched for prey in clearings in pine forest; the bat was extremely punctual in making its rounds and reached various points along its route at the same time every night. When in the clearings, the bat followed a definite circuit at or above treetop height. The bat spent approximately three to five minutes per clearing during the spring, and much longer during the summer, retracing its circuit in the clearing. The lengthier foraging in the summer is attributed to increased prey availability during the later season (van Zyll de Jong 1985). Another study found that a predictable pattern of foraging was observed in spring to midsummer (May to July), and a less predictable pattern later in the summer. At the beginning of the summer, foraging periods were long, and became shorter later in summer (van Zyll de Jong 1985). The contradiction in foraging strategies between the two studies was attributed to the variability of the bat's behavior in response to changes in one or more factors in the environment such a abundance and distribution of prey (Snow 1974).

The spotted bat hunts alone, and at least sometimes appears to maintain an exclusive foraging area (Leonard 1983). Neighboring bats show evidence of mutual avoidance and have been observed to turn away when encountering one another near the boundaries of their hunting areas. This mutual avoidance has been interpreted as a mechanism to avoid competition. When the neighbor is absent, an individual may show no hesitation in flying into an area avoided earlier. It is believed that a combination of the bat's echolocation call and conspicuous color pattern are used to maintain the spacing between bats (van Zyll de Jong 1985).

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

Estimated Number of Occurrences: 21 - 80

Comments: Unknown. New sites are currently (1998) being discovered (e.g., Priday and Luce 1999).

Unknown

Comments: Abundance is unknown. Very rare, at least in collections. From 1891-1965 only 35 specimens were reported in the literature. Since then, this bat has been more commonly captured (but very low numbers).

Apparently relatively solitary but may hibernate in small clusters (Whitaker 1980). In British Columbia, roosted solitarily during active season; appeared to maintain exclusive foraging areas (Leonard and Fenton 1983); foraged up to 6-10 km from day roost each night (Wai-Ping and Fenton 1989).

Apparently this bat is a rapid flyer. Many of them are injured in the mist nets, indicating a high rate of speed at the collision (Snow 1974). In flight, the ears project forward. The only times the ears are carried erect are when the bat is alert, usually just preparatory to flight. At all other times, the ears lie along the back and are slightly curved (Barbour and Davis 1969).

Vocalizations and Echolocation

The spotted bat makes a wide variety of sounds in communicating and foraging. The voice has been described as sounding like a soft, extremely high-pitched metallic squeak; a hissing noise and a ratlike squeak; and a typical bat chirp. This bat has also been heard clicking the teeth together and making grinding noises by gnashing the teeth. Previous to taking flight, the spotted bat makes clicking or ticking notes (Snow 1974).

The echolocation call is loud and high- pitched; the fundamental frequency sweeps from 12 to 6 kHz and is a double or single steep frequency modulated pulse. The call is repeated at a rate of two to six per second. The sound pressure level is estimated at 80-90 dB at 10 cm, making it a moderate intensity. The echolocation call can clearly be heard by a human at distances of 250 m (van Zyll de Jong 1985).

The low frequency of the echolocation call is useful in both hunting and communications. Due to reduced attenuation and good propogation qualities, the call is good for long-range detection of prey and an increased range of audibility by other bats. The bat is also able to approach the moth more closely and enhance the chance of a successful pursuit due to the moth not being able to detect the low intensity of sound (van Zyll de Jong 1985). Similar calls are made by PLECOTIS Phyllotis (Allen's big-eared bat), TADARIDA MACROTIS (big freetail bat), and Eumops perotis (western mastiff bat) (Snow 1974).

Comments: Nearly all of 54 individuals netted in western Texas were caught after midnight (Watkins 1977). In British Columbia, left day roost an average of 49 min after sunset (13 min in radio-tagged bats, Wai-Ping and Fenton 1989), returned an average of 67 min before sunrise; peak in foraging 0000-0300 h (Leonard and Fenton 1983); emergence from day roost was not significantly influenced by moonlight; flew continuously between departure from and return to day roost (Wai-Ping and Fenton 1989). In Colorado, active throughout the night (Navo et al. 1992, Storz 1995).

The female gives birth to one young weighing 20% of her body weight usually around June. Young do not have the spots of the adults, nor fully developed ears at birth. Juveniles have been caught in mist nets in July. Lactating females have been caught as late as August.

(Watkins 1977)

Range number of offspring: 1 to 1.

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

In the south, births apparently occur in late May or early June (Watkins 1977, Schmidly 1977). Time of birth in north may be somewhat later (van Zyll de Jong 1985). One pregnant bat captured in southwestern Texas gave birth to a single male on June 11 (Snow 1974, Schmidly 1977). A pregnant bat was collected in British Columbia on June 16. Lactating females have been netted on June 23, 30, and July 1 in New Mexico, on July 9 in New Mexico by Mike Bogan, and on August 10, 15, and 18 in Utah (Barbour and Davis 1969).

The males netted have not been examined for sperm but measurements of the testes of two bats have been taken. One male that died in captivity on August 27 had testes that measured 4 mm by 2 mm and a male netted on August 21 in Utah had testes that measured 7 mm by 3 mm (Barbour and Davis 1969). Evidence points to the birth of a single young in altricial condition.

Four hours after birth, a male appeared to nurse almost constantly for the first 48 hours. The mother showed great parental care to the young. She was gentle and attentive, licking the young's face, ears, wings, and back. The young stayed with her, attached to a teat, even when the female flew. She did not seem to be hindered by the additional weight. The female shielded the young with her wings when they were hanging upside down. No more is known about the young because the one born in captivity died at four and a half days when it became chilled after crawling through some drinking water (Snow 1974).

Very little is known about the distribution of the population of this bat. The lack of natural history data places it in class 2, requiring more information. Because the Spotted Bat seems to forage in various habitats, conservation of diurnal roosts, rocky cliffs that have snug cracks for roosting, seem to be the best way to protect this species. However large open foraging sights, where their echolocation is most effective, are important to the conservation of this species, as well as the availability of large moths as 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 Euderma maculatum mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Widespread in western North America; sparse, but more common than formerly believed. Abundance, population trend, and threats are essentially unknown.

Global Short Term Trend: Relatively stable (=10% change)

Comments: Unknown. Assumed stable.

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: Because of the lack of sufficient information, only speculations can be made about threats. Habitat destruction, such as construction of dams that inundate high cliffs and canyon walls, possibly is a threat (Snow 1974). Fenton et al. (1983) stated that the two highest threats to spotted bats appeared to be collection of specimens by humans, and the use of pesticides that the bats may accumulate through their diet and that kill their prey.

Restoration Potential: Until more is known, it is difficult to determine what can be done to increase the population of the spotted bat. It is probable that it has never been very common (Snow 1974).

Management Requirements: Not much management can be done until more ecological information is available. However, Snow (1974) recommended the following: 1) determine the presence of the spotted bat by surveying likely habitat 2) establish and maintain waterholes in likely spotted bat habitat (it is well known that the bat will fly for several miles to find water, and a water hole will benefit many species), 3) support and cooperate in studies to determine more about the impacts by humans.

Biological Research Needs: Determine habitat preferences, life history, reproduction, and patterns of movement.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: Unknown. Some roost sites or sightings on protected land, but entire occurrence may not be protected.

Needs: Protect known roost sites from disturbance. Collection of specimens should be carefully managed at least until more information on abundance is available.

unknown

Unknown, but as a specialist on moths they might be important in controlling specific moth populations

Stewardship Overview: The greatest management need is to obtain further information on current distribution and abundance, life history, ecology.

Comments: 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) listed Idionycteris phyllotis and Euderma maculatum as generically distinct.