Euderma maculatum

Huge pink ears (37-47 mm [Hall 1981] or 45-50 mm [Watkins 1977]); blackish dorsum with a large white spot on each shoulder and on the rump, and white patches at the posterior base of each ear; total length 107-115 mm; forearm 48-51 mm; 16-20 g; greatest length of skull 18.4-19.0 mm (small sample); supraorbital region of skull sharply ridged; no median sagittal crest; 34 teeth (Watkins 1977, Handley 1959, Hall 1981). The newborn young lack any indication of having the adult color pattern (van Zyll de Jong 1985). Four hours after birth, a male weighed 4 g and measured 59 mm in length; tail length was 20 mm, hind foot 11 mm, ear 12 mm, and forearm 21 mm.

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

This species occurs in various habitats from desert to montane coniferous stands, including open ponderosa pine, pinyon-juniper woodland, canyon bottoms, riparian and river corridors, meadows, open pasture, and hayfields. Active foraging may be mostly in open terrain, including forest clearings, meadows, and open wetlands, sometimes in open areas near buildings (see review in Schmidt 2003) or even golf courses. Roosts, including maternity roosts, generally are in cracks and crevices in cliffs (Wai-Ping and Fenton 1989, Pierson and Rainey 1998, Rabe et al. 1998), sometimes in caves or in buildings near cliffs (Sherwin and Gannon 2005). Winter habits poorly known.

In British Columbia, individuals used the same roost each night May-July, but not after early August (Wai-Ping and Fenton 1989). They foraged mainly in fields near pines and over marshes (Wai-Ping and Fenton 1989).

In Wyoming, these bats were associated with canyons, cliffs, and nearby permanent water, in areas including xeric-shrub grassland, riparian woodland, and high-elevation conifer and aspens habitats (Priday and Luce 1999).

In northwestern Colorado, spotted bats are locally common in various habitats (pinyon-juniper woodland, riparian corridors, over river) in canyons (Navo et al. 1992).

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

In northern Arizona, radio-tagged individuals foraged mostly in desert scrub but also used woodlands and forests. Maternity roosts were remote and difficult to access (Chambers et al. 2011).

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

In the Big Bend National Park in Texas, spotted bats were captured near the only water source (a permanent pool) in many square miles, in a shallow, barren, hot, dry canyon with walls of angled, buckled pink and red limestone. The predominant plant species were creosote bush, candelilla, Hechtia, agave, pricklypear, and ocotillo (Snow 1974).

Apparently relatively solitary but may hibernate in small clusters (Whitaker 1980). In British Columbia, individuals roosted solitarily during the active season; appeared to maintain exclusive foraging areas (Leonard and Fenton 1983).

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 propagation 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).

Copulation likely occurs in late summer or fall. Births apparently occur in late May or early June in the south (Snow 1974, Watkins 1977, Schmidly 1977), mid-June to early July in the north (Watkins 1977, Nagorsen and Brigham 1993). Litter size is one. 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). Females are not known to form maternity colonies (Hayes and Wiles 2013).