249.

Spotted Bat

Euderma maculatum

French: Oreillard maculé / German: Gefleckte Fledermaus / Spanish: Orejudo maculado

Other common names: Pinto Bat

Taxonomy. Histiotus maculatus J. A. Allen, 1891, “ ‘caught on a fence,’ at Piru [Santa Clara River Valley], in the western part of Ventura County, California.”

Based on morphological and chromosomal characters, the genus Idionycteris has been included under Euderma as a synonym, but they differ enough to be generically distinct. Molecular reconstructions based on mitochondrial and nuclear genes support distinction of Euderma and Idionycteris at the generic level and also showed a controversial positioning of Euderma within plecotines and lasiurines. Despite morphological similarity between Euderma and plecotines, the genusis included in Lasiurini by recent phylogenetic studies. Monotypic.

Distribution. From British Columbia in SW Canada and Montana and Wyoming in NW USA S to Querétaro in C Mexico.

Descriptive notes. Head-body ¢. 60-65 mm, tail 47-50 mm, ear 37-50 mm, hindfoot c. 12 mm, forearm 48-51 mm; weight 16-20 g. Dorsalfuris blackish, with white spots of c. 15 mm in diameter on shoulders and lower back; ventral hair is snow white, with black bases, and band of blackish hairs circles neck. Non-glandular naked area of c. 10 mm in diameter occurs on throat region that is visible only when head is tipped backward. Old World Glauconycteris is the only genus with comparable color. Ears are very long, almost reaching body length, translucent pale pink, and naked along their lengths, with tuft of white hair at bases and connected across forehead by small membrane. Tragus is elongated and slightly narrowed at tip, basal lobe is absent, and basal notch is indeterminate. Thin and pliable wing membranes and uropatagium are pale pink. Skull has supraorbital region that is sharply ridged, braincase is remarkably elongated, and sagittal crestis absent. C,is small compared with other taxa within the subfamily, appearing unequally bilobed in slightly anterior to lateral view. Dental formulais12/3,C1/1,P 2/2, M 3/3 (x2) = 34. Chromosomal complement has 2n = 30 and FN = 52, which is most similar to Allen’s Big-eared Bat ( Idionycteris phyllotis), differing by presence of subtelocentric autosome pair in the Spotted Bat rather than medium-sized acrocentric pair.

Habitat. Wide variety of habitats including desert shrub and arid areas, forest openings, woodlands, riparian habitats, wetlands, open areas near streams and ponds, meadows, and old agricultural fields from below sea level in deserts of California up to elevations of ¢. 3000 m in Mexico.

Food and Feeding. Analysis of feces and stomach contents showed that Spotted Bats specialize on large moths (mostly Noctuidae), constituting ¢.99% of diets by volume; they also eat beetles ( Coleoptera). It is a fast flier and forages alone 10-30 m aboveground. It is often captured in open areas and open ponderosa pine ( Pinus ponderosa, Pinaceae) woodlands. Moonlight does not seem to affect foraging behavior.

Breeding. A pregnant Spotted Bat was caught in June and lactating females in June and August. Littersize is likely one. Newborns weigh ¢.20% of mothers’ weights. Ears of young are not completely developed, and spots are missing. Young have been captured in July.

Activity patterns. The Spotted Bat tends to fly late, with most captures occurring after midnight. Nevertheless, foraging activity has been recorded throughout the night, and some individuals were observed foraging as early as 20 minutes after sunset. Day roosts are located in crevices of cliffs and outcrops and apparently not in trees. It produces low-frequency echolocation calls that appear to be inaudible to large moths and can be divided into search, approach, and terminal phases. Search phase is divided in two types of calls that are steep, FM, and include different harmonics; frequency sweeps from 12 kHz to 6 kHz. The approach calls are also divided in two forms, which are similar to search calls and include FM pulses and sweeps. Predators include red-tailed hawks (Buteo jamaicensis), peregrine falcons (Falco peregrinus), American kestrels (Falco sparverius), and belted kingfishers (Megaceryle alcyon).

Movements, Home range and Social organization. Spotted Bats have been found roosting alone, except during hibernation when four individuals were found hibernating in a cave. Foraging individuals avoid contact with other species of echolocating bats and keep a distance of at least 50 m from other foraging conspecifics. Foraging usually occurred within 10 km from diurnal roost, but movements up to 38- 5 km from day roosts to foraging areas were recorded. Absence of winter captures and records in caves and mines in Wyoming suggest that Spotted Bats migrate or use hibernacula other than underground sites. Winter activity in south-western Utah was associated with poor hibernacula in the area.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Spotted Bat is widespread but considered rare. Loss of roosting and foraging areas, destruction or disturbance of hibernacula, and loss of clean and open water are major threats.

Bibliography. Allen, H. (1893), Allen, J.A. (1891), Amador et al. (2018), Arroyo-Cabrales & Alvarez-Castafneda (2017a), Easterla (1973), Hall (1981), Handley (1959), Hussain (2000), Leonard & Fenton (1984), Leén-Paniagua (2014), Luce et al. (2004), Mikula et al. (2016), Painter et al. (2009), Poché (1981), Ross (1967), Shi & Rabosky (2015), Simmons (2005), Watkins (1977), Williams et al. (1970), Wilson & Ruff (1999).