174.

Small Big-eared Brown Bat

Histiotus montanus

French: Sérotine des montagnes / German: Kleine GroRohrfledermaus / Spanish: Histiotus montano

Taxonomy. Vespertilio montanus R. A. Philippi & Landbeck, 1861,

Cordillera, Santiago, Chile.

Congeners H. alienus, H. laephotis, and H. magellanicus were previously considered subspecies of H. montanus, and its taxonomic status is confusing. It is frequently mistaken with H. laephotis and H. macrotus; therefore, accurate data from literature are scarce. Three subspecies recognized.

Subspecies and Distribution.

H.m.montanusR.A.Philippi&Landbeck,1861—S&SEBrazil,Uruguay,Argentina,andC&SChile.

H.m.colombiaeThomas,1916—AndesofVenezuela,Colombia,andEcuador.

H. m. inambarus Anthony, 1920 — Peru and N Chile; probably in W Bolivia.

Descriptive notes. Head—body c.51-67 mm,tail 40-55 mm, ear 20-29-5 mm, hindfoot 8-12 mm, forearm 42-5-51-1 mm; weight 9-13 g. Dorsal hairs of the Small Big-eared Brown Bat are bicolored, with black or dark brown bases and whitish tips; ventral hairs are strongly bicolored, with dark brown bases and white tips; some specimens are paler, with generally grayish venters. Ears are large, rounded, but relatively small compared with congeners; tragus is well developed, reaching one-half the ear length. Membrane connecting ears is usually absent but sometimes poorly developed. Membranes, face, and ears are pale light brown. Skull is robust; sagittal and lambdoidal crests are practically absent; zygomatic arches have strongly developed postorbital process of jugal; palateis slightly concave centrally; caudal spine is well developed; and tympanic bullae are large and rounded. I* is bicuspid; I’ is rudimentary and separated from C' by small gap; P* is robust and in contact with C' and M'; lowerincisors are tricuspid; and P, is one-half the height of P,. Chromosomal complement has 2n = 50 and FN = 48.

Habitat. Dry environments to humid forests in steppes, shrub grasslands, savannas, ombrophilous forests, semideciduous forests, dense rainforests, and araucaria forests from sea level up to an elevation of 4117 m.

Food and Feeding. Small Big-eared Brown Bats are aerial insectivores. Fecal and stomach samples contained fragments of Lepidoptera and Coleoptera, including Curculionidae (genus Pantomorus) and Tenebrionidae (genus Parepitragus).

Breeding. Pregnant Small Big-eared Brown Bats were captured in July-August and November-December in Ecuador and Argentina. Lactating females were captured in July in Ecuador. It is speculated that a female’s reproductive cycle starts at one year of age, and one young is born to each female per pregnancy.

Activity patterns. Small Big-eared Brown Bats commonly roost in caves but also loose rocks, holes and crevices, buildings, and hollow trees. Individuals seem to hibernate in the southern part of its distribution. Echolocation calls have downward FM component, followed by QCF component. Calls sweep down from ¢.46-53 kHz to ¢.25-29 kHz, with duration of c.3-5 milliseconds. Interpulse interval averages 144 milliseconds, intensity is ¢.38 dB, and peak frequencies are ¢.32-35 kHz.

Movements, Home range and Social organization. Small Big-eared Brown Bats usually form small colonies of5-20 individuals. They will share roosts with Brazilian Free-tailed Bats ( Tadanrida brasiliensis), Yellowish Myotis ( Myotis levis), and Red Myotis ( M. ruber).

Status and Conservation. Classified as Least Concern on The [UCN Red List. The Small Big-eared Brown Bat is widely distributed, presumably with large populations, and occurs in protected areas. In the southern part of its distribution,it seems to be particularly abundant.

Bibliography. Acosta (1950), Barquez & Diaz (2016b), Barquez, Carbajal et al. (2013), Barquez, Mares & Braun (1999), Berrocal (2016), Bianconi & Pedro (2017), Carvalho et al. (2013), Garbino (2016), Handley (1996), Handley & Gardner (2008), Miranda, Pulchério-Leite et al. (2006), Ossa et al. (2015), Rodriguez-San Pedro & Simonetti (2013a), Ruiz (2015), Simmons (2005), Williams & Mares (1978).