176.

Common Big-eared Brown Bat

Histiotus macrotus

French: Sérotine a grandes oreilles / German: Gewohnliche GroRohrfledermaus / Spanish: Histiotus orejudo

Taxonomy. Nycticeius macrotus Poeppig, 1835,

Antuco, Bio Bio, Chile.

Histiotus laephotis has been previously considered a subspecies of H. macrotus .

It is frequently mistaken with H. laephotis and H. montanus, therefore, accurate data from literature are scarce. Monotypic.

Distribution. C Chile and NW, C & W Argentina. Records from Peru should be reviewed.

Descriptive notes. Head-body ¢.59-65 mm, tail 48-62 mm, ear 28-34 mm, hindfoot 9-11 mm, forearm 45-9-50-9 mm; weight 10-3-20 g. Dorsal hairs of the Common Big-eared Brown Bat are strongly bicolored, with black or dark brown bases and yellowish tips; ventral hairs have dark brown bases and yellowish white tips. Ears are extremely large; tragusis well developed. Membrane connecting ears is poorly developed. Membranes, face, and ears are brown to dark brown, notably darker than body. Skull is robust; rostrum is wide; sagittal and lambdoidalcrests are practically absent; zygomatic arches have strongly developed postorbital process ofjugal; palate is slightly concave centrally; caudal spine is well developed; and tympanic bullae are large and rounded.

Habitat. Great variety of habitats ranging from deserts to montane rainforests, including Dry Chaco, Espinal, Yungas, Patagonian forests and steppes, temperate forests, moist montane Chacoan forests, desert and rocky canyons, and mature forests at elevations of 240-3600 m. Common Big-eared Brown Bats have been captured over streams, ponds, and irrigation canals.

Food and Feeding. Common Big-eared Brown Bats are insectivorous. Feces contained fragments of Lepidoptera (36-6% by frequency), Coleoptera (30-6%), Trichoptera (13.6%), Diptera (9-8%), and Acari (1-7 %).

Breeding. In Rio Negro, Argentina, pregnant and lactating Common Big-eared Brown Bats were captured in December; pregnant females carried only one embryo.

Activity patterns. Common Big-eared Brown Bats usually roost in mines, natural caves, buildings, and rocky crevices.

Movements, Home range and Social organization. The Common Big-eared Brown Bat is usually solitary in central Chile, but in other parts ofits distribution, colonies from 20 to hundreds of individuals were found. It will share roosts with Brazilian Free-tailed Bats ( Tadarida brasiliensis) and Myotis spp.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Common Big-eared Brown Batis widely distributed, presumably with large populations. It is relatively common in northern Chile but seems uncommon in Argentina.

Bibliography. Aragon & Aguirre (2014), Barquez & Diaz (2016a), Barquez et al. (1999), Giménez (2010), Giménez et al. (2015), Handley & Gardner (2008), Lopez-Gonzélez et al. (1998), Mann (1978), Mares et al. (1995), Simmons (2005).