171.

Tropical Big-eared Brown Bat

Histiotus velatus

French: Sérotine voilée / German: Tropische GrofRohrfledermaus / Spanish: Histiotus tropical

Taxonomy. Plecotus velatus 1. Geoffroy Saint-Hilaire, 1824,

Curitiba, Parana, Brazil.

Taxonomic status of Histiotus velatus is somewhat uncertain; in the past, more than one form seemed to exist in its wide distribution.

Taxonomic revision is needed. Monotypic.

Distribution. Peru, Bolivia, C & S Brazil, S Paraguay, and NE Argentina.

Descriptive notes. Head-body 58-2-70-8 mm, tail 46-60 mm, ear 24-3 33-5 mm, hindfoot 6-11 mm, forearm 42-50 mm; weight 9-17 g. Tibia lengths are 18-8-20-2 mm. Dorsal hairs of the Tropical Big-eared Brown Bat are slightly bicolored, with blackish brown bases and lighter cinnamon-brown tips; ventral hairs have dark brown bases and grayish to dark chestnut tips. Ears are very large, triangular, brown to dark brown, and connected by well-developed membrane (c. 3 mm high) across forehead; tragus is long, broad, and rounded at tip. Membranes are naked and brown to dark brown. Calcar is well developed. Skull is robust, narrower than observed in congeners; sagittal and lambdoidal crests are practically absent; zygomatic arches have strongly developed postorbital process ofjugal; palate is slightly concave centrally and narrower than in congeners; caudal spine is well developed; and tympanic bullae are large and rounded.

Habitat. Wide variety of habitats including moist forests, savannas in grasslands, evergreen forests, semideciduous forests, open and shrub savannas, plantations, and urban areas from sea level up to elevations of ¢. 2400 m.

Food and Feeding. Tropical Big-eared Brown Bats are insectivorous. In south-eastern Brazil, a small group preyed on flying winged termites (Isoptera). Feces contained fragments of Lepidoptera, Hymenoptera, Coleoptera, and Araneae ( Pholcidae and Araneoidea).

Breeding. In southern Brazil, pregnant Tropical Big-eared Brown Bats were captured in October-December, one female captured in October had two embryos, and young were observed in late October-November and early December. Available data suggest that parturition is synchronized and takes place once a year in spring.

Activity patterns. Tropical Big-eared Brown Bats are nocturnal. Individuals were observed leaving roosts at sunset, and captures occurred during the first two hours after sunset. Roosts have been found in buildings, such as inside of churches and roofs. Study of a colony in southern Brazil showed that individuals were “asleep” ¢.75% of the time and “alert” ¢.17% of the time during the day; sometimes all individuals in the colony were sleeping. Number of individuals in the colony changed throughout the year: up to 70 individuals in spring and summer and down to 10 individuals in autumn and winter. Movements are closely related to oscillations in temperature and photoperiod. Echolocation calls sweep down from 25 kHz to 15 kHz, with durations of 5-8 milliseconds.

Movements, Home range and Social organization. Colonies of Tropical Big-eared Brown Bats can be 6-12 individuals up to 70 individuals. They share roosts with Pallas’s Mastiff Bats (Molossus molossus) and Silver-tipped Myotis ( Myotis albescens).

Status and Conservation. Classified as Data Deficient on The IUCN Red List. The Tropical Big-eared Brown Bat occurs in protected areas. Deforestation might be a threat, but additional research is needed to clarify it conservation status.

Bibliography. Barquez et al. (1999), Bianconi & Pedro (2017), Feijé, Rocha & Althoff (2015), Fenton, Whitaker et al. (1999), Gonzalez & Barquez (2016¢), Handley & Gardner (2008), Lopez-Gonzélez (2004), Nora & Chaves (2006), Simmons (2005), Thomas (1916b), Vizotto & Taddei (1973), Welter (2009).