Emballonuridae Author Bonaccorso, Frank text 2019 2019-10-31 Lynx Edicions Barcelona Editor Wilson, Don E. Editor Mittermeier, Russel A. Handbook of the Mammals of the World – Volume 9 Bats 350 373 book chapter 10.5281/zenodo.3740269 34e4a5a6-881c-4a1a-b64d-6868e12df7fb 978-84-16728-19-0 3740269 35 . Thomas’s Sac-winged Bat Balantiopteryx io French: Emballonure de Thomas I German: Thomas-Sackflügelfledermaus / Spanish: Embalonuro de sacos de Thomas Other common names: Least Sac-winged Bat Taxonomy . Balantiopteryx io Thomas, 1904 , “ R[ioJ. Dolores, near Coban [ Alta Verapaz ], Guatemala .” This species is monotypic. Distribution. Atlantic slope of Mexico and Central America from S Veracruz and Oaxaca to E Guatemala and Belize. Descriptive notes. Head—body 38-44 mm, tail 8—18 mm, ear 10—13 mm, hindfoot 7-8 mm, forearm 36-41-4 mm; weight 3-4 g. Dorsal fur of Thomas’s Sac-winged Bat is dark brown to black; venter is paler gray-brown. Flight membranes are black. Wings attach to ankles. Habitat . Semideciduous or evergreen forests from sea level to elevations of c .500 m. In the Maya Mountains of Belize, Thomas’s Sac-winged Bat occurs in semideciduous forest. Food and Feeding . Thomas’s Sac-winged Bats forage on small, aerial insects. Although direct visual observations are difficult due to their late emergence from roost, echolocation call characteristics suggest that they hunt in clutter close to vegetation of forest habitats or over water. Breeding . Pregnant Thomas’s Sac-winged Bats have been recorded in March, May, and July, suggesting polyestry . Activity patterns. Thomas’s Sac-winged Bats are nocturnal. They roost widely and evenly spaced, often occupying dark recesses of large, limestone caves on ceilings of high chambers. Activity starts well after sunset, later than related species. Echolocation calls include long narrowband component and maximum amplitude on second harmonic. Thomas’s Sac-winged Bats show slightly downward narrowband component that initially starts at 50-2 kHz and drops to 45-9 kHz, on average, and does not turn upward as in other genera of forest emballonurids. Average call duration is 7-8 milliseconds. During approach and terminal phases, call changes to obtain accurate target information after potential prey has been detected. Movements, Home range and Social organization. Groups of Thomas’s Sac-winged Bats commonly number 50 or more individuals and occasionally 1000—2000 individuals in large caves. Status and Conservation . Classified as Vulnerable on The IUCN Red List. Thomas’s Sacwinged Bat because depends on highly fragile forested habitat, and it is estimated to have declined by more than 30% due to habitat loss and degradation in the last ten years, with remaining subpopulations fragmented. Adventure tourism leading to vandalism in caves has been and is a significant threat, particularly in Belize, Yucatan , and Guatemala. Needed conservation actions include management and protection of roost caves and additional protection of rapidly disappearing Atlantic forests. Bibliography. Arroyo-Cabrales & Jones (1988b), Lim, Engstrom et al. (2004), Reid (2009), Thomas (1904b), Villa (1967).