Cormura brevirostris (Wagner, 1843)

Bonaccorso, Frank, 2019, Emballonuridae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 350-373 : 364

33 . Chestnut Sac-winged Bat

Cormura brevirostris

French: Cormure des souches / German: Kastanienbraune Sackflügelfledermaus / Spanish: Cormura castano

Other common names: Wagner's Sac-winged Bat

Taxonomy. Emballonura brevirostris Wagner, 1843 ,

“ Marabitanas .” Corrected by A. von Pelzeln in 1883 to “Baraneiva” and clarified by D.. Carter and P. G. Dolan in 1978 as “Bananeira (approximately 10°39’S, 65°23’W), on the Rio Mamore (there forming the boundary between Brazil and Bolivia), in the state of Mato Grosso .”

This species is monotypic.

Distribution. Widely distributed in Central and South America, from E Nicaragua to Panama, W of the Andes to NW Ecuador, and E of Andes from Venezuela and the Guianas to Amazonian Peru, C Brazil and N Bolivia.

Descriptive notes. Head—body 46-58 mm, tail 10—16 mm, ear 13-16 mm, hindfoot 5-8 mm, forearm 41-50 mm; weight 7-11 g. Dorsal fur of the Chestnut Sac-winged Bat is thick, shiny, and chestnut-brown, with underparts slightly paler. Fur almost reaches tip of nose, but lower face is naked. Subadults andjuveniles have black fur. Facial skin, ears, and flight membranes are black. Ear is oval-shaped, and inner surface of pinna is heavily ribbed. Tragus is broad and square-topped. Wings attach to base of toes. Both sexes have wing sacs, which are vestigial in females; in breeding age males, they are large with opening extending to edge ofwing and outward from body. Calcar is about twice as long as foot. Tail is short, with free end extending at most 3 mm above tail membrane; tail membrane extends well beyond toes when extended. Skull has welldeveloped sagittal crest that is more robust in males. Upper incisors are minute. Lower incisors are slightly larger and form continuous row between canines. Dental formula is 11/3, C 1/1, P 2/2, M 3/3 (x2) = 32. Karyotype is 2n = 22.

Habitat. Along streams and forest edges in moist lowland multi-strata tropical evergreen forests from sea level to elevations of c.1000 m. The Chestnut Sac-winged Bat forages in small open spaces including forest edges and tree fall gaps, flying in long, slow, beats between ground level and forest canopies.

Food and Feeding. The Chestnut Sac-winged Bat is an aerial insectivore that capably forages in cluttered space. When foraging in areas with Greater Sac-winged Bats ( Saccopteryx bilineata ) or Lesser Sac-winged Bats ( S. lepturd ), Chestnut Sac-winged Bats partition space by foraging higher aboveground (5-10 m) or farther from vegetation in gaps and forest edges. It flies faster and in wider circles (20-30 m across) than the Saccopteryx species.

Breeding. In Panama, female Chestnut Sac-winged Bats are pregnant in April-May but not in June—September. In French Guiana, females are pregnant in August- September. Litter size is not reported.

Activity patterns. Chestnut Sac-winged Bats are crepuscular. Foraging activity begins at dusk and continues for 10-15 minutes, after which observers found individuals to fly above the canopy and disappear, perhaps moving to different foraging areas. Foraging in the middle of the night is rare, but a secondary foraging period occurs shortly before dawn. The Chestnut Sac-winged Bat roosts in tree hollows of living, rotting, and fallen trees and under concrete bridges. One group clung to underside of a large leaf of South American traveler’s palm { Phenakospermum guyannense , Strelitziaceae ). The Chestnut Sac-winged Bat emits search-phase echolocation calls in triplet pulses, with each subsequent sound pulse 2-3 kHz higher than the preceding pulse. First pulse has mean frequency of 25-4 kHz that rises to 28-7 kHz and 32-1 kHz on second and third pulses, respectively. Mean durations of these pulses are 5—10 milliseconds, and mean pulse intervals are 84-102 milliseconds. Chestnut Sac-winged Bats use search calls with components that are dominated by narrowband and small FM parts. These characteristics are well suited for detection of flying insects from relatively long-range detection distances, and similarly used by other members of the tribe Diclidurini .

Movements, Home range and Social organization. Chestnut Sac-winged Bats roost in small groups. In French Guiana, roosting groups consisted of 2-5 individuals clustered in compact masses, with individuals touching each other back to belly in a stacked formation. Roosting groups in French Guinea sometimes consisted of more than one adult male but never more than one adult female. Females are able to locate young by contact calls emitted by young, which have been experimentally documented by a mother coming to a captive offspring held in a cloth bag.

Status and Conservation. Classified as Least Concern on 77/r IUCNRed List. The Chestnut Sac-winged Bat has a large distribution, and there is no evidence of rapid population decline. In general, deforestation is a threat; however, taken in context of its large area of endemism, that threat is not presently a serious concern, especially because it occurs in protected reserves throughout its distribution. Chestnut Sac-winged Bats are locally common in the Amazon Basin and uncommon in Central America lowland moist and wet forests, but it is not well studied because of limitations of early field investigations. As acoustic detection methodology is now becoming more common in Central America and South American, and such surveys likely will provide valuable insight on distribution and ecology of the Chestnut Sac-winged Bat Its distribution follows areas of moist lowland forests, but due to loss of these forests, it might no longer occur in southernmost parts of its distribution.

Bibliography. Barclay (1983), Bernard (2003), Carter & Dolan (1978), Emmons & eer (1997), Fleming eta/. (1972), Hood & Gardner (2008), Kalko (1995a), Linares (1998), von Pelzeln (1883), Peters (1867a), Reid (2009), Simmons & Voss (1998), Wagner (1843).

Figures

On following pages: 22. New Guinea Sheath-tailed Bat (Emballonura furati); 23. Beccari's Sheath-tailed Bat (Emballonura beccarti); 24. Large-eared Sheath-tailed Bat (Emballonura dianae); 25. Seri'sSheath-tailed Bat (Emballonura sertii); 26. Pacific Sheath-tailed Bat (Emballonura semicaudata); 27. Western Sheath-tailed Bat (Paremballonura tiavato); 28. Peters's Sheath-tailed Bat (Paremballonura atrata); 29. African Sheath-tailed Bat (Coleura afra); 30. Seychelles Sheath-tailed Bat (Coleura seychellensis); 31. Madagascar Sheath-tailed Bat (Coleura kibomalandy); 32. Dark Sheath-tailed Bat (Mosia nigrescens); 33. Chestnut Sac-winged Bat (Cormura brevirostris); 34. Gray Sac-winged Bat (Balantiopteryx plicata); 35. Thomas's Sac-winged Bat (Balantiopteryx io); 36. Ecuadorian Sac-winged Bat (Balantiopteryx infusca).

Distribution. Widely distributed in Central and South America, from E Nicaragua to Panama, W of the Andes to NW Ecuador, and E of Andes from Venezuela and the Guianas to Amazonian Peru, C Brazil and N Bolivia.