Gray Sac-winged Bat

Description

The Gray Sac-winged Bat flies with an erratic pattern and rapid wingbeats, very distinct from the more gliding flight of other bats of its size. It moves in small groups, emerging from its day roosts shortly after sunset to hunt insects in open spaces next to water bodies or vegetation clearings. It lives in caves, rock crevices, and occasionally human constructions in a strip of the Mexican and Central American Pacific coast, where it forms colonies that can reach several hundred individuals grouped on the walls of the roost. It belongs to a family of bats with a characteristic fold in the wing membrane. This feature gives the Gray Sac-winged Bat its name and

How to identify it

The Gray Sac-winged Bat is a small bat with greyish-brown fur, narrow, pointed wings adapted for fast flight, and no nose-leaf. It is distinguished from other small insectivorous bats in its area by its especially fast and erratic flight. It also forms dense, visible colonies on cave walls and rock crevices.

Signs and tracks

Peak energy frequency is variable, approximately 25-45 kHz, with a downward frequency-modulated (FM) sweep that ends in a quasi-constant frequency (QCF) tail. On a detector screen, this appears as a curved trace falling from high pitches to an almost flat final section. The minimum sweep frequency varies notably with habitat and social context, dropping to 22-

Habitat and range

Caves, rock crevices, and human constructions in areas of dry tropical forest and arid scrubland, from lowlands to mid-altitudes. Distributed across the Pacific side of Mexico and Central America.

Diet

Insectivorous, it feeds on small flying insects captured in rapid flight over open spaces, often near water bodies.

Behaviour

The Gray Sac-winged Bat forms numerous, dense colonies in caves and rocky crevices. Emergence is highly synchronised, occurring shortly after sunset. Its flight is fast and erratic, very distinct from the slower flight of other insectivorous bats of its size.

Conservation

Its populations are considered stable throughout most of its home range, with no signs of significant decline.

Threats

Disturbance of cave colonies due to tourist or extractive activity, and habitat loss due to deforestation in some areas.

Other accounts in Emballonuridae

• Bare-rumped Sheath-tailed BatSaccolaimus saccolaimus
• Black-bearded Tomb BatTaphozous melanopogon
• Greater Dog-like BatPeropteryx kappleri
• Greater Sac-winged BatSaccopteryx bilineata
• Lesser Dog-like BatPeropteryx macrotis
• Lesser Sac-winged BatSaccopteryx leptura
• Lesser Sheath-tailed BatEmballonura monticola
• Long-winged Sheath-tailed BatTaphozous longimanus
• Mauritian Tomb BatTaphozous mauritianus
• Northern Ghost BatDiclidurus albus
• Proboscis BatRhynchonycteris naso
• Theobald's Tomb BatTaphozous theobaldi

See all species accounts for bats · Full species index