FIELD FILE · AHOOLFLYINGREGIONAL LEGEND

Ahool

Also known as Athol, Giant bat of Java

A giant, monkey-faced bat said to swoop over the waterfalls of Java’s Mount Salak, named after its eerie “a-hool” cry in the night.

The ahool is a gigantic bat said to live in the rainforests of western Java, Indonesia, particularly around the volcano Mount Salak south of Bogor. Its name is said to imitate its call – a long, rising “a-hooool” heard after dark – and that sound is at the heart of most stories about it.

The legend reached the outside world through Ernst Bartels, a naturalist from a family of Dutch-German ornithologists who lived and collected birds in Java. According to the account he later gave, in 1925 he was exploring a waterfall on the slopes of the Salak mountains when an enormous bat-like animal flew directly over his head. Two years later, he said, he was lying awake in a hut near the Tjidjenkol River when he heard the call pass over the roof and fade away downstream.

Bartels’ experiences were passed to the founders of modern cryptozoology, Bernard Heuvelmans and Ivan T. Sanderson. Sanderson, who claimed his own encounter with a giant bat in Cameroon (the olitiau), concluded that the ahool was an unclassified bat. More speculative writers later suggested a surviving pterosaur – an idea that does not fit the furred, monkey-faced animal witnesses describe.

Some later writers have wondered whether Bartels saw and heard not a bat at all but a very large owl. Today the ahool survives mostly in books and online lists of cryptids, and as a story told on Java about the dark slopes of Mount Salak, a mountain with plenty of folklore of its own.

Type

Flying

Status

Regional legend

First reported

1925

Best-known location

Mount Salak and the rainforests of western Java

Also called

Athol, Giant bat of Java

Reported in

Indonesia

What witnesses describe

Described as a bat with a wingspan of around three metres, a flattened monkey- or ape-like face with large dark eyes, short grey fur and long claws on its forearms. It is said to crouch on the forest floor with its wings folded and to fly low over rivers at night, hunting fish.

Where and when it’s seen

Remote rainforest in western Java, especially river valleys and waterfalls on Mount Salak, where it is said to roost by day in caves behind or beneath the falls and emerge at night.

Notable sightings

1. 1925The bat over the waterfall Salak mountains, West Java

   Naturalist Ernst Bartels reported that a huge, unfamiliar bat flew directly over his head while he was exploring a waterfall on the mountain’s slopes. This is the founding account of the ahool.

2. 1927The cry over the hut Near the Tjidjenkol River, West Java

   Late one night Bartels said he heard the distinctive “a-hool” call directly above his hut, grabbed a torch and ran outside, but the sound moved away downstream.

What could explain it?

• Large flying foxes (Pteropus vampyrus), called kalong in Indonesia, live on Java and have wingspans of up to 1.5 metres – huge enough to astonish anyone seeing one pass close overhead in the dark.
• An owl has also been suggested. Java is home to a large, dark-eyed, flat-faced wood owl (Strix bartelsi) named after the Bartels family, and an owl’s silent flight and haunting call fit the story well.
• Wingspans are notoriously hard to judge at night or against the sky, and the ahool’s three-metre span rests on brief, unmeasured glimpses.
• There is no specimen, photograph or recording; the legend rests almost entirely on one naturalist’s recollections as retold by cryptozoology writers.

Legend, culture and tourism

The ahool is better known in international cryptozoology books, games and websites than in Javanese tradition, but Indonesian media still revisit it as one of Mount Salak’s mysteries. The mountain itself, part of Gunung Halimun Salak National Park, is a popular hiking destination with waterfalls such as Curug Seribu – the kind of setting where the ahool is said to roost.

Places to visit

Where it’s reported

Indonesia West Java

Ahool in the news

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First published October 13, 2026 · Updated October 14, 2026