The Ahool is a giant bat reported from the mountain rainforests of western Java, Indonesia. It is said to have a wingspan of around three meters (ten feet), a flat, monkey-like face and a loud call that gives it its name: a-hool. The story entered Western writing through the naturalist Ernst Bartels, who described an encounter on Mount Salak in 1925.[1][2] The strongest explanation points to an owl named after his own father.
| Type | Reported giant bat |
|---|---|
| Region | Western Java, especially the Mount Salak range |
| Reported size | Wingspan around 3 m (10 ft); body as large as a one-year-old child in some accounts |
| Reported features | Gray fur, large dark eyes, a flat face, large claws on the forearms, a loud “a-hool” call |
| First Western report | Ernst Bartels, c. 1925 |
| Physical evidence | None |
The Bartels report
Ernst Bartels came from a family of naturalists in the Dutch East Indies. His father, Max Bartels, was a well-known ornithologist in western Java, and several Javan birds are named after him. In 1925, according to later accounts, Ernst was exploring the forests of the Salak mountains when a huge, bat-like animal swooped low over him. He later reported hearing its distinctive call, rendered as “a-hool.”[1][2]
Bartels’ account reached English readers through the cryptozoologists Ivan T. Sanderson and Bernard Heuvelmans, who treated him as the first Western witness.[2] Reference works give the reported features as a wingspan of about ten feet, gray fur, large dark eyes, a flattened, monkey-like face and claws on the forearms.[3][4]
Some popular sites add a “blood-curdling scream heard for miles,” attacks on people or links to pterosaurs. Those details go well beyond the reported sightings.
The Bartels family of Pasir Datar
The witness matters to this story, because the Bartels were not casual travelers. Max Eduard Gottlieb Bartels, a naturalist of German-Dutch background, settled in West Java and built a home, private museum and field station at Pasir Datar near Sukabumi, at the foot of the mountains south of Bogor. From there the family collected birds, mammals and plants for decades. The Javan hawk-eagle (Nisaetus bartelsi) and the Javan owl (Strix bartelsi) are both named after him, and the family is credited with discovering about 21 species of birds, bats and rodents.[7]
Max Bartels had three sons, Max Jr., Ernst and Hans, all of whom shared his interest in natural history. Max Jr. (1902–1943) studied biology at the University of Bern and made zoological collections across western Java in the 1930s. He was interned after the Japanese invasion and died in a Japanese camp in Thailand in 1943. During the occupation the Pasir Datar house was looted, and much of the family’s research material was lost or later taken to the Netherlands.[7][8]
Ernst, the second son, is the Bartels linked to the ahool. That cuts both ways. On one hand, a member of a family of professional collectors would know Java’s fauna better than almost anyone, which is why cryptozoologists treat his report as significant. On the other hand, his account is known only secondhand, through Sanderson and Heuvelmans. We have not been able to find a published first-hand description by Bartels himself, so it is impossible to say exactly what he claimed to have seen and heard, or when.[2]
Related reports
- Sanderson’s olitiau (1932). While collecting animals in the mountains of Cameroon, Ivan Sanderson described a huge, dark, bat-like creature that swooped at him over a river. He later suggested the ahool and the African olitiau and kongamato might be related.[3][5]
- Other giant bats. Similar reports exist across the region, including the Ropen of Papua New Guinea, though accounts and descriptions vary widely.
Possible explanations
- The Javan owl. The Javan wood-owl, Strix bartelsi, is named after Max Bartels. It is a large, rarely seen owl of Java’s mountain forests, with a flat face, large dark eyes, grayish-brown underparts, silent flight and a loud single hoot. Territorial owls make mock dives at intruders. Its wingspan is about 1.2 m, and frightened witnesses at dusk often overestimate size.[4][6] It matches the face, the eyes, the call and the swooping behavior well.
- Large flying foxes. The large flying fox (Pteropus vampyrus), which lives on Java, is among the biggest bats in the world, with a wingspan of up to about 1.5 meters. Flying foxes have dog-like rather than flat faces and mostly squabble and screech at their roosts, but a large one seen briefly overhead could easily be mistaken for something bigger.
- An unknown species. Cryptozoologists have proposed an undiscovered giant bat, possibly an insect- or fish-eater. Java is a densely populated island with a long history of biological collecting, and no specimen, photograph or bone has turned up.[3]
No known bat can produce a loud, owl-like call carrying across a valley, which is a strong reason to think the ahool’s famous cry belongs to a bird.[4]
A closer look at the candidates
The large flying fox is a serious animal in its own right. It is the world’s largest bat by wingspan, at more than 1.5 meters, and it roosts in noisy colonies and flies long distances at night to feed on fruit and nectar. It is also heavily hunted for food and sport. A 2009 study led by Jonathan Epstein in the Journal of Applied Ecology found that about 22,000 were legally shot each year in Peninsular Malaysia alone, and its models suggested that hunting at that level could wipe out the local population within a few years. A flying fox gliding overhead at dusk is the closest real match for the ahool’s size and silhouette.[9]
The Javan owl matches the voice, the face and the behavior better. Its loud, deep hoot fits the onomatopoeic name better than any bat call. It lives in the same mid-mountain forest where Bartels was walking, and like many large owls it will swoop at people near a nest. It is also the kind of animal that rarely shows itself clearly: shy, nocturnal and seen mostly as a shape against the canopy. One possibility is that the ahool combines the two, a flying fox’s outline with an owl’s cry, merged in memory and retelling.[4][6]
Mount Salak today
Mount Salak is now protected as part of Gunung Halimun-Salak National Park, one of the largest remaining blocks of mountain rainforest on Java. It is home to the Javan gibbon, the Javan leopard and the Javan hawk-eagle, all endangered and all well studied by Indonesian and international researchers. Biologists, birdwatchers and camera traps have surveyed the park intensively. None has photographed or recorded a giant bat. An animal with a three-meter wingspan and a call loud enough to carry across a valley would be hard to miss in a forest watched this closely.
For another reported flying creature from Africa, see the Kongamato.
References
- Loren Coleman and Jerome Clark, Cryptozoology A to Z (New York: Fireside, 1999), p. 26.
- “Ahool,” Kook Science.
- George M. Eberhart, Mysterious Creatures: A Guide to Cryptozoology (Santa Barbara: ABC-Clio, 2002), p. 7.
- “Ahool,” archived Wikipedia article (2016), IPFS mirror.
- Karl P. N. Shuker, The Beasts That Hide From Man (New York: Paraview, 2003).
- Denver W. Holt et al., “Family Strigidae (Typical Owls),” in J. del Hoyo, A. Elliott and J. Sargatal (eds.), Handbook of the Birds of the World, vol. 5 (Barcelona: Lynx Edicions, 1999), 76–242.
- “Cerita Keturunan Bartels Saat Tumpukan Penelitian Dijarah Jepang,” detikJabar (January 2024), in Indonesian.
- “Bartels, Max Jr.,” Cyclopaedia of Malesian Collectors, Naturalis / Nationaal Herbarium Nederland.
- J. H. Epstein et al., “Pteropus vampyrus, a hunted migratory species with a multinational home-range and a need for regional management,” Journal of Applied Ecology 46 (2009): 991–1002; summarized in Scientific American.
Correction note (October 2026): This entry was rewritten from cryptozoological and zoological sources. An earlier version called Bartels a “Dutch zoologist” who only heard the creature in the early 1920s, and repeated claims of a scream audible for miles and a possible pterosaur identity without evidence. These have been corrected or removed. The illustration above is an artistic impression.