The Olitiau Giant Bat Encounter, Assumbo Mountains (1932)

In 1932, Ivan T. Sanderson was about 21 years old. He was leading the Percy Sladen Expedition through the Mamfe Division of the British Cameroons, then a British mandate, collecting animals for science. With him was his friend Gerald Russell, a zoologist and animal collector. Sanderson would later become a writer and broadcaster. That year, he was a young naturalist in the forests north of Mamfe, near the Nigerian border.

One evening the two men were wading down a shallow river in the Assumbo Mountains. By one account they were looking for tortoises. By another they had stopped to retrieve a hammer-headed bat they had just shot.

Dusk. Still air over the water. Then Sanderson wrote what came next.

"Then I let out a shout also and instantly bobbed down under the water, because, coming straight at me only a few feet above the water was a black thing the size of an eagle."

As the account is usually given, its lower jaw was hanging open, "bearing a semicircle of pointed white teeth set about their own width apart from each other." Russell ducked too. The animal was jet-black, with gigantic wings "cutting through the still air with a loud hissing sound." The two men "fired a number of shots in the direction of this terrifying apparition." It got away. Sanderson saw it only briefly.

Back in camp, the local hunters heard what the men had seen. They gave it a name. The olitiau. Then they ran off in fear. The word is described as Ipulo, possibly a transcription of ole ntya, meaning "cloven" or "forked", the name of a horned dance mask that represents a demon.

Sanderson told the story in Animal Treasure, published in 1937 and later called a best-seller. He named the creature "the Granddaddy of all bats." In 1970 he consulted Russell again. Their written and remembered accounts matched. In later retellings both men put the wingspan at no less than 12 feet, and Sanderson said the face was flattened and monkey-like, not pointed like a dog's.

The obvious suspect was the hammer-headed bat, Africa's largest bat, and the very species the men had been shooting. Karl Shuker rejected it. The hammer-head's head is extremely long and swollen, nothing like the flat, monkey-like face Sanderson described. Advocates add that two collectors hunting that species would have recognised one. Other suggestions include the yellow-winged bat or an unknown large bat. A surviving pterosaur appears in later popular writing, though the witnesses never proposed it.

Size is part of the debate. The 1937 text says "the size of an eagle." The 12-foot wingspan arrives only in later retellings. Popular sources have since added red wings and 2-inch serrated teeth, details found nowhere in the witnesses' account.

No specimen, photograph or track was ever recovered. No one has accused Sanderson or Russell of inventing it. The olitiau became the foundational eyewitness report behind Africa's giant bat cryptids, usually discussed beside the kongamato of Zambia and the ahool of Java. Bernard Heuvelmans is among the writers linked to it, and Karl Shuker retold it in The Beasts That Hide From Man. The same expedition produced a second strange report, a large unknown water animal. But it is the black shape over the river that endures.