Sasa

According to the locals of Viti Levu, the largest island in Fiji, and the eighth largest in Oceania, an unknown megapode bird exists in the tropical rainforests called the sasa. Megapodes are birds in the Megapodiidae family, which are medium-sized to large terrestrial, turkey-like birds native to Southeast Asia and Oceania, though no species are thought to live in Fiji and other outer Melanesian archipelagos. 

According to reports, the sasa is the size of a chicken, with brown feathers and speckled dots of grey. Sasas build small mounds to incubate their eggs to protect them from lizards, birds of prey, and even humans. Some have theorized the sasa is a misidentified scrub hen, but they are only native to the rainforests on the east coast of Australia. In the 1926 book A Collection of Birds from the Fiji Islands, Part III: Field Observations, the sasa has a page dedicated to it as many other birds do, suggesting they're not exactly rare, and the illustration clearly shows it's not a scrub hen. Few sightings of the sasa persist into modern times, so its numbers may have shortened from overhunting or the introduction of cats. 

In 1970, ornithologist A. Blackburn did a survey of bird species in the remote Nausori Highlands, as well as various other scattered outer islands. On September 10th, 1970, two members of one of Blackburn's search party saw a strange bird, resembling a megapode, on a creekbed south of Gasele, on Kadavu Island. The bird, which had long legs, short tail, and broad, rounded wings, awkwardly glided down from a tree. When the bird noticed the surveyors, it "gave a startled squawk" and fled into a patch of cane grass. This sighting was featured in Blackburn's 1971 journal Some Notes on Fijian Birds. Blackburn also mentions two mounted specimens of megapodes found in Niuafo'ou Island, Tonga that was kept in the Auckland Museum, though they seem to be lost.

If the sasa is a real animal, it is likely a small surviving population of the Viti Levu scrubfowl (Megapodius alimentum), an obscure species of recently discovered extinct megapode that died out in the late Pleistocene or early Holocene. If the sasa was discovered, it would become the only known species of extant megapode native to Fiji.