A mysterious bird in our LOST ZOO, the Réunion sacred ibis

Since more than 300 years the existence of the Réunion sacred ibis (Threskiornis solitarius) was forgotten and believed to be extinct, but in 1974 first signs of its existence were found on Réunion and almost unbelievable, today this extraordinary bird lives in our Lost Zoo.

Old paintings of Réunion ibis①(Click to view larger image).

As the name mentions, this ibis species is endemic to the volcanic island of Réunion in the Indian Ocean. Its closest relatives are the Malagasy sacred ibis and the African sacred ibis.

Already in the 17th and 18th century, travelers describe a bird living in the mountainous areas of Réunion, which is about 65 cm in length, mainly white, but also merging into yellow and grey. Its wing tips and the ostrich-like feathers on its rear are black. The neck and legs are long and the beak is relatively straight and rather short for an ibis. In general the bird looks quite similar to an ibis, but it is stockier in body shape than other ibis relatives and has reduced flight capabilities. This could be the reason for seasonal fattening.

Because this white bird flew with difficulty and preferred solitude, it was subsequently referred to as the Réunion solitaire which would be a white relative of the well-known grey dodo of neighboring Mauritius. In the 17th century some Dutch paintings of a white dodo supported this idea and since the mid 19th century scientists believed that besides the Dodo (Raphus cucullatus) on Mauritius and the Rodrigues solitaire (Pezophaps solitaria) on Rodrigues Island a third species, the White dodo, would exist on Réunion Island. This opinion has been accepted by ornithologists for almost two centuries.

However, no fossils referable to dodo-like birds were ever found on Réunion. Therefore it was later questioned whether the paintings had anything to do with the island. Also the better knowledge about the volcanic geology of the Réunion Island aroused doubts about the existence of a dodo species on this island. In 1974 the discovery of a subfossil ibis led to the idea that the old accounts actually referred to an ibis species instead. Its wing-bones indicate that it had reduced flight capabilities, a feature perhaps linked to seasonal fattening. The diet of the Réunion ibis consists of worms and other items foraged from soil. In 1987 this ibis was first scientifically described and the idea that the Réunion solitaire and the subfossil ibis are identical is today widely accepted and the ibis is scientifically named now as Réunion sacred ibis (Threskiornis solitarius).

When Réunion was populated by settlers, the Réunion sacred ibis appears to have become confined to the remote tops of mountains because of heavy hunting by humans and predation by introduced cats and pigs in the island’s more accessible areas. These factors are believed to have driven the Réunion sacred ibis to extinction by the early 18th century. The last account of the "solitaire" of Réunion was in 1708. It is thought to have been driven to extinction around 1710–1715. – But 300 years later, this rare bird is now kept in our LOST ZOO.

Executive Curator
JURGEN LANGE