Sunday, 10 April 2016

The extinct Dodo that never even existed

Everyone has heard of the Dodo — that large, flightless relative of the pigeons that was found only on the Indian Ocean island of Mauritius and became extinct in the 17th century. 

Known to science as Raphus cucullatus, this docile and inquisitive bird was first recorded by Dutch sailors in 1598. Because of subsequent hunting and habitat destruction, along with predation by mammals introduced by man, numbers rapidly dwindled and the last widely accepted sighting of a Dodo was in 1662. Although there were some possible later encounters, it is generally agreed that the species was fully extinct by the end of the 17th century. 

Yes, everyone is aware of the Dodo. But few people have heard of a close relative from the volcanic island of Réunion, which lies 225km (140 miles) west of Mauritius. This bird, the Réunion Solitaire (Raphus solitarius), has a unique feature — not only is it also officially extinct, but it seems never to have existed in the first place! It was, however, accepted as a second species of Dodo until as recently as the 1980s, and it still appears in some official lists of extinct birds and is described on a number of websites. 

Image of a Réunion Solitaire, based
on 17th century written accounts
 The Réunion Solitaire is known only from old written descriptions and pictorial records. Travellers' accounts from the 17th century describe a large white bird that could fly only with difficulty. One account specifically referred to it as a Dodo. It is perhaps not surprising that illustrators in Europe who had not seen the bird for themselves produced images depicting it as a white variant on the better known Mauritian species. 

Réunion’s “Dodo” was given the name Solitaire because it seemed to prefer the solitude of the mountains — although it is quite possible that the bird had only become confined to mountainous areas because of heavy hunting by man and predation by animals that man had introduced. 
Hypothetical restoration of the Réunion
Ibis, based on subfossil remains, 17th
century written accounts and extant
relatives in the same genus

Records indicate that the Réunion Solitaire was driven to extinction by the early 18th century. However, no remains of a Dodo-like bird have ever been found on Réunion, and it is now generally accepted that the solitaire was not even closely related to the Dodo. Since 1974, subfossils of an extinct ibis have been unearthed on Réunion, and it appears that this bird was the real solitaire. The Réunion Ibis was first scientifically described in 1987 and was given the specific name Threskiornis solitarius. Its closest extant relatives are the African Sacred Ibis (T aethiopicus) and the Malagasy Sacred Ibis (T bernieri).

Although Réunion never had its own Dodo, the Mauritian species did at least have one genuine cousin. This bird lived on Rodrigues, the last of the three major volcanic islands in the Mascarene Archipelago, some 620km (385 miles) east of Mauritius. The Rodrigues Solitaire was described and drawn by François Leguat, leader of a group of French Huguenot refugees who were marooned on the island from 1691 to 1693. Like the Mauritian Dodo and the Réunion Ibis, this bird also fell foul of human hunters and introduced mammals. It probably became extinct some time between the 1730s and 1760s.

François Leguat’s drawing of the 
Rodrigues Solitaire — the only 
known drawing by someone 
who observed the bird in life
Apart from a handful of other contemporary descriptions, including Leguat’s detailed account and drawing, nothing was known about the Rodrigues Solitaire until a few subfossil bones were found in a cave in 1789. Since then, thousands of bones have been excavated. They have allowed taxonomists to decide that the bird was certainly a near relative of the Dodo. However, it was not close enough to be placed in the Raphus genus and it was given its own genus, Pezophaps (meaning “pedestrian pigeon”). But Raphus cucullatus and Pezophaps solitaria are close enough to share an extinct subfamily, the Raphinae, within the large pigeon family, the Columbidae.

The Columbidae family features about 310 species. Sadly, the Dodo and the Rodrigues Solitaire are among no fewer than 10 family members to become extinct since 1600, which is the conventional date used for estimating “modern” extinctions.

No comments:

Post a Comment