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.

Return of the crane

During a recent short break in Cambridgeshire, my wife and I visited a wetland nature reserve. As soon as we reached the car park overlooking the site I noticed two large birds flying across the reserve towards us. As I scrabbled for my binocular they dropped down into the wet grassland about 200 metres away. But even before I could train my lenses on them, I realised to my delight that they were cranes — the first I have ever seen in Britain. 

Common Cranes in Cambridgeshire

While I was trying to photograph the distant birds, I met a binocular-toting dog-walker and asked her if cranes were regular visitors to the reserve. She told me that a pair had successfully bred a few years ago and then stayed on, sometimes joined by a few other birds. 

(I will not identity the site, since I suspect that the conservation organisation responsible for it does not want publicity. There is certainly no mention of cranes on the reserve’s website pages.)

The by-no-means-common Common Crane (Grus grus) is mainly a long-distance migrant, breeding across northern Europe and Asia and predominantly wintering in northern Africa. It is one of Britain’s rarest birds, normally encountered only as a scarce passage migrant in spring and autumn. 

The Common Crane bred in Britain in the Middle Ages, but land drainage and hunting led to its disappearance as a breeding bird by the start of the 17th century. But then in autumn 1979 two birds appeared in Norfolk at Hickling Broad and stayed on rather than continuing south. Three years later they raised a single chick — the first successful breeding in Britain for about 400 years. Over the following few years, they made further breeding attempts. Other birds stopped off from their migration to join them and a few of them also stayed on. And Hickling Broad now has a resident flock of about 20 birds, with two or three pairs breeding successfully each year. 

This natural success in Norfolk stimulated a scheme called the Great Crane Project, in which the Wildfowl and Wetlands Trust, the Royal Society for the Protection of Birds and the Pensthorpe Conservation Trust have sunk hundreds of thousands of pounds into persuading hand-reared cranes to breed in the Somerset Levels. The RSPB alone currently has a target of raising £1.5 million for this dubious project (see 
According to the RSPB website, the rationale for this horrendously costly scheme is that the small Norfolk Broads population “remains isolated” and cranes therefore “need a big helping hand” to recolonise their other former wetland haunts. But does the Norfolk population really “remain isolated”? And do cranes really need an extravagant “helping hand” elsewhere? 

Without any expensive hand-rearing, cranes began breeding at the RSPB’s Lakenheath Fen reserve in Suffolk a few years ago, and they have also bred on Humberside and in north-east Scotland, as well as at the Cambridgeshire reserve where I saw them. There is no reason why they should not naturally continue to spread into other wetland areas across Britain without the “helping hand” of the Great Crane Project. The money splurged on this profligate scheme could surely be used more effectively elsewhere.

Wednesday, 6 April 2016

On not hearing the first cuckoo in spring

For centuries, the call of the Cuckoo has been considered a harbinger of spring. The bird’s arrival was once so keenly awaited that April 14 was designated Cuckoo Day because the first Cuckoo was usually heard on or about that day in southern England. 

According to an old verse, the Cuckoo sings from St Tiburtius Day to St John's Day — ie, from Cuckoo Day, which is also the feast day of St Tibertius (a Christian martyr in ancient Rome), to June 24, which is Midsummer Day and the feast day of St John the Baptist. 

Why the June 24 cut-off? Since the Cuckoo is a brood parasite — relying on other birds to raise its young — it has no breeding territory to defend and so has no need to continue singing further into the summer. 

But today the call of the Cuckoo is far from common. The species has been in decline for 50 years or so, and since the early 1980s its population has dropped by two-thirds. In 2009 it was added to the UK red list of Birds of Conservation Concern. 

The reasons for the Cuckoo’s decline are not known. Some people have blamed it on the destruction of the habitat of the small birds that find themselves fostering young Cuckoos. However, this is unlikely because none of the main host species — the Meadow Pipit, the Dunnock, the Reed Warbler and the Pied Wagtail — is also in significant decline. 

Another possible cause is an increased use of pesticides on farmland. This may have reduced the numbers of caterpillars, which are the Cuckoo’s main prey. But other birds that feed mainly on caterpillars have not shown such a sharp decline. 

Climate change has also been suggested as a factor. Global warming has certainly shifted forward the host birds’ breeding by a few days, but there is no evidence of any link to the Cuckoo’s decline. 

With no specific evidence of problems in the bird’s summer haunts, we should perhaps be looking elsewhere. Major causes of decline may be the deterioration of conditions along the Cuckoo’s migration routes and problems within its over-wintering grounds in sub-Saharan Africa.