Mascarene teal

The Mascarene teal (Anas theodori), also known as the Mauritian duck and Sauzier's teal, is an extinct species of dabbling duck that lived on the Mascarene Islands of Mauritius and Réunion.

Mascarene teal
Illustrations of the sternum (11-12), coracoid (13), humerus (14-15), and tarsometatarsus (16-17) from the 1893 description
Conservation status
Extinct (1696)  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Anseriformes
Family:	Anatidae
Genus:	Anas
Species:	†A. theodori
Binomial name
†Anas theodori Newton & Gadow, 1893
Location of the Mascarene Islands where this species lived

Taxonomy

The related Madagascar teal

The reports of Bernardin and (1710) Boucher are puzzling insofar as that they mention both geese, sarcelles (teals, or ducks, which is this species) as well as canards (ducks, larger than sarcelles) as occurring or having occurred on Réunion. It is possible that a carpometacarpus bone apparently of an Aythya diving duck is referrable to these canards. If so, these birds were probably related to the Madagascar pochard, of which only small numbers are known to remain.^[2]

In 1889, the Mauritius government requested exploration of the Mare aux Songes swamp for "historical souvenirs", where vast amounts of dodo remains had earlier been found. The new excavations, under the direction of the French naturalist Théodore Sauzier [de], were successful, and apart from dodo bones, remains of other extinct animals, previously known as well as new species, were found. These bones were sent to the Cambridge Museum, where they were examined and described by the British ornithologist Edward Newton and the German ornithologist Hans Gadow. Based on a fragmentary sternum (breast bone), a pair of coracoids, eight humeri (upper arm bones), and a pair of tarsometatarsi (lower leg bones) in bad condition, they determined the existence of a duck differing from those of Madagascar while being similar to Meller's duck of that island, but smaller. They named it as a new species in the genus Anas, A. theodori, in honour of Sauzier.^[3]

Earlier, it was proposed that Meller's duck, also from Madagascar, is the closest living relative of A. theodori, but as more remains of the latter were unearthed this appears far less likely. Apart from a few, brief descriptions, not much is known about the bird in life, but its habits probably did not differ significantly from those of its close relatives. Bones have been found in the Mare aux Songes swamp on Mauritius and more recently on Réunion also.

In 1987, the British ornithologist Graham S. Cowles reported a hitherto undescribed skull of a duck from the Thirioux collection. As it differed from any other extant ducks from Mauritius, it was suggested to be the first known skull of the Mascarene teal.^[4]

Description

Illustration of a Dutch farm on Mauritius from 1670, which may show two Mascarene teals towards the top middle of the small, left stream

The Mascarene teal was a small duck, though larger than the Madagascar teal, its closest relative, and smaller than Meller's duck.^[5]

It was a small teal of the Anas gibberifrons superspecies of the Anas subgenus Nettion. Its closest relative is probably the Madagascar teal from Madagascar and, apart from having stronger wings and being considerably bigger (between a Sunda teal and a mallard in size), it seems to have looked very similar to that species.

In 2001, Cheke attempted to identify bird species on a 1670 illustration of a Dutch farm at Foul Bay, Mauritius, which showed agricultural practices and various animals. Cheke was primarily concerned with identifying a bird that had previously suggested to be a dodo, which he instead considered a Mauritius sheldgoose. The other birds were more enigmatic, but suggested two other waterbirds depicted in a stream could be cormorants pr ducks; he noted no visitors had mentioned living cormorants, while the Mascarene teal was still abundant at the time. Lastly, he identified a crow-like bird as a Mauritius bulbul.^[6][7]

Behaviour and ecology

The French palaeontologist Cécile Mourer-Chauviré and colleagues stated in 1999 that the proportions of the Mascarene teal's limb-bones were very similar to those of the Sunda teal, indicating no reduction in flight-capability, and were very different from those of flightless species like the Auckland teal (Anas aucklandica) and the Amsterdam wigeon (Anas marecula). It is therefore possible that the Mascarene teal had normal flight capabilities and was able to fly between Mauritius and Réunion, explaining how it occurred on both islands.^[2] Hume added in 2017 that it may also have moved seasonally.^[8][9] Cheke and Hume suggested in 2008 that, like the local starlings and parrots, the Mascarene teal possibly nested in tree-holes.^[10]

Life restoration of two Mascarene teals (lower right) and Réunion sheldgeese (left) by Julian P. Hume

The 1681 ship's log of the President mentioned gray teal on Mauritius, the only account that described its appearance:^[11]

Up a little within the woods are several ponds and lakes of water with great numbers of flamingoes and gray teal and geese; but for the geese these are most in the woods or dry ponds. No ducks on the island.^[10]

Cheke and Hume suggested in 2008 that "no ducks" was in reference to large, meaty ducks, unlike the small teal.^[10] The only contemporary mention of small anatids from Réunion is that of Sieur Dubois:

River ducks, smaller than European ones, feathered like teals. They are good [to eat]^[2]

Many other endemic species of Mauritius and Réunion were lost after the arrival of humans, so that the ecosystems of these islands are severely damaged and hard to reconstruct. Before humans arrived, the islands were entirely covered in forests, very little of which remains today, because of deforestation.^[12] The surviving endemic fauna is still seriously threatened.^[13] On Mauritius, the Mascarene teal lived alongside other recently extinct birds such as the dodo, the red rail, the broad-billed parrot, the Mauritius blue pigeon, the Mauritius scops owl, the Mauritian shelduck, and the Mauritius night heron. On Réunion, it lived alongside the Réunion ibis, the hoopoe starling, the Mascarene parrot, the local subspecies of the echo parakeet, the Réunion swamphen, the Réunion scops owl, the Réunion night heron, and the Réunion pink pigeon. The Mascarene coot and the Mascarene grey parakeet also lived on both islands.^[10]

Extinction

Travellers to Mauritius and Réunion made repeat mentions of highly palatable geese and ducks, and these were listed among the favourite prey of hunters there. Cheke stated in 1987 that the Mascarene teals were considered abundant in 1681, but quickly declined thereafter; the French explorer François Leguat considered them rare in 1693, and the Dutch governor of Mauritius Roelof Deodati declared them extinct in 1698. Cheke added that since the number of men on these islands was low in the 1600s, it is unlikely they would have been responsible for the extinction of widespread animals, but those limited to certain habitats, like for example ducks and geese, may have been exterminated by hunting, though reduced breeding would probably be due to introduced animals.^[11]

Cheke and Hume suggested in 2008 that the introduction of cats to Mauritius possibly in the 1680s led to a rapid decline in ground-nesting birds, and while the Mascarene teals may have nested in tree-holes, the ducklings would still have to walk from their trees to water. They pointed out that the last mention of "wild ducks" was from 1696 and "ducks" in 1706, but both probably referred to farmyard ducks.^[10] Hume and Walters stated in 2012 that since the 1681 President's log stated the teals existed in great numbers on Mauritius, they must have disappeared rapidly after that date, since they were not mentioned after 1700. They likewise existed in great numbers on Réunion, but were last mentioned a decade later. These authors listed overhunting to be the primary cause of extinction.^[8] Cheke elaborated in 2013 that the main culprit was cats, with hunting being secondary, and the species survived introduced rats and pigs.^[14]