Chevalier des Touamotou

Chevalier des Touamotou
Classification classique
Règne	Animalia
Embranchement	Chordata
Sous-embr.	Vertebrata
Classe	Aves
Ordre	Ciconiiformes
Famille	Scolopacidae
Genre	Prosobonia
Nom binominal
Prosobonia cancellata J.F. Gmelin, 1789
Statut de conservation IUCN : EN  : En danger
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Le Chevalier des Touamotou est une espèce menacée de limicole de la famille des Scolopacidae endémique des îles de l'archipel des Tuamotu en Polynésie française. Il se nomme kivi-kivi dans la langue indigène. L'une des plus importantes colonies se trouve sur l'atoll Morane.

Sommaire 1 Synonymes 2 Description 3 Distribution 4 Mœurs 5 Statut 6 Taxonomie 7 Liens externes

Synonymes

• Aechmorhynchus cancellatus
• Aechmorhynchus parvirostris
• Tringa cancellatus
• Tringa cancellata
• Tringa parvirostris

Description

Le Chevalier des Touamotou est un petit limicole (15,5 à 16.5 cm de long) à ailes courtes. Son plumage est brun moucheté avec les parties inférieures plus ou moins barrées. Son court bec pointu ressemble davantage à celui d'un passereau insectivore qu'à celui d'un limicole.

Cet oiseau présente deux phases de coloration et des intermédiaires. Les oiseaux pâles sont brun moyen dessus et blancs dessous avec des barres et des taches claires sur la poitrine et des stries blanchâtres sur la tête.

The bold supercilium and the chin are also white. The rectrices are brown with white tips and white triangular markings on the outer webs. Dark phase birds replace medium with darker brown and white with light buff or tawny white. The flanks are brown, and the entire underparts are heavily barred that color.

Ses iris sont bruns, son bec noirâtre, ses pattes et ses pieds de jaune sale à brun olive sombre. Ses doigts ne sont pas palmés.

Cette espèce ne présente pas de dimorphisme sexuel.

The former having a tendency to be slightly larger and paler on average.

Distribution

L'espèce est recensée aujourd'hui dans plusieurs atolls de la Polynésie, du nord-ouest au sud-est :

• Rangiroa, Niau, Kauehi et Fakarava dans les Îles Palliser ;
• Raraka, Katiu, Tahanea, Tuanake, Hiti and Tepoto Sud (Ofiti) dans les Îles Raevski ;
• Puka-Puka dans les Îles du Désappointement ;
• Anuanuraro dans les Îles du Duc de Gloucester ;
• Nukutavake et Pinaki, entre les Îles Revski et le Groupe Actéon ;
• Tenararo, Vahanga, Tenarunga, Matureivavao, Marutea Sud et Maria dans le Groupe Actéon ;
• Morane, au sud du Groupe Actéon ; et
• Makaroa, Kamaka et Manui dans les Îles Gambier.

Mœurs

This bird lives on undisturbed atolls where it feeds in open areas, including the shores and beaches, and scrubland; it is more rarely found in Pandanus thickets. It takes insects such as ants, leafhoppers and wasps in the coral rubble and leaf litter, also taking some vegetation.

The call is a soft, high whistle or piping, transcribed as meh by the Whitney South Seas Expedition.

It breeds at different times on different islands, generally between April and June. Nests are placed on the lagoon shore and consist of nothing more than a slight hollow in the shoreline coral and shell debris which is lined with grass stems or similar vegetable matter. The clutch is believed to be two eggs, which are white with purple and violet blotches, similar to a smaller version of the Upland Sandpiper's eggs. One two-egg clutch is in the American Museum of Natural History collection (specimen AMNH 5299).

Statut

The Tuamotu Sandpiper is threatened by introduced rats and habitat destruction caused by the spreading cultivation of coconuts, and is listed as endangered. Although it had a much wider range historically (see also below), it now survives on a small number of rat-free islands, namely Anuanuraro, Tenararo, Morane and one other atoll. Birds will occur as non-breeding visitors on other islands nearby, particularly in the Acteon group.

Its IUCN Red List status of Endangered B1a+b (ii, iii, iv, v); Vulnerable C2a(i), D1 means that estimates indicate between 250 and 1000 mature birds occurring in less than 6 locations, with a declining trend[1]. There are no conservation measures in place, although proposals are being suggested to protect the species. These include granting full protection to the remaining atolls where it breeds and preventing the further spread of rats.

Taxonomie

Historically, the species occurred also on Kiritimati (Christmas) Island in Kiribati (the type locality) and possibly others. John Latham figured the bird as the "Barred Phalarope" in his General Synopsis of Birds, based on a Kiritimati specimen collected on Captain Cook's last voyage, probably on 1er janvier or 2, 1778. This was in the collection of Joseph Banks at Latham's time, but later became lost. During Cook's visit, the bird was observed by William Anderson and painted by William Ellis (linked below).

Latham's description was the basis for Gmelin's, which was valid according to zoological nomenclature. The Tuamotu birds only came to the attention of science during the US Exploring Expedition, which collected 5 specimens in late August, 1839. These were described by Titian Peale as species parvirostris based on perceived differences to Latham's description. The validity of this form is in doubt; some considered it distinct, whereas in recent times the evidence is generally found too scant to consider both forms good species.

However, it is entirely likely that (given the non-migrant nature of the species) the populations, some 2000 miles separated from each other, would consititute separate subspecies. In this case, the Tuamotu subspecies would be called Prosobonia cancellata parvirostris, while the Kiribati population would be the nominate subspecies, P. c. cancellata (Kiritimati Sandpiper). The Kiritimati population is extinct since some time in the first half of the 19th century or possibly later due to introduced predators. These might have been Black Rats (Rattus rattus); as these were only temporarily present on Kiritimati and perhaps did not arrive until the 20th century, the feral cats which started to overrun the island in the 19th century make more likely culprits.

Liens externes

• ARKive - Images et documents sur le chevalier des Touamotou (Prosobonia cancellata)
• Référence Alan P. Peterson : Aechmorhynchus cancellatus dans Ciconiiformes (en)
• Référence Avibase : Aechmorhynchus cancellatus (+répartition) (fr+en)
• Référence Catalogue of Life : Tringa cancellatus (en)
• Référence Catalogue of Life : Prosobonia cancellata (J. F. Gmelin, 1789) (en)
• Référence ITIS : Tringa cancellatus (fr) (+version (en))
• Référence ITIS : Prosobonia cancellata (J. F. Gmelin, 1789) (fr) (+version (en))
• Référence Animal Diversity Web : Tringa cancellatus (en)
• Référence Animal Diversity Web : Aechmorhynchus cancellatus (en)
• Référence Animal Diversity Web : Prosobonia cancellata (en)
• Référence IUCN : espèce Prosobonia cancellata (Gmelin, 1789) (en)
• Référence Fonds documentaire ARKive : Prosobonia cancellata (en)

• Portail de l’ornithologie