Moriglione del Madagascar

Identificazione

The pochard is a medium-sized duck between 42 and 56 centimeters in size. Juvenile ducks have brown irises and are a pale, dull brown or chestnut color with a darker stomach. The adults are darker in color, though during a male duck's first winter, its iris will turn white. Breeding males have dark chestnut heads, chins, throats, breasts, and necks, with blackish brown on the top side of the body. Their wings are dark brown with a white bar. The area under the bodies from the stomach to the tail fades to white, as do the undersides of the wings. The beaks and legs are dark grey with black nails.<p>Vocalizations may include "[when] in display [...] the male utters a cat-like wee-oow and a rolling rrr, while the female gives a harsh squak."

Tassonomia

The Madagascar pochard was largely overlooked by scientists in the 19th century, as those that saw it assumed they were seeing ferruginous ducks instead. Even after its description in 1894 little notice was taken of the species, and even numbers are hard to gauge from early accounts of the species. Based on the accounts written by Webb and Delacour's in the 1920s and 1930s it seemed that the bird was still relatively common at Lake Alaotra.<p>The Madagascar pochard is generally thought to be closely related to the Hardhead, Baer's pochard and ferruginous duck. It is monotypic, having no described or known subspecies.

Nome scientifico

Aythya innotata

Autorità

(Salvadori, 1894)

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Aythya

Areale e habitat

The species exclusively lives in inland wetlands in Madagascar, where it is endemic. Currently, the only wild populations are at Lake Sofia and Lake Matsaborimena.<p>Historically, the birds preferred shallow lakes and marshes with dense vegetation; however, the rediscovered population was found in a cold, deep crater lake that had few aquatic plants and was surrounded by heavy forest, and other remote crater lakes may have been inhabitable due to the birds' requirements for shallower water. Its previous habitat in the Lake Alaotra basin was disturbed by rice cultivation and invasive introduced fishes.

Migrazione

Resident species

Comportamento

Madagascar pochards do not migrate, do not usually form flocks, and are usually found in pairs or as single ducks.<p>The Madagascar pochard spends 38% of its day feeding. The diet is dominated by aquatic insects; a study examining their faeces found that caddisflies were the most commonly found insect, followed by dragonfly larvae, bugs (Hemiptera) and flies from the family Chironomidae. Stable isotope analysis and the faecal studies have shown that their diet includes very little plant material, which is unusual when compared to their relatives in the genus Aythya.<p>The bird dives for much of its food, with a mean diving time of around 24 seconds. Ducklings feed on the surface until they are old enough to dive, at around 14 days, and make shorter dives once they do dive (around 10 seconds).<p>Observers have noted nesting behavior from July to February, sometimes with multiple attempts at nesting. Nests are found 20–40 cm above water, in the plants along the lake or marsh edges (noted in Cyperaceae), with 6 to 10 eggs per clutch.

Conservazione

Tendenza della popolazione

stable