4-10-2015 VILLALONGA RESERVOIR, VALENCIA - EUROPEAN MOORHEN (JUVENILE) (Gallinula chloropus)

The common moorhen (Gallinula chloropus), also known as the waterhen or swamp chicken, is a bird species in the rail family (Rallidae). It is distributed across many parts of the Old World.

The common moorhen lives around well-vegetated marshes, ponds, canals and other wetlands. The species is not found in the polar regions or many tropical rainforests. Elsewhere it is likely the most common rail species, except for the Eurasian coot in some regions.

The closely related common gallinule of the New World has been recognized as a separate species by most authorities, starting with the American Ornithologists' Union and the International Ornithological Committee in 2011.

The name mor-hen has been recorded in English since the 13th century. The word moor here is an old sense meaning marsh; the species is not usually found in moorland. An older name, common waterhen, is more descriptive of the bird's habitat.

A "watercock" is not a male "waterhen" but the rail species Gallicrex cinerea, not closely related to the common moorhen. "Water rail" usually refers to Rallus aquaticus, again not closely related.

The scientific name Gallinula chloropus comes from the Latin Gallinula (a small hen or chicken) and the Greek chloropus (khloros χλωρός green or yellow, pous πούς foot).

The moorhen is a distinctive species, with predominantly black and brown plumage, with the exception of a white under-tail, white streaks on the flanks, yellow legs and a red frontal shield. The bill is red with a yellow tip. The young are browner and lack the red shield. The frontal shield of the adult has a rounded top and fairly parallel sides; the tailward margin of the red unfeathered area is a smooth waving line. In the related common gallinule (Gallinula galeata) of the Americas, the frontal shield has a fairly straight top and is less wide towards the bill, giving a marked indentation to the back margin of the red area.

The common moorhen gives a wide range of gargling calls and will emit loud hisses when threatened. A midsized to large rail, it can range from 30 to 38 cm (12 to 15 in) in length and span 50 to 62 cm (20 to 24 in) across the wings. The body mass of this species can range from 192 to 500 g (6.8 to 17.6 oz).

This is a common breeding and resident bird in marsh environments, rivers, well-vegetated lakes and even in city parks. Populations in areas where the waters freeze, such as eastern Europe, will migrate to more temperate climates. In China, common moorhen populations are largely resident south of the Yangtze River, whilst northern populations migrate in the winter, therefore these populations show high genetic diversity.