Moorhen

Moorhens are medium-sized water birds in the genus Gallinula, Latin for 'little hen', in the rail family Rallidae. The genus currently includes seven species, of which one is extinct, and two others probably are. Three species formerly included in Gallinula have been found to have enough differences to be placed in two separate but closely related genera, Paragallinula, and Tribonyx, the two native hens of Australia; Tribonyx differs visually by shorter, thicker and stubbier toes and bills, and longer tails that lack the white signal pattern of typical moorhens. The moorhens are also close relatives of the coots, but the swamphens, formerly also thought to be close relatives, are now known to be less closely related.

Description

These rails are dumpy, compact birds with mostly brown and black with some white markings in their plumage; they range from 25–40 cm long. The bills are red, mostly with a yellow tip, and the legs are yellowish-green to yellowish-orange; the toes are long, but not webbed, nor lobed as in coots. Unlike many of the rails, they are usually easy to see because they feed in open water margins rather than hidden in reedbeds.
They have short rounded wings and are weak fliers, although usually capable of covering long distances. The common moorhen in particular migrates up to from some of its breeding areas in the colder parts of Siberia. Those that migrate do so at night. The Gough moorhen on the other hand is considered almost flightless; it can only flutter some metres. As is common in rails, there has been a marked tendency to evolve flightlessness in island populations.
Moorhens can walk well on their strong legs, and the long toes are well adapted to soft uneven surfaces. They can swim well, despite the lack of webs on the toes.
These birds are omnivorous, consuming plant material, small rodents, amphibians and eggs. They are aggressively territorial during the breeding season, but are otherwise often found in flocks on the shallow vegetated lakes they prefer.

Systematics and evolution

The genus Gallinula was introduced by the French zoologist Mathurin Jacques Brisson in 1760 with the common moorhen as the type species.

Species

The genus contains five extant, one recently extinct, and two possibly extinct species.

Image	Common name	Scientific name	Distribution and notes
	Dusky moorhen	Gallinula tenebrosa Gould, 1846	Australia, New Guinea, southeastern Indonesia, New Caledonia
	Common gallinule	Gallinula galeata	Americas, including Bermuda, Galápagos, and Hawaii
	Common moorhen	Gallinula chloropus	Europe, Asia, Africa, Macaronesia; widespread
	†Tristan moorhen	Gallinula nesiotis P. L. Sclater, 1861	Tristan da Cunha, extinct
	Gough moorhen	Gallinula comeri J. A. Allen, 1892	Gough Island off Tristan da Cunha. Introduced on Tristan da Cunha as ecological replacement for extinct G. nesiotis. Formerly sometimes placed in Porphyriornis.
	Makira woodhen	Gallinula silvestris	Makira, extremely rare with no direct observations in recent decades, but still considered likely extant due to reports of the species persisting in small numbers. Sometimes placed in Pareudiastes or Edithornis.
	Samoan woodhen	Gallinula pacifica	Samoa, possibly extinct. Sometimes placed in Pareudiastes.

Species formerly included in the genus:

Lesser moorhen Paragallinula angulata
Black-tailed nativehen Tribonyx ventralis
Tasmanian nativehen Tribonyx mortierii

Other moorhens have been described from older remains. Apart from the 1–2 extinctions in more recent times, another 1–4 species have become extinct as a consequence of early human settlement; a species close to the Samoan moorhen from Buka, Solomon Islands, which is almost certainly distinct from the Makira moorhen, as the latter cannot fly. The undescribed Viti Levu gallinule of Fiji would either be separated in Pareudiastes if that genus is considered valid, or may be a completely new genus. Similarly, the undescribed "swamphen" of Mangaia, currently tentatively assigned to Porphyrio, may belong to Gallinula or Pareudiastes.

Evolution

Still older fossils document the genus since the Late Oligocene onwards. The genus seems to have originated in the Southern Hemisphere, in the general region of Australia. By the Pliocene, it was probably distributed worldwide:

Gallinula sp.
Gallinula kansarum
Gallinula balcanica.
Gallinula gigantea

The ancient "Gallinula" disneyi has been separated as genus Australlus.
Even among non-Passeriformes, this genus has a long documented existence. Consequently, some unassigned fragmentary rail fossils might also be from moorhens or native hens. For example, specimen QM F30696, a left distal tibiotarsus piece from the Oligo-Miocene boundary at Riversleigh, is similar to but differs in details from "G." disneyi. It cannot be said if this bird—if a distinct species—was flightless. From size alone, it might have been an ancestor of G. mortierii.