The common moorhen (Gallinula chloropus), also known as the waterhen, is a bird species in the rail family (Rallidae). It is distributed across many parts of the Old World, across Africa, Europe, and Asia.[1] It lives around well-vegetated marshes, ponds, canals and other wetlands.[1] The species is not found in the polar regions or many tropical rainforests; generally it is one of the commonest Old World rail species, together with the Eurasian coot in some regions.
The closely related common gallinuleG. galeata of the New World, and the tristan moorhenG. nesiotis and gough moorhenG. comeri of the Tristan da Cunha archipelago, formerly often regarded as conspecific, are now treated as a separate species by all the ornithological authorities,[6] following the discovery of significant genetic differences in addition to differences in the structure of the red bill shield and vocal differences.[7][8][9] The final species in the genus, the dusky moorhenG. tenebrosa of Australasia, has also been considered conspecific by some authors in the past.[10]
The name mor-hen has been recorded in English since the 13th century.[11] The word moor here is in its old sense meaning marsh;[11] the species is not usually found in what is now called moorland. Another old name, waterhen, is more descriptive of the bird's habitat.[11] 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 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. The subspeciesG. c. meridionalis is smaller than the nominate, has slaty blue-grey upperwing coverts and lacks the olive wash. Subspecies G. c. orientalis is similar to G. c. meridionalis but has a larger shield. Subspecies G. c. pyrrhorrhoa is darker than the nominate; subspecies G. c. pyrrhorrhoa has buff undertail coverts.[10] 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.[12] 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).[13][14]
Distribution and habitat
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, 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; these populations show high genetic diversity.[15]
Behaviour
Food and feeding
This species will consume a wide variety of vegetable material and small aquatic creatures. They forage beside or in the water, sometimes walking on lilypads or upending in the water to feed. They are often secretive, but can become tame in some areas. Despite loss of habitat in parts of its range, the common moorhen remains plentiful and widespread.
Breeding
The birds are territorial during breeding season, and will fight with other members of their species, as well as other water birds such as ducks, to drive them out of their territory. The nest is a basket built on the ground in dense vegetation. Laying starts in spring, between mid-March and mid-May in Northern hemisphere temperate regions. About 8 eggs are usually laid per female early in the season; a brood later in the year usually has only 5–8 or fewer eggs. Nests may be re-used by different females. Incubation lasts about three weeks. Both parents incubate and feed the young. These fledge after 40–50 days, become independent usually a few weeks thereafter, and may raise their first brood the next spring. When threatened, the young may cling to the parents' body, after which the adult birds fly away to safety, carrying their offspring with them.[12][16]
Status and population
On a global scale (all subspecies taken together) the common moorhen is as abundant, as its vernacular name implies. It is therefore considered a species of Least Concern by the IUCN.[1] However, small populations may be prone to extinction. The population of Palau, belonging to the widespread subspecies G. c. orientalis and locally known as debar (a generic term also used for ducks and meaning roughly "waterfowl"), is very rare, and apparently the birds are hunted by locals. Most of the population on the archipelago occurs on Angaur and Peleliu, while the species is probably already gone from Koror. In the Lake Ngardok wetlands of Babeldaob, a few dozen still occur, but the total number of common moorhens on Palau is about in the same region as the Guam population: fewer than 100 adult birds (usually fewer than 50) have been encountered in any survey.[17]
Other localised groups of common moorhen are starting to come under threat. The Royal Society for the Protection of Birds in the United Kingdom has the common moorhen classified as one of its 103 species whose conservation status is of moderate concern[18] due to its recent population decine. The number of breeding pairs has fallen to its lowest level in the UK since 1966[19] and has been protected under the Wildlife and Countryside Act (1981).
The common moorhen is one of the birds (the other is the Eurasian coot, Fulica atra) from which the cyclocoelidflatworm parasite Cyclocoelum mutabile was first described.[20] The bird is also parasitised by the moorhen fleaDasypsyllus gallinulae.[21]
Subspecies
Five subspecies are today considered valid; several more have been described that are now considered junior synonyms. Most are not very readily identifiable, as differences are subtle and often clinal. Usually, the location of a sighting is the most reliable indication as to subspecies identification, but the migratory tendencies of the species make identifications based on location not completely reliable. In addition to the extant subspecies listed below, an undescribed form from the Early Pleistocene is recorded from Dursunlu in Turkey.[22][23][24]
List of subspecies by date of description
Common and trinomial names
Description
Range
Eurasian common moorhen G. c. chloropus (Linnaeus, 1758) Includes G. c. correiana and G. c. indica.
Indo-Pacific common moorhen G. c. orientalis (Horsfield, 1821)
Small, with slate grey upperwing coverts and large frontal shield.
Found in the Seychelles, Andaman Islands, and South Malaysia through Indonesia; also found in the Philippines and Palau. The breeding population existing on Yap in Micronesia since the 1980s is probably of this subspecies, but might be of the rare G. c. guami.[25][26] Population size: Perhaps a few 100s on Palau as of the early 2000s,[17] less than 100 on Yap as of the early 2000s.[25][26]
African common moorhen G. c. meridionalis (C. L. Brehm, 1831)
Similar to G. c. orientalis, but the frontal shield is smaller.
^ abSnow, David W.; Perrins, Christopher M.; Doherty, Paul; Cramp, Stanley (1998). The Complete Birds of the Western Palaearctic on CD-ROM. Oxford University Press. ISBN0-19-268579-1.
^Ruan, L.; Xu, W.; Han, Y.; Zhu, C.; Guan, B.; Xu, C.; Goa, B.; Zhao, D. (2018). "Gene flow from multiple sources maintains high genetic diversity and stable population history of Common Moorhen Gallinula chloropus in China". Ibis. 160 (4): 855–869. doi:10.1111/ibi.12579.
^ abWiles, Gary J.; Johnson, Nathan C.; de Cruz, Justine B.; Dutson, Guy; Camacho, Vicente A.; Kepler, Angela Kay; Vice, Daniel S.; Garrett, Kimball L.; Kessler, Curt C.; Pratt, H. Douglas (2004). "New and Noteworthy Bird Records for Micronesia, 1986–2003". Micronesica. 37 (1): 69–96.