Moorhen
Encyclopedia
Moorhens, sometimes called marsh hens, are medium-sized water birds that are members of the rail family
Rallidae
. They constitute the genus
Gallinula.
They are close relatives of coot
s, and because of their apparently nervous behavior (frequently twitching tail, neck and grinding their backs) are sometimes called "skitty coots". Often, they are referred to as (black) gallinules.
A few species
from the Australia
n region, sometimes separated in Tribonyx, are called native-hens. Tribonyx is better considered a subgenus
however as the differences are not very striking and mainly plesiomorphic. The native-hens differ visually by shorter, thicker and stubbier toes and bills, and longer tails that lack the white signal pattern of typical moorhens.
colour. Unlike many of the rails they are usually easy to see, feeding 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 2,000 km 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 common in rails, there has been a marked tedency to evolve
flightlessness
in island populations.
Moorhens can walk very well on strong legs, and have long toes that are well adapted to soft uneven surfaces.
These birds are omnivorous taking plant material, small rodents, amphibians and egg
s. They are aggressively territorial during the breeding season, but are otherwise often found in sizeable flocks on the shallow vegetated lakes they prefer.
Living and recently extinct species
of Gallinula are:
Other moorhens have been described from older remains. Apart from the 1-3 extinctions in more recent times, another 1-4 species have gone extinct as a consequence of early human settlement: Hodgen's Waterhen (Gallinula hodgenorum) of New Zealand
—which belongs in subgenus
Tribonyx—and 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 Mangaia "swamphen," currently tentatively assigned to Porphyrio
, may belong to Gallinula/Pareudiastes.
s 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:
Even among non-Passeriformes, this genus has a long documented existence. Consequently some unassigned fragmentary rail fossils might also be from moor- or native-hens. For example, specimen QM
F30696, a left distal tibiotarsus
piece from the Oligo-Miocene boundary at Riversleigh
, is similar to but than and 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 (see also below).
In addition to paleosubspecies of Gallinula chloropus, the doubtfully distinct Late Pliocene to Pleistocene Gallinula mortierii reperta was described, referring to the population of the Tasmanian Native-hen
that once inhabited mainland Australia and became extinct at the end of the last ice age. It may be that apart from climate change
it was driven to extinction by the introduction of the dingo
, which as opposed to the marsupial
predators hunted during the day, but this would require a survival of mainland Gallinula mortierii to as late as about 1500 BC
G. disneyi was yet another flightless native-hen—indicative of that group's rather basal position among moorhens -, and its time and place of occurrence suggest it as an ancestor of G. mortierii (reperta), from which it differed mostly in its much smaller size. However, some limb bone proportions are also strikingly different, and in any case such a scenario would require a flightless bird to change but little during some 20 million years in an environment rich in predators. As the fossils of G. disneyi as well as the rich recent and subfossil
material of G. mortierii shows no evidence of such a change at all, G. disneyi more probably represents a case of parallel evolution
at an earlier date.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Rallidae
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...
. They constitute the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Gallinula.
They are close relatives of coot
Coot
Coots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...
s, and because of their apparently nervous behavior (frequently twitching tail, neck and grinding their backs) are sometimes called "skitty coots". Often, they are referred to as (black) gallinules.
A few species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
from the Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n region, sometimes separated in Tribonyx, are called native-hens. Tribonyx is better considered a subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
however as the differences are not very striking and mainly plesiomorphic. The native-hens differ visually by shorter, thicker and stubbier toes and bills, and longer tails that lack the white signal pattern of typical moorhens.
Description
These rails are mostly brown and black with some white markings in plumageFeather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
colour. Unlike many of the rails they are usually easy to see, feeding 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
Common Moorhen
The Common Moorhen is a bird in the Rallidae family with an almost worldwide distribution. The North and South American Committees of the AOU and the IOC have voted on or before July 2011 to split the American forms into a new species Common Gallinule, however, no other committee has voted to...
in particular migrates
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
up to 2,000 km from some of its breeding areas in the colder parts of Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
. 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 common in rails, there has been a marked tedency to evolve
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
flightlessness
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...
in island populations.
Moorhens can walk very well on strong legs, and have long toes that are well adapted to soft uneven surfaces.
These birds are omnivorous taking plant material, small rodents, amphibians and egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
s. They are aggressively territorial during the breeding season, but are otherwise often found in sizeable flocks on the shallow vegetated lakes they prefer.
Systematics and evolution
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of Gallinula are:
- Samoan Moorhen, Gallinula pacifica – sometimes placed in Pareudiastes, extinct (1907)?
- Makira MoorhenMakira MoorhenThe Makira Woodhen , also known as the Makira Moorhen, is a species of bird in the Rallidae family. It is endemic to Solomon Islands. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montanes.It is threatened by habitat loss.-References:*...
, Gallinula silvestris – sometimes placed in Pareudiastes or Edithornis, extinct (mid-20th century)? - Tristan MoorhenTristan MoorhenThe Tristan Moorhen is an extinct flightless rail from the South Atlantic island of Tristan da Cunha. It was physically similar to the Gough Island Moorhen of Gough Island, located 395 miles to the southeast....
, Gallinula nesiotis – extinct (late 19th century) - Gough Moorhen, Gallinula comeri
- Common MoorhenCommon MoorhenThe Common Moorhen is a bird in the Rallidae family with an almost worldwide distribution. The North and South American Committees of the AOU and the IOC have voted on or before July 2011 to split the American forms into a new species Common Gallinule, however, no other committee has voted to...
, Gallinula chloropus - Common GallinuleCommon GallinuleThe Common Gallinule, is a North American bird in the Rallidae family which has recently been split from the Common Moorhen by the AOU in July 2011. It lives around well-vegetated marshes, ponds, canals and other wetlands. The species is not found in the polar regions, or many tropical rainforests...
, Gallinula galeata, recently split by the AOU, other committees still evaluating - Dusky MoorhenDusky MoorhenThe Dusky Moorhen is a bird in the rail family. It occurs in Australia, New Guinea, and Indonesia.The New Guinea birds are smaller, at 25-32 cm in length, than the Australian race...
, Gallinula tenebrosa - Lesser MoorhenLesser MoorhenThe Lesser Moorhen is a species of bird in the Rallidae family.It is found in Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Egypt, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana,...
, Gallinula angulata - Spot-flanked GallinuleSpot-flanked GallinuleThe Spot-flanked Gallinule is a species of bird in the Rallidae family.It is found in Argentina, Bolivia, Brazil, Chile, Colombia, Paraguay, Peru, and Uruguay.Its natural habitats are swamps and freshwater lakes....
, Gallinula melanops - Black-tailed Nativehen, Gallinula ventralis
- Tasmanian Nativehen, Gallinula mortierii
Other moorhens have been described from older remains. Apart from the 1-3 extinctions in more recent times, another 1-4 species have gone extinct as a consequence of early human settlement: Hodgen's Waterhen (Gallinula hodgenorum) of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
—which belongs in subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
Tribonyx—and a species close to the Samoan Moorhen from Buka
Buka
Buka can refer to:* Buka, Papua New Guinea, the war capital of Bougainville Province.* Buka Island is the second largest island in the Papua New Guinean province of Bougainville.* Buka Entertainment, a computer game publisher...
, Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...
, which is almost certainly distinct from the Makira Moorhen
Makira Moorhen
The Makira Woodhen , also known as the Makira Moorhen, is a species of bird in the Rallidae family. It is endemic to Solomon Islands. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montanes.It is threatened by habitat loss.-References:*...
as the latter cannot fly. The undescribed Viti Levu Gallinule of Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
would either be separated in Pareudiastes if that genus is considered valid, or may be a completely new genus. Similarly, the undescribed Mangaia "swamphen," currently tentatively assigned to Porphyrio
Porphyrio
Porphyrio is the swamphen genus of birds in the rail family. It includes some smaller species which are usually called "purple gallinules", and which are sometimes separated as genus Porphyrula or united with the gallinules proper in Gallinula. There are two living species of swamphen, the...
, may belong to Gallinula/Pareudiastes.
Evolution
Still older fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s document the genus since the Late Oligocene onwards. The genus seems to have originated in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, in the general region of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. By the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
, it was probably distributed worldwide:
- Gallinula disneyi (Late Oligocene—Early Miocene of Riversleigh, Australia)
- Gallinula sp. (Early Pliocene of Hungary and Germany)
- Gallinula kansarum (Late Pliocene of Kansas, USA)
- Gallinula balcanica (Late Pliocene of Varshets, Bulgaria).
- Gallinula gigantea (Early Pleistocene of Czechia and Israel)
Even among non-Passeriformes, this genus has a long documented existence. Consequently some unassigned fragmentary rail fossils might also be from moor- or native-hens. For example, specimen QM
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
F30696, a left distal tibiotarsus
Tibiotarsus
The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia.A similar structure also occurred in the Mesozoic Heterodontosauridae...
piece from the Oligo-Miocene boundary at Riversleigh
Riversleigh
Riversleigh, in North West Queensland, is Australia's most famous fossil site. The 100 km² area has fossil remains of ancient mammals, birds and reptiles of Oligocene and Miocene age...
, is similar to but than and 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 (see also below).
In addition to paleosubspecies of Gallinula chloropus, the doubtfully distinct Late Pliocene to Pleistocene Gallinula mortierii reperta was described, referring to the population of the Tasmanian Native-hen
Tasmanian Native-hen
The Tasmanian Nativehen is a flightless rail and one of twelve species of birds endemic to the Australian island of Tasmania...
that once inhabited mainland Australia and became extinct at the end of the last ice age. It may be that apart from climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
it was driven to extinction by the introduction of the dingo
Dingo
The Australian Dingo or Warrigal is a free-roaming wild dog unique to the continent of Australia, mainly found in the outback. Its original ancestors are thought to have arrived with humans from southeast Asia thousands of years ago, when dogs were still relatively undomesticated and closer to...
, which as opposed to the marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
predators hunted during the day, but this would require a survival of mainland Gallinula mortierii to as late as about 1500 BC
G. disneyi was yet another flightless native-hen—indicative of that group's rather basal position among moorhens -, and its time and place of occurrence suggest it as an ancestor of G. mortierii (reperta), from which it differed mostly in its much smaller size. However, some limb bone proportions are also strikingly different, and in any case such a scenario would require a flightless bird to change but little during some 20 million years in an environment rich in predators. As the fossils of G. disneyi as well as the rich recent and subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
material of G. mortierii shows no evidence of such a change at all, G. disneyi more probably represents a case of parallel evolution
Parallel evolution
Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.-Parallel vs...
at an earlier date.