Tasmanian Native-hen
Encyclopedia
The Tasmanian Nativehen (Gallinula mortierii) is a flightless rail
and one of twelve species of birds endemic to the Australia
n island of Tasmania
. Although many flightless birds have a history of extinction
at the hands of man, the Tasmanian Nativehen has actually benefited from the introduction of European style agricultural practices in Tasmania.
.
The Tasmanian Nativehen is a stocky flightless bird between 43 and 51 cm (16.9 and 20.1 in) in length. The upperparts are olive brown with a white patch on the flank. The underparts are darker with a bluish grey tinge. The short tail is close to black and mostly held erect. The legs are thick and powerful, with a grey scaly appearance and sharp claws. The eyes are bright red. The bill has a small frontal shield and is a greenish yellow colour.
The juvenile bird is similar in appearance to the adult, but the colours are more subdued on the body and the underparts have fine white spots. The bill is greenish yellow and the eyes are bright red. Male birds generally have longer bills and legs, though there is enough overlap that the sexes are indistinguishable, even in the hand.
, though Michael Sharland does record it as being on Flinders Island. A population introduced to Maria Island
is now well established. It is generally common and easily seen around bodies of water that have grassy verges.
Fossil records indicate that the Tasmanian Nativehen was found on the Australian mainland until around 4700 years ago. Suggested reasons for its extinction there have included the introduction of the dingo
, or an extremely dry period.
The breeding structure may be monogamous or polygamous, usually polyandrous. Each group contains a single breeding female who will mate with all the males of the group. The unusual social structure based on groups who stay together is not known to occur in many other species; the high ratio of male chicks to female chicks hatched is thought to be a possible explanation for this.
The Tasmanian Nativehen has 14 separate calls, ranging from low grunts to high pitched alarm calls as well as a see-sawing duet performed in unison, rising to a crescendo of harsh screeching notes, It also calls at night.
Although flightless, this bird is capable of running quickly and has been recorded running at speeds up to 48 kilometres per hour (29.8 mph), It uses its wings when running fast to help it to balance.
The Tasmanian Nativehen is a secondary grazer, meaning that it depends on other species to keep grass swards low and with fresh shoots. Before European settlement in Tasmania, the cleared spaces required for feeding would probably have been provided by Indigenous burning of grasslands to provide feeding grounds for mammals, which would be hunted for food. The expansion of these cleared grassy areas, and the introduction of rabbits, has provided greater food sources and consequently greater numbers of the species within its range.
to Tasmania and the possible impact that it will have on this and other species.
As of 15 August 2007, the Tasmanian Nativehen was listed as protected under Tasmanian legislation. Prior to this the Tasmanian Nativehen was one of only four native birds that had no legal protection outside national parks and other reserves in the state of Tasmania—the last of Tasmania's 12 endemic bird species with this dubious status. The three remaining unprotected native species are the Forest Raven
, the Great Cormorant
, and the Little Pied Cormorant
. All other native Tasmanian birds are listed as protected under the state's Nature Conservation Act 2002.
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...
and one of twelve species of birds endemic to 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 island of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. Although many flightless birds have a history of extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
at the hands of man, the Tasmanian Nativehen has actually benefited from the introduction of European style agricultural practices in Tasmania.
Nomenclature
Other common names include Narkie, Native-hen, Waterhen and Turbo chook. This species was originally described in 1840 as Tribonyx mortierii. The name mortierii is in honour of Barthélemy Charles Joseph DumortierBarthélemy Charles Joseph Dumortier
Barthélemy Charles Joseph, Baron Dumortier was a Belgian politician and botanist. Some consider him to be the true discoverer of cell division, although he is rarely credited as such.-Works:...
.
Description
The juvenile bird is similar in appearance to the adult, but the colours are more subdued on the body and the underparts have fine white spots. The bill is greenish yellow and the eyes are bright red. Male birds generally have longer bills and legs, though there is enough overlap that the sexes are indistinguishable, even in the hand.
Habitat and distribution
The Tasmanian Nativehen is a sedentary species, living around open grassy areas close to water. It is widespread in Tasmania apart from the west and south west regions. It is not found on King or Flinders Islands in Bass StraitBass Strait
Bass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...
, though Michael Sharland does record it as being on Flinders Island. A population introduced to Maria Island
Maria Island
Maria Island is a mountainous island off the east coast of Tasmania. The entire island is a national park. Maria Island National Park has a total area of 115.50 km², which includes a marine area of 18.78 km² off the island's northwest coast. The island is about 20 km in length from...
is now well established. It is generally common and easily seen around bodies of water that have grassy verges.
Fossil records indicate that the Tasmanian Nativehen was found on the Australian mainland until around 4700 years ago. Suggested reasons for its extinction there have included 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...
, or an extremely dry period.
Behaviour and social organisation
The Tasmanian Nativehen's social organisation has been extensively studied. Tasmanian Nativehens live in groups of between two and five, plus the young birds from the previous breeding season, which tend to stay with the group and contribute to the care of the young until they move off to establish their own territories after approximately one year. The sedentary nature of the species means that groups hold sharply defined territories of up to 5 acres (2 ha), and repel transgression into their territory vigorously with calls and displays. Fights can also occur, where birds will jump, peck and kick at each other violently, sometimes drawing blood and pulling feathers.The breeding structure may be monogamous or polygamous, usually polyandrous. Each group contains a single breeding female who will mate with all the males of the group. The unusual social structure based on groups who stay together is not known to occur in many other species; the high ratio of male chicks to female chicks hatched is thought to be a possible explanation for this.
The Tasmanian Nativehen has 14 separate calls, ranging from low grunts to high pitched alarm calls as well as a see-sawing duet performed in unison, rising to a crescendo of harsh screeching notes, It also calls at night.
Although flightless, this bird is capable of running quickly and has been recorded running at speeds up to 48 kilometres per hour (29.8 mph), It uses its wings when running fast to help it to balance.
Breeding
The breeding season begins in the period from July to September, depending upon rainfall and the availability of food. Birds will usually breed once per year, however in good years, with high availability of food, two broods may be produced. The nest is a rough, flattened grass mattress, among taller grasses and is usually built close to water, or on damp ground. With a clutch size of five to eight, the oval eggs measure around 56 by 38 mm (2.2 by 1.5 in) and are a dull yellow or buff to brown with some spotting of reddish brown and lavender. As well as the primary nest, nursery nests are constructed with the purpose of roosting with chicks at night and as hiding places in case of predators. Chicks are covered in a dark brown fluffy down.Diet
The diet of the Tasmanian Nativehen is mostly made up of grass shoots and the leaves of low herbs which it grazes during daylight hours. Birds will also eat insects, seeds and orchard fruit. The species has a reputation among farmers as an agricultural pest. The damage to agriculture was extensively studied in the 1960s by M Ridpath and G Meldrum, who found that although there is some damage to crops, rabbits were responsible for more damage. Many beliefs held by farmers about damage to crops were found to be unlikely, with damage probably caused by other species.The Tasmanian Nativehen is a secondary grazer, meaning that it depends on other species to keep grass swards low and with fresh shoots. Before European settlement in Tasmania, the cleared spaces required for feeding would probably have been provided by Indigenous burning of grasslands to provide feeding grounds for mammals, which would be hunted for food. The expansion of these cleared grassy areas, and the introduction of rabbits, has provided greater food sources and consequently greater numbers of the species within its range.
Conservation status and threats
The Tasmanian Nativehen is currently classified as a species of least concern by the IUCN. Although there is a healthy population size and no significant falls have been measured, there is concern about the recent introduction of the red foxRed Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...
to Tasmania and the possible impact that it will have on this and other species.
As of 15 August 2007, the Tasmanian Nativehen was listed as protected under Tasmanian legislation. Prior to this the Tasmanian Nativehen was one of only four native birds that had no legal protection outside national parks and other reserves in the state of Tasmania—the last of Tasmania's 12 endemic bird species with this dubious status. The three remaining unprotected native species are the Forest Raven
Forest Raven
The Forest Raven is a large species of the crow genus native to south-eastern Australia and Tasmania.-Description:The Forest Raven is 50–52 cm in length with glossy black plumage and a white iris. It has a proportionately larger bill and shorter tail than the other mainland corvid species and...
, the Great Cormorant
Great Cormorant
The Great Cormorant , known as the Great Black Cormorant across the Northern Hemisphere, the Black Cormorant in Australia and the Black Shag further south in New Zealand, is a widespread member of the cormorant family of seabirds...
, and the Little Pied Cormorant
Little Pied Cormorant
The Little Pied Cormorant, Little Shag or Kawaupaka is a common Australasian waterbird, found around the coasts, islands, estuaries, and inland waters of Australia, New Guinea, New Zealand, Malaysia, and Indonesia, and around the islands of the south-western Pacific and the sub-Antarctic...
. All other native Tasmanian birds are listed as protected under the state's Nature Conservation Act 2002.