Tasmanian Emu
Encyclopedia
The Tasmanian Emu is an extinct subspecies
of the Emu
. It was found on Tasmania
where it had become isolated during the Late Pleistocene
. As opposed to the other insular emu taxa, the King Island
and the Kangaroo Island Emu
, the population on Tasmania was sizable, meaning that there were no marked effects of small population size
as in the other two isolates. Thus, the Tasmanian Emu had not progressed to the point where it could be considered a distinct species
, and even its status as a distinct subspecies is not universally accepted as it agreed with the mainland birds in measurements and the external characters used to distinguish it - a whitish instead of black foreneck and throat and an unfeathered neck - apparently are also present, albeit rare, in some mainland birds. There are suggestions the bird was slightly smaller than the modern Emu, but in conflict, other evidence (including descriptions of Pleistocene remains) indicates that both are similar in size. Today, it is apparently only known from subfossil
bones, the skins which once existed having been lost.
. In addition, the practice of setting fire to grassland and shrubland to aid in claiming land for agriculture deprived the birds of habitat. It is known that in 1838, 2 skin specimens were received by the British Museum
. The subspecies became extinct around 1850, but this date is not very precise: Mainland birds were introduced after diemenensis disappearance (and possibly even when the last birds of the Tasmanian subspecies were still around, hybridizing them out of existence), but the history of emu introductions on Tasmania is not sufficiently documented to allow a more precise dating of the disappearance of diemenensis. Whether a sight record in 1865 and captive specimens that died in 1873 were of this subspecies is not known with certainty. The specimens on the British Museum belonged to a collection which was suffering from bad preparation and/or storage in 1906 already, and they could not be located in 1959. A supposed third specimen in Frankfurt
is erroneously attributed to this subspecies (Steinbacher, 1959).
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Emu
Emu
The Emu Dromaius novaehollandiae) is the largest bird native to Australia and the only extant member of the genus Dromaius. It is the second-largest extant bird in the world by height, after its ratite relative, the ostrich. There are three subspecies of Emus in Australia...
. It was found on 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...
where it had become isolated during the Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...
. As opposed to the other insular emu taxa, the King Island
King Island Emu
The King Island Emu or Black Emu is an extinct sub-species of emu which occurred on King Island between mainland Australia and Tasmania. It is known from 19th century descriptions of live birds, as well as subfossil bones and one museum specimen...
and the Kangaroo Island Emu
Kangaroo Island Emu
Kangaroo Island Emu or Dwarf Emu is an extinct member of the bird family Casuariidae. It was restricted to Kangaroo Island, South Australia, which was known as Ile Decrés by the members of the Baudin expedition. It differed from the mainland Emu mainly in its smaller size...
, the population on Tasmania was sizable, meaning that there were no marked effects of small population size
Small population size
Small populations behave differently from larger populations. They often result in population bottlenecks, which have harmful consequences for the survival of that population.-Demographic effects:...
as in the other two isolates. Thus, the Tasmanian Emu had not progressed to the point where it could be considered a distinct 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...
, and even its status as a distinct subspecies is not universally accepted as it agreed with the mainland birds in measurements and the external characters used to distinguish it - a whitish instead of black foreneck and throat and an unfeathered neck - apparently are also present, albeit rare, in some mainland birds. There are suggestions the bird was slightly smaller than the modern Emu, but in conflict, other evidence (including descriptions of Pleistocene remains) indicates that both are similar in size. Today, it is apparently only known from 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....
bones, the skins which once existed having been lost.
Extinction
The Tasmanian emu was, as the mainland birds, hunted as a pestPest (animal)
A pest is an animal which is detrimental to humans or human concerns. It is a loosely defined term, often overlapping with the related terms vermin, weeds, parasites and pathogens...
. In addition, the practice of setting fire to grassland and shrubland to aid in claiming land for agriculture deprived the birds of habitat. It is known that in 1838, 2 skin specimens were received by the British Museum
British Museum
The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...
. The subspecies became extinct around 1850, but this date is not very precise: Mainland birds were introduced after diemenensis disappearance (and possibly even when the last birds of the Tasmanian subspecies were still around, hybridizing them out of existence), but the history of emu introductions on Tasmania is not sufficiently documented to allow a more precise dating of the disappearance of diemenensis. Whether a sight record in 1865 and captive specimens that died in 1873 were of this subspecies is not known with certainty. The specimens on the British Museum belonged to a collection which was suffering from bad preparation and/or storage in 1906 already, and they could not be located in 1959. A supposed third specimen in Frankfurt
Frankfurt
Frankfurt am Main , commonly known simply as Frankfurt, is the largest city in the German state of Hesse and the fifth-largest city in Germany, with a 2010 population of 688,249. The urban area had an estimated population of 2,300,000 in 2010...
is erroneously attributed to this subspecies (Steinbacher, 1959).