Feature Article - The Endemic birds of Tasmania
Feature article published in the Tasmanian Year Book, 1972 (cat. no. 1301.6)
The following article was contributed by Mr D. G. Thomas, President, Bird Observers’ Association of Tasmania.
INTRODUCTION
In common with most islands Tasmania has an impoverished birdlife (avifauna) with only fifteen species of birds being endemic i.e. exclusively breeding in Tasmania, and a further twenty-six subspecies recognised as island races of continental species. Of 176 land and fresh-water birds breeding in Victoria in habitats similar to those found in Tasmania, only 104, or 59 per cent, also breed in this State. The reasons for this are not fully understood, but are more likely to be associated with ecological factors within Tasmania than with any inability to cross Bass Strait.
Birds which have differentiated sufficiently to be regarded as species different from their closest relatives are usually thought to have been the earliest colonists. Those species in which island populations cannot be distinguished from mainland birds are usually considered to be the most recent arrivals. A subspecies is intermediate between the two but recent evidence has shown that an isolated population may develop into a new subspecies within a few generations. In view of this, the accepted theory may have to be reconsidered but when discussing the endemic birds of Tasmania, the chronological concept is still a useful working hypothesis.
It should be pointed out that opinions differ as to the dividing line between species and subspecies. Some Tasmanian birds which were once regarded as being endemic are now thought to be subspecies of more widely distributed species. For example, the Tasmanian Masked Owl is now regarded as being a subspecies of the mainland Masked Owls.
Throughout this article both the English and Latin names are those used in the Official Checklist of the Birds of Australia published in 1926 by the Royal Australasian Ornithologists Union. The vernacular names used in various parts of the State may differ from 'official' usage. In the interests of clarity, 'official' names have been retained and it is hoped that they will become more generally used.
CLIMATE AND HABITAT
Introduction
The distribution of birds is determined by their habitat and food preferences. Tasmanian habitats can be divided roughly into two categories, depending on the tolerance of the vegetation to temperature and rainfall.
Cold-wet adapted habitats occur over much of the western half of the State, with isolated pockets at Ben Lomond, Mount Elephant, eastern Tasman Peninsula and South Bruny Island. Warm-dry adapted habitats occupy the rest of the State and Flinders, King and Maria Islands.
The distribution of vegetation was very different at the height of the last glaciation during the Pleistocene epoch which occurred about 18,000 years ago. During this period Tasmania was part of the Australian continent. With the enormous amount of water locked-up in the icecaps, the sea-level fell to such an extent that Tasmania was connected to Victoria by a land-bridge through the Furneaux group of islands; King and Maria Islands were also connected to Tasmania. Elsewhere, the steeply sloping continental shelf would have resulted in a seaward extension of the land surface of up to 15 miles. Only small amounts of the present warm-dry habitats would probably have existed.
From 18,000 years ago the climate warmed-up and the sea-level rose, progressively separating Flinders Island from Victoria, King and Maria Islands from Tasmania and finally severing the Tasmania-Flinders Island link.
During the last 6,000 or so years in which the Victoria-Flinders Island land-bridge existed, the extent of warm-dry habitats would have increased, the species spreading south as the temperature rose.
Cold-Wet Habitats
The present-day cold-wet adapted habitats comprise:
Temperate Rain Forest: Dominated by the Antarctic Beech, Nothofagus cunninghami, which occurs from sea-level to 3,000 feet where annual rainfall exceeds 45 inches. Within this area occur wet gullies where the dominant vegetation is tree ferns and mosses.
Sub-Alpine Forest: Occurs from 3,000 feet to the tree-line. The dominant tree is the Snow Gum, Eucalyptus coccifera, and there is a rich shrub-layer which includes the deciduous Beech, Nothofagus gunnii.
High Moors: Occurring from 3,000 feet upwards, the dominant species are Snow Grass, Poa Coespitosa, on the better drained soils and Pineapple Grass, Astelia alpina, in less well-drained sites.
Wet Sedgelands: Better known as 'Button Grass Plains'; occurring from sea-level to 3,000 feet. Button Grass, Mesomelaena sphaerocephala, is the dominant plant, often forming almost pure stands.
Warm-Dry Habitats
The warm-dry habitats consist of:
Low-Altitude Heath: Occurs on deep sandy soils, mainly in coastal areas.
Savannah Woodland: Occurs mainly in the Midlands where the rainfall is less than 22 inches and consisted originally of native grasses and scattered eucalypts. Large areas of native grasses have been replaced by improved pasture.
Dry Sclerophyll Forest: The dominant formation over much of eastern Tasmania, where the yearly rainfall is 22-30 inches. It is made up mainly of eucalypts, the species depending on rainfall, drainage, soil, altitude and aspect.
Wet Sclerophyll Forest: Occurs in areas with a rainfall of 30-50 inches. It consists of tall eucalypts with a tree under-storey or well-developed shrub layer.
The above reconstruction of the history of the vegetation and habitat classification is after Ridpath and Moreau (1966). It is of interest because it might be expected that the endemic birds would be associated with the cold-wet habitats which are thought to have been in existence for at least 18,000 years.
ENDEMIC SPECIES
Tribonyx mortierii (Native Hen)
This large flightless bird is generally greenish-brown in colour with a conspicuous white mark on its flanks. It is common near water throughout eastern Tasmania and is regarded officially as a ‘pest species’ because of the damage it is supposed to do to crops. This aspect has been studied by Ridpath and Meldrum (1967 a, b) who concluded that wide-spread control campaigns are neither necessary nor desirable. Flightless species such as T. mortierii and other species confined to islands are particularly vulnerable and many have become extinct.
Platycercus caledonicus (Green Rosella)
This bird varies a great deal in the brilliance of its plumage which is dark green with yellow breast and red forehead. It is a very widespread species appearing in most forested areas and is by no means restricted to cold-wet habitats.
Lathamus discolor (Swift Parrot)
Mainly green in colour with red forehead, shoulders, throat and tail, the Swift Parrot is confined to the warm-dry habitats. It is migratory, spending the winter as far north as Queensland, an unusual habit for an island endemic. However, the Swift Parrot is not known to breed on the mainland.
Petroica vittata (Dusky Robin)
The sexes are indistinguishable in the field, both males and females retaining dull brown immature plumage. In other Tasmanian robins the male has black or slate upperparts and is red or pink on the underparts.
It typically occurs on the edges of forest or light scrub, with the greatest numbers appearing in the eastern parts of the State, and only sparingly in the cold-wet habitats, e.g. Lake Pedder.
Acanthiza ewingii (Tasmanian Thornbill)
A small bird, light brown with white flanks and under-tail. The Tasmanian Thornbill occurs in cold-wet habitats. With the Brown Thornbill, A. pusilla, it represents a double invasion of Tasmania by birds derived from a common stock. Although the two are similar in appearance, the Tasmanian Thornbill has differentiated more from mainland forms and is regarded as a full species. The Brown Thornbill has differentiated only at a subspecies level which suggests it was later reaching Tasmania. This is substantiated by distinct habitat variations.
Acanthornis magnus (Scrub Tit)
Generally olive-brown with a white throat. The Scrub Tit forms a monotypic genus. It is restricted to habitats with a distinctive endemic vegetation (wet fern gullies) belonging to the cold-wet formations, suggesting that it has been in Tasmania for a very long time. This restriction to a particular habitat also suggests that it is a relict species that once had more widespread distribution. According to Ridpath and Moreau it is the only species that can be considered with any certainty to have been present in Tasmania during the last glaciation.
Sericornis humilis (Brown Scrub-Wren)
The Brown Scrub-Wren is deep brown in colour with a white spot on the edge of the wing. It occurs in thick cover close to the ground and is most numerous in the cold-wet habitats. Commonly found in wet sclerophyll forest, it occurs sparingly in dry sclerophyll forest.
Further research will probably show that the Brown Scrub-Wren is in fact not a distinct species but a large subspecies of the mainland Whitebrowed Scrub-Wren, S. frontalis.
Pardalotus striatus (Yellow-tipped Pardalote)
P. striatus, also known as the Striated Pardalote, is grey with a white streaked black head and an orange-yellow bright spot on the wing. It is restricted to warm-dry habitats. Like the Swift Parrot, the Yellow-tipped Pardalote migrates to the mainland, although a few birds may winter in Tasmania.
P. quadragintus (Forty-spotted Pardalote)
Slightly larger than the Yellow-tipped Pardalote, the Forty-spotted Pardalote retains the juvenile plumage, being grey and olive-green with a yellow face. Known only to exist in warm-dry habitats at five localities - Flinders Island, Maria Island, Saltwater River, Tinderbox and North Bruny Island - the Forty-spotted Pardalote is the least numerous of the Tasmanian endemics. It is believed the total population does not exceed 1,000 individuals and that the species is close to extinction.
Melithreptus validirostris (Strong-billed Honeyeater)
Brownish-olive with a white crescent on a black neck, this honeyeater occurs in both dry and wet sclerophyll forests, particularly in the latter, where ever there are tall rough-barked trees. It obtains much insect food from the tree bark, a habit reminiscent of mainland tree-creeping birds which do not occur in Tasmania. In winter it forms noisy nomadic flocks.
M. affinis (Black-headed Honeyeater)
This bird is similar in appearance to the Strong-billed Honeyeater from which it can be distinguished by the absence of white on the back of the neck. Mainly a bird of the warm-dry habitats it forages among the foliage. Like the Strong-hilled Honeyeater it forms nomadic winter flocks, at times entering suburban areas.
Meliphaga flavicollis (Yellow-throated Honeyeater)
The Yellow-throated Honeyeater is green with a yellow throat. It is very common in all forested areas and is another species that has adopted the bark-feeding habit to some extent. Pairs tend to remain in the same area throughout the year although a few birds, probably young birds, spend the winter in suburban areas.
Authochaera paradoxa (Yellow Wattlebird)
The largest of all Australian honeyeaters, the Yellow Wattlebird is yellowish-brown with yellow wattles (comb). It breeds in dry and wet sclerophyll forests. Outside the breeding season it is nomadic following the blossoming of the various eucalypts and also coming into suburban gardens; large numbers congregate in east coast orchards. The Yellow Wattlebird is a succulent game bird and in most years there is an open season lasting a few days.
Strepera fulginosa (Black Currawong)
Also known as the Black Jay, this bird is black with white tips and edges to its wings. It predominantly occurs in cold-wet formations and only sparingly throughout the dry sclerophyll forests of the Eastern Tiers. The Black Currawong can become remarkably tame, a characteristic often noted by visitors to Mount Field National Park or Waldheim.
S. arguta (Clinking Currawong)
A uniform dark grey in colour with white-edged and tipped tail. The Clinking Currawong (Black Magpie) is restricted to the warm-dry habitats of the eastern part of the State, being particularly plentiful in the low-altitude heaths of the north-east.
ENDEMIC SUBSPECIES
Dromaius novaehollandiae (Emu)
Reputed to be common in early settlement days, this flightless bird is now extinct. It must have arrived in Tasmania before the land bridge disappeared.
Synoicus australis (Brown Quail)
The Brown Quail has brown plumage with darker spots. A game bird, it is restricted to warm-dry habitats, low-altitude heath, savannah woodland and dry sclerophyll forest.
Rallus pectoralis (Lewin Water Rail)
Dark brown with black and white streaks. Rails and crakes are a difficult study in the field, being rarely seen denizens of reed-beds and marshes. As a result, the distribution of the Water Rail in Tasmania has not yet been established.
Aquila audax (Wedge-tailed Eagle)
Blackish-brown in colour, the Wedge-tailed Eagle is common in suitable localities although Sharland (1958) estimated that there were probably only 100 birds in Tasmania. As each pair has a home range of many square miles these magnificent birds can often be seen soaring and gliding in places as far apart as Cape Portland, the Hazards, Mount Olympus and even Knocklofty (a foothill of Mount Wellington). The Wedge-tailed Eagle is fully protected in Tasmania despite claims that it often kills lambs. It is by no means certain that the eagle kills healthy lambs although it will take weak, dying and dead animals. This is being investigated by the C.S.I.R.O. in Western Australia.
Ninox novaeseelandiae (Spotted Owl)
Sometimes called the Boobook or Morepork Owl, the Spotted Owl is dark brown with white spots. As with other owls it is rarely seen in daylight when it hides in hollow trees or thick scrub in the dry sclerophyll forest or around homesteads and towns where it also occurs. At night its call, ‘morepork’, is a familiar sound of the bush.
Tyto novaehollandiae (Masked Owl)
Easily distinguished by its buff or chestnut coloured facial disk (white in mainland birds), the Masked Owl has a blackish-brown body spotted with white. It normally occurs in dry sclerophyll forest although it has been recorded in wet sclerophyll forest.
Platycercus eximius (Eastern Rosella)
Strikingly coloured with red, blue and green plumage, the Eastern Rosella has a very restricted distribution. Common only in savannah woodland, orchards and cultivated pastures it is confined to the eastern parts of the State and unknown in cold habitats. Elsewhere it has been replaced by the endemic Green Rosella to which it is closely related and with which it has been known to interbreed.
Pezoporus wallicus (Ground Parrot)
Bright green in colour with yellow spots. The Ground Parrot is found in the south-west where it inhabits the Button Grass Plains and coastal heath. Elsewhere it should be looked for in coastal heath although it is less common there than it once was because frequent burning of the heath has given rise to vegetation too sparse for its requirements. Tasmania is the stronghold of this rarely seen bird, the presence of which is best detected at dusk and dawn when, for a few minutes, it calls. The call is a plaintive low whistle of several distinct notes of ascending scale.
Podargus strigoides (Tawny Frogmouth)
During the day the Tawny Frogmouth remains motionless on its perch being very hard to detect with its camouflaging plumage of dappled brown and grey. Confined to the warmer habitats, it is common in the more open dry sclerophyll forests. It is insectivorous, hunting at dusk and during the night.
Aegotheles cristata (Owlet-Nightjar)
Blackish-grey in colour, the Owlet-Nightjar like the Tawny Frogmouth, is a nocturnal insect hunter. Its distribution is also similar. Although common it is less well-known, hiding in hollow trees during the day.
Rhipidura fuliginosa (Grey Fantail)
Grey and black with white outer tail feathers this well-known bird, also called the ‘Cranky Fan’, is widely distributed in a variety of habitats. It is a partial migrant to the mainland, with some birds remaining in Tasmania throughout winter when they become nomadic.
Pachycephala pectoralis (Golden Whistler)
The Golden Whistler has black and white plumage, the male having a yellow breast. In Tasmania it is common in both dry and wet scleroplyll forests but in many parts of south-eastern Australia it is found in the wetter habitats.
Colluricincla harmonica (Grey Shrike-Thrush)
Grey in colour as the name indicates, the Shrike-Thrush is a very well-known bird occurring in a wide range of habitats. In this State it searches the bark and branches of trees for insects, a habit it has not developed on the mainland.
Coracina novaehollandiae (Black-faced Cuckoo-Shrike)
This bird has smoke-grey plumage with a black face and throat. It is most common in dry sclerophyll forest. Few birds winter in Tasmania, the majority migrating to the mainland.
Cinclosoma punctatum (Spotted Quail-Thrush)
Mainly brown and grey with a long white-tipped tail. The Spotted Quail-Thrush occurs in the warmer habitats and is perhaps the only bird in Tasmania that is restricted to dry sclerophyll forest.
Epthianura albifrons (White-fronted Chat)
This quite common bird, with black and white plumage, appears to fill the ‘wagtail’ niche in Tasmania. It is common on river-flats and marshes but also occurs in poor, dry grassland provided some cover is available. Apparently the Chat has increased in numbers since 1880. The nature of its movements is not known but it does appear to move about to some extent.
Acanthiza pusilla (Brown Thornbill)
The Brown Thornbill is brown in colour with a black streaked breast. It is restricted to the warm-dry habitats. A. pusilla has differentiated only subspecifically from the mainland forms; however, with A. ewingii (Tasmanian Thornbill) it represents a double invasion of Tasmania by birds of the same stock. The Tasmanian Thornbill has differentiated sufficiently to be regarded as a separate species.
Megalurus gramineus (Little Grassbird)
The Little Grassbird, with its body a streaked brown colour, is camouflaged perfectly for its reed-bed habitat. It is uncommon mainly because of the lack of suitable habitat.
Stipiturus malachurus (Southern Emu Wren)
The Southern Emu Wren has brown plumage, the male also having a blue throat. Its habitat is patches of scrub surrounded by Button Grass although it does occur in reed beds. The Emu Wren is one of the few endemic subspecies that is restricted to the western part of the State.
Zosterops Iateralis (Grey-breasted Silver Eye)
Green with a white-ringed eye, this bird breeds in many habitats, most commonly in low-altitude heath and wet sclerophyll forest. Outside the breeding season many birds migrate to the mainland while others form flocks which remain in Tasmania, moving wherever food is available.
Gliciphila melanops (Tawny-crowned Honeyeater)
The Tawny-crowned honeyeater is a dull grey-brown with a light crown. It is restricted to coastal heath.
Acanthorhynchus tenuirostris (Eastern Spinebill)
Mainly reddish-brown in colour, the Eastern Spinebill is a common breeding species in low-altitude heath. It is one of the few Tasmanian honeyeaters that relies heavily on nectar and has a long, curved thin bill particularly well suited to extracting nectar from tubular flowers. In winter it is nomadic, being common in dry sclerophyll forest, feeding on the heath Epacris impressa.
Myzantha melanocephala (Noisy Miner)
With a grey plumage and black crown the Noisy Miner is common in savannah woodland, orchards and cultivated pastures. The bird has a similar distribution to that of the Eastern Rosella occurring in colonies consisting of a breeding male and female with several non-breeding helpers which assist in feeding the young.
Corvus tasmanicus (Raven)
A large all-black bird often called a crow, the Raven occurs in a wide range of habitats in Tasmania. The Australian corvids classification has been revised recently and the only one that occurs in this State is the Forest Raven. Apparently one race occurs in Tasmania, the Otway Ranges and Wilsons Promontory and a second race in the New England tablelands, so perhaps the Tasmanian bird should no longer be considered an endemic subspecies. Its distribution is interesting, suggesting it is a relict species that was once more widespread.
Cracticus torquatus (Grey Butcherbird)
Generally black with grey upperparts, it is restricted to dry sclerophyll forests and habitats associated with man. A meat eater, the Grey Butcherbird will sometimes destroy small caged birds and will also catch Sparrows, Goldfinches and similar birds.
Gymnorhina hypoleuca (White-backed Magpie)
The White-backed Magpie is easily recognised with its strongly contrasting black and white plumage. It is a common bird that sometimes lives in large groups which have a single breeding pair and has a distribution similar to that of the Eastern Rosella and Noisy Miner. As the Tasmanian birds are so much smaller than those found on the mainland, some researchers regard the Magpie as distinct at the specific level. Once more widespread, it currently appears to be extending its range.
SUMMARY
Of the fifteen endemic species only two (Tasmanian Thornbill and Scrub-Tit) occur exclusively in the cold-wet formations although two others, Brown Scrub-Wren and Black Currawong, are most numerous in these habitats. As far as the endemic subspecies are concerned only the Southern Emu Wren is restricted to these ‘older’ formations, although the Wedge-tailed Eagle and Ground Parrot are common.
Undoubtedly dry sclerophyll forests have the greatest number of common breeding species.
Because a greater proportion of endemic species than subspecies is found in the cold-wet formations, support is lent to the idea that these were the first to reach Tasmania. Ridpath and Moreau (1966) concluded that only one species, the Scrub-Tit, could with certainty have been present 18,000 years ago when the last glaciation was at its height. However, the evidence was inconclusive for the Tasmanian Thornbill and the Forty-spotted Pardalote.
The remaining species entered Tasmania some time after the height of the glaciation, many probably arriving across the land-bridge i.e. over 12,000 years ago.
REFERENCES
Ridpath, M. G. and Meldrum, G. K. - 1967a Damage to pastures by the Tasmanian Native Hen, Tribonyx mortierii, C.S.I.R.O. Wildl. Res. 13: 11-24.
Ridpath, M. G. and Meldrum, G. K. - 1967b Damage to oat crops by the Tasmanian Native Hen, Tribonyx mortierii, C.S.I.R.O. Wildl. Res. 13: 25-43.
Ridpath, M. G. and Moreau, R. E. - 1966 The Birds of Tasmania: Ecology and Evolution Ibis 108: 348-393.
Sharland, M. S. R. - 1958 The Birds of Tasmania. Third edition. Sydney: Angus and Robertson.
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