Australian White Ibis

Taxobox
name = Australian White Ibis
status = LC
status_system = IUCN3.1


regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Ciconiiformes
familia = Threskiornithidae
subfamilia = Threskionithinae
genus = "Threskiornis"
species = "T. molucca"
binomial = "Threskiornis molucca"
binomial_authority = Cuvier, 1829
subdivision_ranks = Subspecies
subdivision =
* "T. m. molucca" (Australasian White Ibis)
* "T. m. pygmaeus" (Solomon Islands White Ibis)

The Australian White Ibis ("Threskiornis molucca") is a wading bird of the ibis family Threskiornithidae, also known as the "Sheep bird". It is widespread across much of Australia. It has a predominantly white plumage with a bare, black head and long downcurved bill and black legs.

Historically rare in urban areas, the Australian White Ibis has immigrated to urban areas of the east coast in increasing numbers since the late 1970s; it is now commonly seen in Wollongong, Sydney, the Gold Coast, Brisbane and Townsville. Debate continues on whether to consider it a pest or vulnerable species. Populations have disappeared from natural breeding areas such as the Macquarie Marshes in northwestern New South Wales. Despite this, the species has been culled in parts of Sydney due to their smell and at times obtrusive nature.

Taxonomy

It was initially described by Georges Cuvier in 1829 as "Ibis molucca". It is considered part of a superspecies complex with the Sacred Ibis ("T. aethiopicus") of Africa, and the Black-headed Ibis ("T. melanocephalus") of Asia. Its status with the complex has vacillated over the years. Many older guidebooks referred to the bird as a species "T. molucca", until a comprehensive review of plumage patterns by Holyoak in 1970. Holyoak noted the three species' similarities and that the Australian taxon resembled "T. aethiopicus" in adult plumage and "T. melanocephalus" in juvenile plumage. He proposed they all be considered part of a single species "T. aethiopicus". This was generally accepted by the scientific community until Lowe and Richards assessment of plumage in 1991. cite journal |author=Lowe KW, Richards GC | year = 1991| title =Morphological Variation in the Sacred Ibis "Threskironis aethiopicus" Superspecies Complex | journal =Emu | volume =91 | issue =1 | pages =41–45 | doi =10.1071/MU9910041 | url =http://www.publish.csiro.au/paper/MU9910041.htm (abstract) | accessdate = 2008-06-14| doi_brokendate =2008-06-28] They again recommended the recognition of "molucca" at species level. This was followed by chromosome study which highlighted each of the three species having a different karyotype. [ cite journal |author=de Boer LE, van Brink JM | year =1982 | title =Cytotaxonomy of the Ciconiiformes (Aves), with karyotypes of eight species new to cytology | journal =Cytogenet Cell Genet. | volume = 34| issue =1-2 | pages =19–34 | pmid =7151490 | url =http://www.ncbi.nlm.nih.gov/pubmed/7151490 (abstract) | accessdate = 2008-06-14] The Australian White Ibis has been considered a full species by most authorities since then.cite book |title=Systematics and Taxonomy of Australian Birds|author=Christidis L, Boles WE |year=2008 |publisher=CSIRO Publishing |location=Canberra |isbn=9780643065116 |pages=p. 113]

Alternate colloquial names include "Tip Turkey", from its habit of rummaging in garbage, and "Sheep-bird".

ubspecies

Two subspecies are recognised:
* "T. m. molucca" of mainland Australia, is the nominate subspecies.
* "T. m. pygmaeus" is a dwarf form found on the Solomon Islands that has been considered a separate species at times.

Description

The Australian White Ibis is around 65-75 cm (25-30 in) long and has a bald black head and neck and a long black downcurved beak, measuring over 16.7 cm (6.6 in) in the male, and under in the female. There is some sexual dimorphism in size, as the slightly heavier male weighs 1.7-2.5 kg (3.7-5.5 lb) compared to the 1.4-1.9 kg (3.1-4.2 lb) female.cite web |url=http://www.environment.nsw.gov.au/resources/nature/wildAboutIbis.pdf |title=Wild about ibis: living with urban wildlife |accessdate=2008-06-15 |author=Legoe C, Ross G "(eds.)" |date=April 2007 |work=Department of Environment and Climate Change, New South Wales - website |publisher=Department of Environment and Climate Change NSW] The body plumage is white with some black feathers near the tail, although may become brown-stained. The upper tail becomes yellow when breeding. The legs and feet are dark and red skin is visible on the underside of the wing. Immature birds have shorter bills.cite book | author = Simpson K, Day N, Trusler P | title = Field Guide to the Birds of Australia | publisher = Viking O'Neil | date = 1993 | location = Ringwood, Victoria | pages = p. 54 | isbn = 0-670-90478-3] The head and neck are feathered in juveniles.

The call is a long croak.

The Australian White Ibis reaches sexual maturity in 3 years, and can reach 28 years of age.

Distribution and habitat

The Australian White Ibis is widespread in eastern, northern and south western Australia. It occurs in marshy wetlands, often near open grasslands and has become common in Australian east coast city parks and rubbish dumps, in the urban areas of Wollongong, Sydney, the Gold Coast, Brisbane and Townsville. Historically a rare bird in urban areas, the first influx was noted after drought conditions drove birds eastwards in the late 1970s. The urban population further increased after a further period of drought in 1998.cite web
publisher = Australian Broadcasting Corporation
url = http://www.abc.net.au/science/scribblygum/november2007/
title = Ibis invasion
accessmonthday = November 22
accessyear = 2007 ]

There has been debate in recent years over whether to consider them a pest or a possibly endangered species. Birds in tourist areas of Sydney such as Darling Harbour, the Royal Botanic Gardens, or Centennial Park have been a problem due to their strong smell. Populations in the latter two areas have been culled.cite web
publisher = The Sydney Morning Herald
url = http://blogs.smh.com.au/science/archives/2006/10/_they_seem_to_b.html
title = Ibises–cull them or cuddle them?
accessmonthday = November 5
accessyear = 2006 ] .The birds have also come to be regarded as a problem species in Victoria as a result of their scavenging activities, scattering rubbish from tips and bins in the process. They are even known to snatch sandwiches from picknickers. Such behaviour, together with their propensity to build nests in "inappropriate" places, and competition with captive animals led to surplus birds being relocated from Healesville Sanctuary to Sale. However, the birds returned in a few days.cite web|author=Temby, I
publisher = Department of Primary Industries (Victoria)
url = http://www.dpi.vic.gov.au/DPI/nreninf.nsf/childdocs/-C3270146B772814F4A2568B30006FFEE-7A5820241AEA1564CA256BC800078098-7B785784C934E20E4A256DEA00292002-5C86567E14FCF0C6CA256BDE0028961F?open
title = Problems caused by the Australian White Ibis
accessmonthday = June 29
accessyear = 2008]

The Macquarie Marshes in northwestern New South Wales was one of the main areas for breeding, however none have been reported breeding there since 2000, from 11000 pairs in 1998.

Behaviour

Feeding

This ibis feeds on various fish, frogs and other water creatures, and also insects and garbage.

Breeding

Breeding season varies with the location within Australia, generally August to November in the south, and February to May, after the Wet Season, in the north. The nest is a shallow dish-shaped platform of sticks, grasses or reeds, located in trees and generally near a body of water such as river, swamp or lake. Ibis commonly nest near other waterbirds such as egrets, herons, spoonbills or cormorants. Two to three dull white eggs are laid measuring 65 mm x 44 mm. [cite book | last = Beruldsen | first = G | title = Australian Birds: Their Nests and Eggs | publisher = self | date = 2003 | location = Kenmore Hills, Qld | pages = p. 177 | isbn = 0-646-42798-9] The clutch is then incubated for 21-23 days. Hatchlings are altricial, that is they are naked and helpless at birth, and take 48 days to fledge.

References

* Database entry includes justification for why this species is of least concern