Brolga Crane
Brolga Crane
The Brolga (Grus rubicunda), formerly known as the "Native
Companion", is a bird in the crane family. The bird has also been given the name
"Australian Crane", a term coined in 1865 by well-known ornithological artist
John Gould in his Birds of Australia.
The Brolga is a common gregarious wetland bird species in tropical and eastern
Australia, well known for its intricate mating dance. It is the official bird
emblem of the state of Queensland.
When first described by the
naturalist George Perry in 1810, the Brolga was misclassified as Ardea, the
genus that includes the herons and egrets. It is in fact a member of the
Gruiformes—the order that includes the crakes, rails, and cranes, and a member
of the genus Grus. The Royal Australasian Ornithologists Union made Brolga, a
popular name derived from Gamilaraay burralga, the official name of the bird in
1926.
The Brolga, Sarus Crane (Grus antigone), and White-naped Crane (G. vipio) were
seen as forming a natural group on the basis of similarities in calls in 1976.
This was further confirmed by molecular studies of DNA. It is unclear which two
of the three species are most closely related.
The full-grown Brolga is a tall, mid-grey to silver-grey crane, 0.7–1.3 m
(3.3–4.3 ft) high, with a wingspan of 1.7–2.4 m (5.6–7.9 ft), and a broad red
band extending from the straight, bone-coloured bill around the back of the
head. Juveniles lack the red band. Adult males average at a little under 7 kg
(15 lb), females a little under 6 kg (13 lb). The weight can range from 3.7 to
8.7 kg (8.1-19.2 lb).
The Brolga can easily be confused with the Sarus Crane, however the latter's red
head colouring extends partly down the neck while the Brolga's is confined to
the head. Additionally, in Australia the range of the Sarus is limited to a few
scattered localities in northern Australia, compared to the more widespread
distribution of the Brolga.
Brolgas are widespread and often abundant in north and north-east Australia,
especially north-east Queensland, and are common as far south as Victoria. They
are also found in southern New Guinea and as rare vagrants in New Zealand and
the northern part of Western Australia. The population is estimated at between
20,000 and 100,000. The International Crane Foundation began a captive breeding
population with three pairs of wild Brolga that were captured in 1972. Brolga
are non-migratory but do move in response to seasonal rains.
Brolga are not listed as threatened on the Australian Environment Protection and
Biodiversity Conservation Act 1999. However, their conservation status varies
from state to state within Australia. For example:
* The Brolga is listed as threatened on the Victorian Flora and Fauna Guarantee
Act (1988). Under this Act, an Action Statement for the recovery and future
management of this species has been prepared.
* On the 2007 advisory list of threatened vertebrate fauna in Victoria, the
Brolga is listed as vulnerable.
Brolgas are gregarious creatures; the basic social unit is a pair or small
family group of about 3 or 4 birds, usually parents together with juvenile
offspring, though some such groups are nonfamilial. In the non-breeding season,
they gather into large flocks, which appear to be many self-contained individual
groups rather than a single social unit. Within the flock, families tend to
remain separate and to coordinate their activities with one another rather than
with the flock as a whole.
Brolga are omnivorous and eat a variety of wetland plants, insects,
invertebrates, and amphibians. They also eat wetland and upland plants, seeds,
mollusks, and crustaceans. Northern Australian populations of Brolga are fond of
the tubers of the bulkuru sedge which they dig holes to extract but this is not
available south of Brisbane.
Brolgas are well known for their intricate mating dances. The dance begins with
a bird picking up some grass and tossing it into the air, catching it in its
bill, then progresses to jumping a metre into the air with outstretched wings,
then stretching, bowing, walking, calling, and bobbing its head. Sometimes just
one Brolga dances for its mate; often they dance in pairs; and sometimes a whole
group of about a dozen dance together, lining up roughly opposite each other
before starting.
The brolga breeds throughout its range in Australia and New Guinea. The time of
breeding is largely determined by rainfall rather than the time of year; thus
the season is February to May after the rainy season in the monsoonal areas, and
September to December in southern Australia. The flocks split up and pairs
establish nesting territories in wetlands. In good habitat, nests can be quite
close together, and are often found in the same area as those of the closely
related but slightly larger Sarus Crane. The nest is a raised mound, built by
both sexes, of sticks, uprooted grass, and other plant material sited on a small
island, standing in shallow water, or occasionally floating. If no grasses are
available, mud or roots unearthed from marsh beds are employed. Sometimes they
make barely any nest at all, take over a disused swan nest, or simply lay on
bare ground.
There is one brood produced a year, with clutch size usually two; the dull white
eggs measure 95 x 61 mm and are sparsely spotted or blotched with reddish brown.
The markings are denser at the larger end of the egg. Occasionally one or three
are laid about two days apart. Both birds incubate and guard the young. Hatching
is not synchronised, and takes about 30 days. The chicks hatch covered in grey
down and weighing about 100 g. They can leave the nest within a day or two, have
body feathers within 4 or 5 weeks, and are fully feathered after three months,
and able to fly about two weeks after that. When threatened, chicks hide and
stay quiet while the parents perform a broken-wing display. The parents continue
to guard the young for up to 11 months, or almost two years if they do not
re-nest.
Text from Wikipedia
