Brolga
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| Brolga Conservation status: Secure | ||||||||||||||
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| Grus rubicunda (Perry, 1810) |
The Brolga (Grus rubicunda) is a bird in the crane family. When first described 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 bird was later given the name "Australian Crane" in 1865 by well-known ornithological artist John Gould.
In 1926 the Royal Australasian Ornithologists Union made "Brolga", a popular name derived from an Australian Aboriginal native language, the official name of the bird. It is sometimes referred to as the "Native Companion". The Brolga is a common wetland congregating bird species in tropical and eastern Australia, well known for its intricate mating dance.
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Appearance
The full-grown Brolga is a tall, mid-grey to silver-grey crane, 0.7 to 1.3 m high, with a wingspan of 1.7 to 2.4 m, 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 weigh a little under 7 kg, females a little under 6 kg.
Diet
Brolga are omnivorous and eat a variety of wetland plants, insects, invertebrates, and small vertebrates such as frogs. They also eat wetland and upland plants, grains, mollusks, and crustaceans. Northern Austalian 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.
Distribution
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 and is not considered to be threatened. The International Crane Foundation began a captive breeding population with three pairs of wild Brolga which were captured in 1972. Brolga are non-migratory but do move in response to seasonal rains.
Related species
The Brolga is closely related to other cranes like the Sarus Crane of Australia and Southeast Asia, with which it can easily be confused. However the Sarus' 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. The bird is also related to the Old World Common Crane, and, more distantly, to the Blue Crane of South Africa.
Social groups
There are many Brolgas on the endless Australian plains today. 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.
Mating and breeding
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.
In the breeding season, which is largely determined by rainfall rather than the time of year, 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.
A pair of spotted or blotched white eggs are most common, but sometimes the clutch is one or three, 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.
Australian Aboriginal mythology
In the Aboriginal dreamtime, Brolga was a young woman of extraordinary beauty, and a wonderful dancer. She learned the old dances—parading like an emu and whirling like the wind—and invented new ones to tell the stories of the spirits and the animals. People of far-away tribes came just to see her dancing, and the more she danced the more famous she became. Sometimes the old people would worry that, because she was so pretty and so famous, she might grow vain; but she never did. She remained the same happy, modest Brolga she had always been.
One day, Brolga went alone out onto the plain to dance, just for the joy of it, when an evil spirit spied her. The evil spirit felt he must possess her. He came in the form of a willywilly and spun her away. Her people became worried and searched for her, but the wind had blown away her footprints. They searched for many days before they found the willywilly on a distant plain, and Brolga there beside him. They all ran to rescue her, waving their spears and boomerangs, but the evil spirit spun the whirlwind faster and faster. If he could not have Brolga, he said, no-one would have her. He swirled around her and just as the tribe came close, she vanished into the sky.
Soon after all these events, a bird appeared, one that they had never seen before; a beautiful tall, grey bird. Slowly, it stretched its wings and began to dance, making long hopping steps and floating on the air with the same grace and poetry of motion that Brolga had been famous for. Soon the people realised that Brolga had escaped from the evil spirit and been turned into a bird so that she could fly back to Earth and dance for them again.
References
- MacDonald JD (1987) The Illustrated Dictionary of Australian Birds by Common Name, Reed, p40, ISBN 0-7301-0184-3
- Slater P, Slater P and Slater R (1995) The Slater Field Guide to Australian Birds, Landowne Publishing Pty Ltd, Sydney, NSW, Australia, p50, ISBN 0-947116-99-0
External links
- Unique Australian Animals (http://australian-animals.net/brolga.htm)– Brolga "reddish crane"
- All Info About Myths (http://myths.allinfoabout.com/feature79.html)– a copy of the Brolga's Dreamtime myth
- International Crane Foundation's Brolga page (http://www.savingcranes.org/species/brolga.cfm)fr:Grue brolga