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Despite its (unearned) reputation for lack of intelligence, the Galah is probably the most successful member of the cockatoo family in terms of both distribution and abundance. It has increased its range in historic times and now occurs over almost all of the continent.
Originally the Galah was a bird of open woodland, mallee and all but the most arid deserts in the interior of Australia. It generally avoided coastal areas and was not found in the tall forests of the eastern ranges or in the more humid areas of the south-west. Although early records suggest that some natural movements have always occurred between Tasmania and the mainland, it is only within the past century that it has become a common breeding resident in the island State. Over the same period, it has moved into the Eastern mainland coastal areas and increased in numbers throughout its original range. Comparable movements are known to have taken place in South Australia. This expansion has apparently been in response to land clearance and the establishment of cereal cropping. Galahs are ground-feeders, and readily forage on wheat fields, lawns, golf courses and cleared paddocks.
The Galahs has thus shown itself able to respond quickly to an increased and more widespread food resource because of its natural mobility (itself an adaptation to the unpredictable nature of the climate of inland Australia). Large flocks move great distances in search of more favourable conditions when drought occurs in the interior. The Galah has been able to establish apparently permanent breeding populations as a result of such movements wherever the artificial habitats it encountered suited the needs of an open-country, seed-eating cockatoo. Ian Bevege tells of a flock of Galahs that, in response to an inland drought in 1966, arrived at Maroochydore on the Sunshine Coast of Queensland, where they had not previously been recorded. The birds remained to breed and founded what is now a permanent resident population. A similar story might be told of many places along the east coast, and the Galah is apparently continuing in a process of vigorous expansion and consolidation.
The Galah nests in a wide variety of tree hollows and competes actively with other species for available space. It usually selects a cavity from about two to twenty meters from the ground, but if a suitable hollow is not available, it will enlarge or create a suitable nest chamber. The floor of the chamber is carpeted with a few green leafy twigs. The clutch varies from two to six eggs which, incubated by both parents, hatch in about thirty days.
Galahs rarely breed until they are at leats two years old. Mating is permanent, but a new partner may be acquired after the death of one member of the pair. Although the birds may forage up to twenty kilometres away, mated pairs are sedentary, returning every night to roost near the nest-tree and using the same nest hollow year after year. The reproductive strategy of the Galah involves a long period when the young are dependant upon the parent birds, including up to two months’ residence in the nesting chamber before fledging. For thirty to forty days after departing the nest, adolescent birds form part of a crèche, which occupies tree tops or similar perches while the adult birds are out foraging. The parents return at intervals throughout the day to feed the young birds. When finally abandoned by their parents, juveniles form large flocks and disperse throughout the countryside. Adults seldom undertake these long-range movements unless prevailing environmental conditions force an emigration. There is a high death rate among younger birds but, if they survive into adulthood, there is a good chance they will live for many years. Analysing returns of tagged nestlings in Western Australia, Ian Rowley found that only forty-three per cent survived their first six months of life. Eighty per cent of all his returns had travelled less than twenty kilometres, and over half of the total had been shot. Remarking that “a population of galahs consists of three very different groupings; juvenile flocks that wander extensively; immature flocks that are locally nomadic; and the resident breeding pairs”, he concluded that “shooting accounts for most galah deaths in the Western Australia wheatbelt, with cats, raptors and motor vehicles as other major factors; a quarter of the young birds that leave the nest may die before they are deserted by their parents after 6 weeks”.
The Galah has hybridised with other cockatoos both in the wild and in captivity. There are also records of aberrant coloration in the wild, where the pink or the grey in the plumage is replaced by white. One aviary hybridisation involving a Sulphur-crested Cockatoo and a Galah took place under unusual circumstances between two very old birds kept by Jim Rook, of Griffith, New South Wales. The male Galah, at the age of at least forty years, tore through the wire separating him from the female Sulphur-crested Cockatoo to consummate the relationship. Expecting no progeny from such an unlikely pairing, Rook did not provide a nest box, but the Sulphur-crested female was undeterred and excavated a nest chamber underneath a piece of corrugated iron to lay two eggs, which subsequently hatched to produce a pair of spectacular “Cock-galahs”. These birds were orange underneath, with grey wings and a large crest similar to that of the Pink Cockatoo (Major Mitchell).
Francis Crome, James Shields (1992), Parrots & Pigeons of Australia
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