The six 'missing' birds are the white-breasted white-eye from Norfolk Island, whose disappearance was caused by rat predation; the western Victorian form of the pied currawong
and the hooded robin from the Tiwi Islands, both decimated by changes in fire management practices; the thick-billed grasswren from Mice Springs and the southern form of the star finch that once occurred from Townsville to northern NSW, which were both affected by overgrazing; and the spotted quail-thrush from the Mt Lofty Ranges in South Australia, which was driven to probable extinction by habitat fragmentation.
THE pied currawong has increased in abundance rather than decreased, and the species has been implicated in the decline of other native bush birds.
However, nest predation decreased significantly when pied currawongs were removed and the results suggest that predation on nests could be contributing to bird declines.
There is firm evidence, though, that pied currawongs spread weeds such as privet, and their greater abundance is not regarded favourably.
They found that the pied currawong
, emu, Australian magpie, satin bowerbird and black-faced cuckoo-shrike, were all tong distance seed dispersal agents.
Plants which are heavy nectar-bearers (such as small garden-size grevilleas) and fruit bearers (like blueberry ash) may encourage territorial birds such as noisy miners and pied currawongs