Vanishing act leaves sitting ducks on top
Dominant ... Pacific black ducks in Centennial Park. Richard Kingsford of the University of NSW says other species headed west. Photo: Lee Besford
IF THERE was a hierarchy governing Centennial Park's waterbirds, the Pacific black duck would rule supreme. They have long been the most common species inhabiting the park's 12 ponds and, after the wet summer, their dominance is growing.
Many of the nomadic waterbirds that seek refuge in the park during drought deserted the sanctuary after last year's floods and headed west to chase the rich wetlands of the outback.
''We've certainly seen a lot fewer of species like the hardhead and grey teal over the past year,'' the director of the Australian wetlands and rivers centre at the University of NSW, Richard Kingsford, said. ''Conditions are so fantastic out west at the moment.''
The wandering natives do not breed in city parks and flocked inland where the floods produced ideal conditions.
Some species vanished from the city parks entirely but Graeme Robinson, who has been birdwatching in Sydney for about 25 years, said they are starting to return with a new generation.
''They've had a breeding episode and taken advantage of the floods and the population is starting to head back into the city,'' he said. ''In one way, the flooding has actually helped to preserve the urban population by allowing them to breed.''
The Pacific blacks do occasionally turn nomadic after floods and some of the young ones may have headed off after being kicked out of the nest but most stayed put.
The ducks have water, food and safe breeding grounds at Centennial Park and they populate the ponds year-round.
''It has been a very good breeding year for the resident birds - like the swans and the black ducks - and their numbers have come up quite well,'' Mr Robinson said.
Pacific black ducklings and black swan cygnets were spotted at Centennial Park over the weekend, which is unusual this late in the season. They commonly breed in spring but with the right conditions they can breed in autumn. This often occurs after the onset of heavy rain and recent downpours are likely to have had a positive impact on the park's resident waterbirds.