Dynamics of the waterbird fauna of Peery Lake, arid north-western New South Wales, after flooding

Waterbirds were surveyed at the north-western end of Peery Lake, a large freshwater overfl ow lake on the Paroo River, between October 1990 and January 1994, following a major fl ood that fi lled the lake in April 1990. Before drying, the lake was recharged by a moderate fl ood in January 1993 and retained water throughout the study. The survey area comprised about 555 hectares or 11 percent of the lake, plus the adjacent shoreline. Over nine survey periods, a total of 54 waterbird species was recorded, of which eight species were recorded breeding, although only in low numbers. Species richness in individual survey periods ranged between 17 and 42 species. The number of waterbirds in the survey area varied greatly between survey periods, from 636 to 14 359. Two species, Pink-eared Duck Malacorhynchus membranaceus and Grey Teal Anas gracilis, accounted for about 60 percent of all waterbirds, but the common species varied between survey periods. The responses of waterbirds to the two fl ood events were markedly diff erent. Waterbird numbers were initially low after the fi rst fl ood, peaking 27 months after fl ooding. By contrast, waterbird numbers were high in the fi rst year after the second fl ood, but fell sharply 12 months after fl ooding. The abundance and diversity of waterbirds recorded on this small portion of Peery Lake affi rmed the lake’s importance to waterbirds. The study also showed the dynamic and highly variable nature of the waterbird fauna, whose response to particular fl ood cycles at the lake can diff er widely and cannot be predicted by simple measures such as the size and salinity of the lake.

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