Effect of river management on colonially-nesting waterbirds in the Barmah-Millewa forest, south-eastern Australia
✍ Scribed by Leslie, David J.
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 182 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0886-9375
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✦ Synopsis
River management has affected the ability of colonially-nesting waterbirds to reproduce in the Barmah-Millewa forest, south-eastern Australia. Relationships between reproductive performance and flow variability were quantified in order to establish the significance of the impact. The method of investigation involved: developing a conceptual framework describing four breeding-flow relationships (excellent, poor, abandoned and nil); obtaining measures for each relationship using annual breeding records (19 years; 1979-1997), habitat data (two traditional nest sites, one foraging area) and flow data (Murray River at Yarrawonga); and testing their predictive power at a landscape level. The effect of river management on the reproductive performance of colonially-nesting waterbirds was then assessed. Annual pulse dimensions in two runs produced by the monthly simulation model (natural and current flow; 1891-1992) were compared with the breeding-flow measures to obtain computer generated breeding level predictions. A major impact of river management was an 80% reduction in the frequency of successful breeding episodes compared to the natural precedent. The interval between breeding episodes during extended drought periods was identified as the most critical factor likely to affect the long-term stability or persistence of waterbird breeding in the forest. A literature review provided evidence of declining abundance and diversity of colonially-nesting waterbirds, and gave insight to the timing and factors contributing to the decline of many species. The principal conclusion is that three river flow objectives need to be addressed to ensure the long-term stability or persistence of breeding populations in the forest.