2023
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About the reports
Wet conditions created optimal circumstances for waterbird breeding across the Murray-Darling Basin in 2021-22 and into 2023.
The Commonwealth Environmental Water Holder engaged the University of New South Wales (UNSW) to undertake waterbird monitoring at specified sites in the Northern and Central Basin catchments to better understand:
- triggers of waterbird breeding at different sites throughout the Basin
- reproductive success of waterbirds at breeding sites, and
- comparisons between populations across the Basin.
Key findings from the reports include:
- At Dharriwaa-Narran Lakes the total nest counts for the Lignum Swamp and South Arm rookeries the 2022-23 season were approximately ~7,334 straw-necked ibis nests, in addition to breeding by Australian white ibis, glossy ibis, royal spoonbills, egrets (intermediate and great egrets) and cormorants (little black and great cormorant). Total Australian pelican nests at Black Box rookery to March 2023 was ~19,688 nests which was amongst the largest in the Basin during 2022-23.
- In the Gwydir wetlands during mid-late November 2022 straw-necked ibis began nesting at Goddard’s Lease Ramsar site, along with at other rookery sites in the Gingham and one site in the Lower Gwydir. The Goddard’s Lease ibis rookery was smaller in 2022-23 (~4,000 nests) than in 2021-22 (~11,700 nests). Only one of the eight large aggregating waterbird rookeries was able to be monitored using drone surveys in 2022-23.
- The Lower Lachlan accounted for ~44% of all straw-necked ibis nests counted in the Murray-Darling Basin in 2022-23. Total drone derived nest counts for the Lower Lachlan were 171,137 straw-necked ibis nests and 2,218 Australian white ibis nests. This included the largest rookery ever recorded at the Booligal Block Bank with 144,947 straw-necked ibis nests within an estimated 122 ha maximum rookery boundary (2nd March 2023).
- A total of nine surveys were completed in the lower Murrumbidgee, consisting of nest and drone surveys between October 2022 – March 2023. The Bala Rookery was the second largest single rookery site in the Murray-Darling Basin during 2022-23 with 98,830 straw-necked ibis nests, or ~26% of all straw-necked ibis nests counted in the Basin in 2022-23. The Bala Rookery was a mixed species rookery, with observations of breeding by Australian white ibis, little pied cormorants, great black cormorants, and royal spoonbills.
- In the Macquarie Marshes rookery mapping and nest counts from drone surveys was successful with >107,000 nests counted across the three rookeries, total nest counts were generally comparable to those in 2021-22 of >116,000 nests across four colonies. At a rookery scale T-block was larger in 2022-23 while Monkeygar North was smaller.