Final report, June 2017. Report prepared for the Commonwealth Environmental Water Office by K. Brandis Centre for Ecosystem Science, University of New South Wales
About the document
Waterbirds in the Macquarie Marshes made the most of very good conditions between July 2016 and February 2017, when environmental water was used to support successful waterbird breeding.
The Commonwealth and NSW governments used a total of 46,413 megalitres of water in the Marshes to address two priorities for 2016-17: supporting waterbirds by watering their critical breeding and feeding habitat, and seizing opportunities to build on natural flows to support waterbird breeding.
The University of New South Wales conducted short-term monitoring on behalf of the Commonwealth Environmental Water Holder to assess waterbird breeding success at the Monkeygar and Zoo Paddock areas of the Marshes, where straw-necked ibis, glossy ibis and royal spoonbills were observed breeding.
The university’s key observations were:
- Reproductive success was around 65 per cent for early nesting straw-necked ibis, similar to other colonies that were recorded breeding in the Murray-Darling Basin in 2016.
- Environmental water delivered to Monkeygar in late January 2017 maintained water levels in the colony, which supported late nesting royal spoonbills and provided foraging habitat to fledged ibis.
- Late-nesting straw-necked ibis, glossy ibis and royal spoonbill colonies at Zoo Paddock suffered significant losses (more than 80 per cent) from ground-based predators. The birds became easy prey as floodwaters receded, and it was not possible to deliver environmental water to maintain water levels.
- Avian botulism, a naturally occurring disease, was also likely to have contributed to the mortality rates estimated for colonies at Monkeygar and Zoo Paddock.
The short-term waterbird monitoring project has provided valuable information on how environmental watering can enhance waterbird breeding outcomes by maintaining water levels within colonies during breeding, and by maintaining important foraging habitat during and between breeding events. The information collected will assist future watering decisions in the Macquarie Marshes and at other important waterbird locations across the basin.
Left: Monkeygar Swamp. Right: Royal spoonbill chicks at Zoo Paddock. Photos: Emily Webster (UNSW)