Macquarie Marshes Colonial Waterbird Reproductive Success Monitoring 2022

2022
K. Brandis, G. Bonsen, E. Wooster, C. Hasselerharm, L. Juilliard, R. Francis

Report to the Commonwealth Environmental Water Office

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About the document

The Macquarie Marshes is one of the Murray–Darling Basin’s most biologically diverse wetland systems and have supported some of Australia’s largest recorded colonial waterbird breeding events.

In 2021–22, above average rainfall and river flows resulted in widespread flooding in the Macquarie Marshes, which triggered the first large-scale colonial waterbird breeding event in the Marshes since 2016–17.

The Commonwealth Environmental Water Office contracted the University of New South Wales to monitor the success of colonial waterbird breeding at four large colony sites in the Macquarie Marshes.

The monitoring project aimed to measure the reproductive success of colonial waterbird species in the Macquarie Marshes, monitor water levels and water quality in the colony sites and to monitor for disease, predation, and mass mortality.

Key findings from the project included:

  • Colony surveys found that stages of nesting and chick development was variable within and between colonies.
  • Reproductive success in the colonies reflected the variable stages of nesting observed during surveys (eggs through to runner stage chicks) with success ranging from 55% - 100% across different chick development stages.
  • There were no observations of significant disease or mass mortality.
  • Water levels in the colonies were stable throughout the breeding period with no evidence of nest desertion or significant predation.
  • Meeting the requirements of inundation duration, water depth and timing of flows are critical components of water management that play a key role in ensuring colony success.
  • The support of colonial waterbird colonies through the provision of environmental water is critical in the conservation of these species, limiting populations declines.

This monitoring project provides valuable information on colonial waterbird breeding and the role of water for the environment in supporting colonial waterbirds. This information will help inform the future delivery of water for the environment to the Macquarie River and Marshes.

Further information