Tracking juvenile Great and Plumed Egrets movements from the Macquarie Marshes
Egrets breed in large numbers at inland freshwater wetlands and are ‘obligate wetland-feeders’, dependent on and specially adapted for eating foods that live in surface water. Understanding their movements is critical for conserving their populations, protecting their habitats, and ensuring the overall health of ecosystems they inhabit.
The Challenge
“Yurru” the juvenile plumed egret
As Egrets are obligate wetland feeders this makes them sensitive to changes in wetland habitats and a good indicator species for the health of inland wetlands.
Understanding egret movements is critical for conserving their populations, protecting their habitats, and ensuring the overall health of ecosystems they inhabit. Learning where, when and how egrets move will help to identify critical routes and sites for habitat protection and resource prioritisation, as well as potential threats and risks such as habitat destruction, pollution, disturbance, or climate change impacts.
Understanding egret movements is challenging because they breed and move through large areas and very remote parts of the continent. They are also difficult to capture because they usually breed in trees. Fine scale movement tracking using satellite technology is needed to understand their life cycle, but has never been undertaken in Australia before.
Our Response
CSIRO’s waterbird movements research led by Dr Heather McGinness began in 2015-2016, with GPS satellite trackers first deployed as part of the MDB EWKR (Murray-Darling Basin Environmental Watering and Knowledge Research) Project. Additional trackers have been deployed in most years since then, with the range of sites and species expanded with support from the CEWH Monitoring, Evaluation and Research program (Flow-MER) and other projects, and the Lake Cowal Conservation Centre.
For a variety of reasons, tracking efforts have focussed largely on Straw-necked ibis Threskiornis spinicollis Royal spoonbills Platalea regia. However, the unusually wet summer of 2022-2023 triggered extensive breeding of aggregate-nesting waterbirds, including egrets, at the Macquarie Marshes (NSW), a semi-arid floodplain that is one of the most important wetlands in Australia for aggregate-nesting waterbirds. This, combined with the relatively unusual occurrence that some egret breeding occurred low in shrubs rather than high in trees, provided a good opportunity to catch Great Egrets Ardea alba and Plumed Egrets Ardea plumifera and attach satellite transmitters to learn more about their movements.
The Results
The waterbirds team deployed GPS satellite transmitters on 10 juvenile great egrets and 8 juvenile plumed egrets in early 2023 and tracked their movements from their natal sites in the Macquarie Marshes. This is providing valuable new information about dispersal patterns and long-distance movements.
Initial tracking results indicate clear species differences following dispersal from the heronries including direction of dispersal and dispersal distance. There were some notable areas used by multiple individuals and both species as stopover sites for resting and foraging during dispersal, which helps to identify particularly important sites for supporting juvenile egrets into adulthood.
One tracked great egret provided a particular surprise. Following capture at the Macquarie Marshes in February 2023, it travelled northward between March and May of 2023 before departing the continent and travelling to Papua New Guinea during an approximately 38 hour non-stop flight! It remained in PNG for at least several months following this astonishing journey.
Several egrets are still actively transmitting data and our team is currently working to analyse multiple aspects of egrets movements based on the tracking data from all of the egrets tracked from the Macquarie Marshes.
Yurru’s Journey: Tracking the Migration of a Juvenile Plumed Egret
Curious about how far Yurru has travelled across Australia? Watch the video below to see the detailed movements of Yurru as they journey through various regions of the country, captured between February and July 2023.
Yurru’s Migration Path (2023)
Find Out More
The waterbirds team is always looking for opportunities to collaborate with land and water managers to track additional inland waterbirds so we can learn more about their ecology, better understand habitat requirements, and thereby improve decision-making, effective management practices, and the development of targeted conservation strategies.
You can learn more about the CSIRO waterbirds project including satellite tracking of other species and our suite of research activities from our project website. You can also find animations of tracked waterbirds on our YouTube channel.
If you’d like to be added to our periodic email updates, please contact Heather McGinness.
