Oral Presentation Australian Freshwater Sciences Society Conference 2024

Satellite-tracked post-natal movements of juvenile egrets from the Macquarie Marshes (112570)

Heather M McGinness 1 , Luke Lloyd-Jones 2 , Freya Robinson 1 , Louis O'Neill 1 , Shoshana Rapley 1 , Xinyu Hou 1 , Micha V Jackson 1
  1. Environment, CSIRO, Black Mountain, ACT, Australia
  2. Data 61, CSIRO, Dutton Park, QLD, Australia

Egrets breed in large numbers at inland freshwater wetlands alongside other aggregate-nesting waterbirds like ibis and spoonbills. They are ‘obligate wetland-feeders’, meaning they are dependent on and specially adapted for eating foods that live in surface water. 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. Finescale movement tracking using satellite technology is needed to understand their life cycle but has never been undertaken in Australia before. We deployed GPS satellite transmitters on 18 juvenile egrets of two species: great egret (Ardea alba; n = 10) and plumed egret (Ardea plumifera, n = 8) and tracked their dispersal movements from their natal sites in the Macquarie Marshes, New South Wales, Australia. Here we describe dispersal patterns, which differed significantly between species, and an extraordinary international movement made by a juvenile great egret. We will also consider some implications for water management.