Satellite telemetry reveals complex mixed movement strategies in ibis and spoonbills of Australia: implications for water and wetland management

Abstract

Waterbird population and species diversity maintenance are important outcomes of wetland conservation management, but knowledge gaps regarding waterbird movements affect our ability to understand and predict waterbird responses to management at appropriate scales. Movement tracking using satellite telemetry is now allowing us to fill these knowledge gaps for highly mobile waterbirds at continental scales, including in remote areas for which data have been historically difficult to acquire. We used GPS satellite telemetry to track the movements of 122 individuals of three species of ibis and spoonbills (Threskiornithidae) in Australia from 2016 to 2023. We analysed movement distances, residency periods and areas, and foraging-site fidelity. From this we derived implications for water and wetland management for waterbird conservation. This is the first multi-year movement tracking data for ibis and spoonbills in Australia, with some individuals tracked continuously for more than five years including from natal site to first breeding attempt. Tracking revealed both inter- and intra-specific variability in movement strategies, including residency, nomadism, and migration, with individuals switching between these behaviours. During periods of residency, areas used and distances travelled to forage were highly variable and differed significantly between species. Sixty-five percent of identified residency areas were not associated with wetlands formally listed nationally or internationally as important. Tracking the movements of waterbirds provides context for coordinated allocation of management resources, such as provision of environmental water at appropriate places and times for maximum conservation benefit. This study highlights the geographic scales over which these birds function and shows how variable waterbird movements are. This illustrates the need to consider the full life cycle of these birds when making management decisions and evaluating management impacts. Increased knowledge of the spatio-temporal interactions of waterbirds with their resource needs over complete life cycles will continue to be essential for informing management aimed at increasing waterbird numbers and maintaining long-term diversity.