Favourable inland wetland conditions increase apparent survival of migratory shorebirds in Australia

ABSTRACT

Many migratory shorebird species using the East Asian–Australasian Flyway are declining rapidly. While the loss of staging habitats in East Asia is considered the primary cause, stressors to fitness often occur throughout the geographic range of declining species, and threats in the non-breeding grounds have been comparatively poorly studied. Three species of migratory shorebird, Curlew Sandpiper (Calidris ferruginea), Sharp-tailed Sandpiper (C. acuminata) and Red-necked Stint (C. ruficollis), use Australia’s dynamic temporary wetland systems opportunistically, yet these large wetland systems have become increasingly degraded, with reduced frequency and extent of flooding. Here, we test whether variables related to wetland availability in Australia’s interior can explain annual variation in apparent survival, abundance or immature to adult ratios at three well-monitored coastal shorebird areas in southern Australia (total area > 1315 km²). We show that coastal annual bird abundance and ratios of immatures at the coast were higher when inland Australia was relatively hot and dry. Also, a small but significant amount of variation in annual apparent survival can be explained by annual variation in inland conditions, with higher survival rates in years when inland conditions were relatively wet and cool. For the endangered Curlew Sandpiper, the impacts of Australian environmental conditions may be exacerbating the impacts of conditions experienced in other parts of its range on fitness and survival. While the effects we document here are relatively weak, they do suggest that management of inland wetlands for these shorebirds may positively affect survival rates of these sharply declining species.

KEYWORDS:

• Shorebirds
• temporary wetlands
• apparent survival
• Australian birds

Acknowledgements

This paper is dedicated to the memory of Clive Minton and Ken Rogers, our co-authors whose leadership provided the foundation of this work and many shorebird studies. This work was made possible due to an enormous long-term commitment by volunteers from the Victorian Wader Study Group, whose banding efforts over 30 years allowed us to estimate annual apparent survival, and by the many volunteers who provided count data. We would also like to thank the Australasian Wader Studies Group, and BirdLife Australia (http://birdlife.org.au/projects/shorebirds-2020) for providing the count data. We are grateful for the long-term support of shorebird monitoring from Melbourne Water (Western Treatment Plant) and Parks Victoria (Corner Inlet). For the data on environmental variables we would like to thank the agencies who have made quality data easily available, including: the Bureau of Meteorology, the CSIRO and Geoscience Australia. This work was funded by Linkage grant LP150101059, supported financially by the Burnett Mary Regional Group for Natural Resource Management, the Queensland Department of Environment and Heritage Protection, and the Queensland Wader Study Group. We also acknowledge the generous support given to Robert S. Clemens through the Stuart Leslie Bird Research Award and BirdLife Australia.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Centre of Excellence for Environmental Decisions, Australian Research Council [LP150101059].