Migratory shorebird ecology in the Hunter estuary, sourth-eastern Australia

• Main Author: Spencer, Jennifer
• Format: Thesis
• Language: unknown
• Published: Australian Catholic University 2010
• Subjects: Arctic
• Online Access: https://acuresearchbank.acu.edu.au/download/1bdcaf2a2dcfc577fc42829166597aa52a668ca6363ed3f997106328c591c27e/12900566/65093_downloaded_stream_318.pdf; https://doi.org/10.4226/66/5a95f64bc682a

Migratory shorebirds inhabit the shorelines of rivers, wetlands, oceans and lakes, where they need to rest and feed during their non-breeding seasons to prepare for their annual migrations to breeding grounds in the Arctic. Along their flyways many non-breeding and stop-over sites are under pressure from coastal developments, disturbance, global sea level rise and water resource development. In this thesis I investigated how migratory shorebirds responded to habitat loss in the Hunter estuary, a non-breeding site in south-eastern Australia, and how they used remaining estuarine habitats. The Hunter estuary is a wetland of international importance but has a long history of modification from industrial and urban development which began in the late 1800s. Based on recent counts (2001-07), the Hunter estuary now only supports two species in internationally significant numbers (Eastern Curlews Numenius madagascariensis and Sharp-tailed Sandpipers Calidris acuminata) compared to seven species listed from earlier records (1970-90). Overall, I detected a 42% decline in total numbers of migratory shorebirds (1981 - 2007) in the estuary, with significant declines (44 - 83%) in four species. The tidal cycle was the main driver for the distribution of shorebirds in the Hunter estuary with most species feeding in exposed intertidal mudflats at low tide and being forced to rest at high tide. Eastern Curlews roosted on artificial structures and sandbanks during the day but at night they moved to flooded saltmarshes. Shallow water was important at the roost sites, as it provided a mechanism for cooling on warm days and for detecting predators at night. Vigilance behaviour made up 30 - 40% of Eastern Curlews roosting time, but vigilance increased by about 20% prior to their migration (Feb-Mar). Day roosting habitat was most limited during spring high tides and periods of high disturbance. Disturbance was significant at the day roosts (0.8 - 1.;7 hr-1), mostly from birds of prey, but Eastern Curlews spent longer in flight after ...