Wetlands Australia 33: Migratory shorebirds and artificial roosts

Authors: Amanda Lilleyman, Micha Jackson and Jaana Dielenberg, Threatened Species Recovery Hub, National Environmental Science Program.

Many ‘working coastal wetlands’, including ports, commercial salt works and wastewater treatment plants, host important habitat for threatened migratory shorebirds. Although artificially created, these areas can be attractive high tide roost sites for shorebirds, particularly when the area is closed to the public.

Migratory shorebirds undertake some of the most incredible migrations on earth and are in serious decline globally. Around the world, multiple threats are impacting migratory shorebirds throughout their lifecycles. One of the most significant threats in Australia is disturbance – especially at high tide roosts.

A lack of roosts that are safe from disturbance may even constrain the number of shorebirds that a given region can support. A common cause of disturbance is people and their dogs using beaches for recreation.

Disturbance causes shorebirds to expend extra energy keeping watch and fleeing by walking or flying instead of just resting or feeding. The consequences are often underappreciated, but can be significant, resulting in reduced weight gain – weight that is vital to enable birds to complete long migrations back to their northern hemisphere breeding grounds.

Shorebirds flee from people walking their dog on a Darwin beach. Photo: Amanda Lilleyman.

Scientist Dr Micha Jackson from the University of Queensland has undertaken an international study on the high tide habitat use of coastal shorebirds. ‘In Australia there are several very important migratory shorebird roosting sites that have been artificially, usually unintentionally, created. While these sites should not be considered a replacement for natural habitat, a number of studies have shown that due to their lack of disturbance artificial habitats can provide attractive high tide roosts.’

Darwin Port is a prime example of such a site. Charles Darwin University researcher Dr Amanda Lilleyman has been monitoring Far Eastern Curlews at the artificially created East Arm Wharf Settling Ponds within the busy port.

‘The settling ponds are a very important roosting site for the Far Eastern Curlew and many other migratory shorebirds. We found that the site sometimes holds close to 1% of the global population, making the port a site of importance for the critically endangered species,’ Dr Lilleyman said.

Protecting habitat and understanding how artificial sites fit within a network of natural sites is an important aspect of conserving threatened shorebird species alongside coastal development.

Far eastern curlew. Photo: Micha Jackson.