A plan for protecting migratory shorebirds in Darwin Harbour warns that development, including the controversial Middle Arm industrial precinct, could have a detrimental effect on the coastal bird habitat, also recommending barrier fencing using a floating buoy line on a section of Lee Point beach.

The Darwin Harbour migratory shorebird site action plan was developed by shorebird experts from BirdLife Top End, Dr Amanda Lilleyman and Gavin O’Brien, and launched on Monday night, with its main stated objective to protect, conserve and, where necessary, improve key roosting and feeding habitats at Darwin Harbour for long-term use by migratory shorebirds.

It states the issues and threats relevant to migratory shorebirds at Darwin Harbour include anthropogenic disturbance, habitat modification and coastal development, volunteer burn-out, volunteer recruitment, and a lack of coordinated management across stakeholder groups.

The authors state the plan is structured to address the objectives of reducing or eliminating human and introduced threats to the birds, maintaining and protecting key habitats, developing fast tracked management responses, and increasing communication, education, participation and awareness programs about migratory shorebird conservation.

“The community values migratory shorebirds and we have an obligation to protect birds that visit Darwin Harbour,” Dr Lilleyman said in a statement.

“Volunteers have highlighted the need to manage and conserve shorebirds, particularly in the Casuarina Coastal Reserve, for decades.

“Countless media articles have demonstrated the chronic threatening processes to shorebirds, yet there have been no strategic management actions taken. It is now time to prioritise the shorebirds so they can keep coming back to our shores.”

The plan states Darwin Harbour is undergoing substantial coastal development as an international gas export hub, and while developments must meet national environmental standards by law, large scale coastal development, clearing of mangroves, and inappropriate dredging of the intertidal zone, all threaten the availability of habitat for migratory shorebirds.

“There is a range of groups that are working to ensure that any coastal development in Darwin Harbour is sensitive to important biodiversity areas and habitat used by significant populations of wildlife, such as shorebirds,” the plan said.

The Lawler Government’s proposed Middle Arm industrial precinct, which sits on Darwin Harbour, is backed by $1.5 billion in “planned equity” from the Federal Government to support the construction of common user marine infrastructure. It has four companies interested so far, that have been allocated free land at the proposed site, with plans for a gas export plant, a green hydrogen production plant, a plant to manufacture pre-cursor battery cathode materials from critical minerals, and a critical minerals processing plant.

The planned use of that industrial area is the subject of a Senate Inquiry, investigating federal funding for the gas and manufacturing hub, the environmental impacts of the proposal, as well as who is benefiting from the project.

The shorebird action plan says Darwin Harbour has several sites that are internationally and nationally important for migratory shorebirds, with migratory shorebird species continuing to decline globally while facing many threats along migratory flight paths, known as flyways.

The plan describes two main areas of focus, with one centred on Charles Darwin National Park, stretching from the east side of the Darwin central business district around Frances Bay to the East Arm wharf area, which sits across from Middle Arm at the mouth of the Elizabeth River.

The other area is located on the Beagle Gulf coastline of the Timor Sea, based around the coastline to the north of the Darwin CBD, starting at East Point and continuing to Gunn Point east of the Shoal Bay area.

“While Lee Point supports more roosting migratory shorebirds than the other shorebird sites, some sites in Darwin Harbour still support more than 30 per cent of the total Darwin Harbour waterbird population,” the plan says.

“As there is a lack of available roost sites for shorebirds during high tides above 7.4 metres, artificial roost sites are becoming particularly important: during the highest tides, over 80 per cent of the local Darwin Harbour population of [the critically endangered] far eastern curlew now roost at East Arm Wharf, close to one per cent of the global population of this species.”

The plan also says disturbance to the birds was a key threat that had persisted in the Darwin Harbour region for more than two decades.

“One study on disturbance to shorebirds recorded most disturbances in Darwin Harbour at the two natural sandy-beach sites (Lee Point and Sandy Creek) which have also historically supported the highest number of birds from across the surveyed sites in Darwin Harbour,” the plan said.

“Humans (with or without dogs) made up over 70 per cent of disturbances across the sites. The natural sandy beach at Lee Point has high levels of disturbance that are sometimes sufficient to cause biologically significant energetic cost to sand plovers and knots roosting there.”

One of the high priority recommended actions was to establish and maintain regular coastal zone patrols using regulatory officers or local Indigenous rangers to look for non-compliance issues such as dogs, boats and airboat disturbances, as well as to install barrier fencing using a floating buoy line at Lee Point beach at the beginning of the no-dog section of the beach.

Significant regional declines in birds that visit Darwin

Migratory shorebirds, or waders, are a group of birds that can be found feeding on swamps, tidal mudflats, beaches, and open grasslands, the plan said, which make an annual return journey of up to 25,000km between their breeding grounds in the northern hemisphere and their non-breeding grounds in the southern hemisphere.

Australia is part of the East Asian-Australasian Flyway, which extends from breeding grounds in the Russian tundra, Mongolia, northern China, and Alaska through east and south-east Asia, to non-breeding areas in Indonesia, Papua New Guinea, Australia and New Zealand.

The plan says that on southern migration, shorebirds that migrate from the northern hemisphere reach “staging areas”, such as Roebuck Bay and Eighty-mile Beach in northwest Western Australia and the Gulf of Carpentaria in Queensland, by September. And from there they disperse across Australia, reaching the south-eastern states by October.

BirdLife Australia’s migratory shorebird plans focus on the 37 migratory shorebird species on that flyway that regularly visit Australia, and are thus listed under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) as “migratory species”.

The report said the flyway has seen significant regional declines have been identified in at least 18 species, and in May 2015, the far eastern curlew and curlew sandpiper were listed as critically endangered under the EPBC Act.

“Coastal development at staging and non-breeding grounds throughout Asia and Australia poses the most significant threat to the majority of the 37 species that regularly visit Australia,” the plan said.

BirdLife Top End says Darwin Harbour is critical to shorebirds with many beaches and coastal areas supporting internationally significant populations of birds, including the great knot, greater sand plover, far eastern curlew, and the common greenshank.

The plan said that in the month or two before migrating, migratory shorebirds need to increase their body mass by up to 70 per cent to sustain their journey.

“After their first southward migration, many juvenile birds often remain in Australia until they reach approximately eighteen months of age when they embark on their first northward migration.

“…Many shorebirds remain in northern Australia for the austral summer season (build-up and wet seasons).

“…By March, the birds that have previously dispersed across the country begin to gather at staging areas, once again forming large flocks and feeding virtually round the clock to accumulate the energy reserves that are required for their northward migration.”