Australia: Big fall in number of migratory seabirds as rising sea covers vital mudflats

Peta Gilbert Sydney Morning Herald 18 Dec 16;

Birds migrating from the Arctic to Botany Bay for the summer months are dwindling in number due to increasing coastal development and climate change, according to experts.

Philip Straw, an environmental consultant on waterbirds and wetlands, said migration has decreased in the Botany Bay area by more than 40 per cent.

"Some species, like the eastern curlew and curlew sandpiper, have declined by up to 80 per cent," he said. "We need to protect this site because it is so important to the migratory shorebirds."

The construction of a third runway for Sydney Airport and the expansion of Port Botany in 2014 has meant less coastal areas for these endangered birds to roost, he said.

Director of the Centre for Ecosystem Science Richard Kingsford said bird numbers have fallen from 2000 in the 1970s to fewer than 1400 today.

"We have data that has been collected since 1944 and we've been able to monitor the numbers of these birds," he said. "It's developments like the Port Botany expansion that destroy yet another area where migratory birds are declining."

During the Port Botany Expansion, to compensate for the removal of some of the habitat, Sydney Ports renovated and improved areas for the birds, however Professor Kingsford is sceptical that this action mitigated the removal of the birds' original habitat.

Climate change also poses a threat, with the birds feeding on low-lying mudflat areas that are increasingly covered by rising sea levels.

"The problem with living in a city like Sydney is that there is limited space, if sea levels rise and encroach we can't push the whole city back, there is limited space to work with in the first place," Professor Kingsford said.

The area, which has been deemed a "wetland of International Importance" for more than 40 years, hosts about 35 species of migratory birds who stay in Botany Bay from September to April each year.

"The birds rely on this area of Towra Point Reserve, particularly when they need to fly home because in order to 'fuel up' they need to put on 60 per cent of their body weight in fat," Mr Straw said. "If there's no land to feed on, they won't have developed enough fat storage meaning they won't attempt the journey home and as a result they don't breed."

According to Mr Straw, joint studies in Botany Bay by BirdLife Australia and NSW National Parks and Wildlife Service have raised concerns about habitat for migratory birds.

Along with a number of other environmental consultants, Mr Straw is hoping to complete a study in 2017 on behalf of the federal government regarding potential solutions to restore the area and prevent any further decline in numbers.