Will The Godwits Still Fly?

Will The Godwits Still Fly?

Bar-tailed godwits hit the headlines in New Zealand and around the world in 2007 when birds were tracked on a non stop migration flight from Alaska to New Zealand, covering at least 11,680 km in just eight and a half days.

But one of the world’s leading researchers of this global traveller has raised concerns that its long-term survival is threatened by habitat loss at key locations on its migration routes.

Brian J McCaffery, an American wildlife biologist who has studied the godwits in their breeding habitat on the Yukon Delta in Alaska, says godwit populations may already be vulnerable due to climate change, but habitat destruction is of more pressing concern.

Brian McCaffery will give a free public lecture titled “Godwits and their future” at 6.30 pm on Wednesday September 23, at the Department of Natural Sciences, Unitec, Auckland.

In March 2007, a female bar-tailed godwit was tracked by satellite during a 10,225km flight from the Firth of Thames to Yalu Jiang on the northern coast of China. It was recognised as the longest non-stop powered flight ever recorded for a non-seabird.

At the beginning of May, after five weeks refuelling on the mudflats of Yalu Jiang, that same bird – known by its leg-banding, E7 - took off and flew over 6000 km to a tundra breeding area in western Alaska. On August 30 E7 took off once again, leaving Alaska and making her 11,680km non-stop return flight to New Zealand, breaking the record she set in March.

Although scientists had suspected for several years that godwits could make such a long non-stop flight, the satellite data from E7 dramatically confirmed that hypothesis.

“We don’t know the exact status of the bar-tailed godwit population,” says McCaffery. “Is it stable, increasing, or declining? What we do know is that godwit habitat is threatened throughout their migration routes.”

To sustain their colossal migration flights, godwits need abundant food throughout their annual cycle. The birds depend on southern hemisphere tidal flats for the resources required to moult and store fat prior to northward migration.

Because they can only feed when the flats are exposed at low tide, they need secure places to roost when the tide is full. This roosting habitat is just as important as food.

They then require staging sites, long-term refuelling stations, along the way. The vast tidal flats of the Yellow Sea region are particularly important, because they stop there to refuel before completing their trip back to their breeding sites in Alaska. In this way godwits link vital places throughout the Asia-Pacific region.

It also makes then vulnerable.

Although the Yellow Sea region supports millions of shorebirds each year, it is subject to enormous pressures from human activity.

“Pollution, reduced freshwater flow and extensive reclamation projects are radically degrading and eliminating large expanses of precious wetland habitat,” says McCaffery.

The most striking – and perhaps notorious - example is the giant Saemangeum project in South Korea.

A 33km seawall completed in 2006 enclosed two entire estuaries, destroying 41,000 ha of intertidal habitat that was once used by flocks of over 400,000 shorebirds during northward migration.

For at least one species the effect of this has been dramatic. Bird counts between 2006 and 2009 at staging sites in Korea and China, as well as wintering sites in northwestern Australia reveal that over 60,000 great knots cannot be accounted for. As Saemangeum had once been a major staging site for this species, researchers believe the missing birds are gone from the population.

But habitat degradation and loss also threatens birds in New Zealand and Australia.

The unnatural expansion of mangroves as a result of decades of farming practices in the catchments of most harbours and estuaries in northern New Zealand has meant habitat loss for shorebirds.

The godwits are also currently subject to subsistence harvesting by indigenous people in Alaska.

“The species is harvested by Yup’ik Eskimos in Alaska and, at least in recent decades, by rural residents in China,” says McCaffrey.

“In addition, a legalised harvest was recently proposed in New Zealand by Maori.

“Unlike the vast body of scientific knowledge concerning the impacts of harvest on waterfowl, however, harvest management in shorebirds is limited to just a handful of species, none of which span the globe like Bar-tailed Godwits.

“The potential impact of harvest on large-bodied, long-lived shorebirds is not known, but the recent history of several other species (e.g. Eskimo Curlew, Slender-billed Curlew) suggests that depleted populations do not readily recover,” he says.

In addition, possible changes to the tundra ecosystem as a result of global climate change are already being identified.

For example, earlier emergences of the insect populations which provide shorebird food may upset the timetable of birds that need to time their nesting for periods of maximum food availability. Long-term shifts in weather patterns in the northern Pacific may further upset migration strategies that are heavily dependent on favourable winds.

Ultimately the difficulty with godwits is their dependence on habitat along migration routes extending 30,000 km. If the population is being negatively impacted, it may take several years before the decline in numbers is noticed. Then it becomes a question of identifying the source of the problem, or problems.

Addressing the threats posed by habitat loss and harvesting McCaffery says: “A management planning effort should be initiated that explicitly recognises the need for international cooperation, respects national bird conservation priorities and legislation, and formally seeks and incorporates input from all stakeholders - including in particular those indigenous peoples throughout the flyway who have strong socioeconomic and cultural investment in the species.”

Brian McCaffery will give a free public lecture titled “Godwits and their future” at 6.30 pm on Wednesday September 23, at the Department of Natural Sciences, Unitec, Auckland.

Outlining his lecture, he says, “We now know much about the annual migration cycle of the bar-tailed godwit population breeding in Alaska and migrating to New Zealand and eastern Australia. But how secure is this migration system? What do we know about the population itself – is it stable or increasing or declining? How can we find out?

“What is then needed to secure the future for this population?”

Brian McCaffery will be in New Zealand and available for media interviews from Friday, September 18 to Sunday, September 27.

Contact Miranda Shorebird Centre

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