The flight of the godwits

They've been called the champion migrants of the bird world. A small bird with a jumbo jet range that flies the 12,000km from Alaska to New Zealand non-stop over 7-9 days each year - all in search of something to eat. Sally Kidson talks to ornithologist Rob Schuckard about the amazing bar-tailed godwit that visits the Nelson region each year.

The flight of the godwits

Next time someone complains about a long-haul flight to some far-flung part of the globe, tell them the story of the bar-tailed godwit.

Each year, before the Alaskan tundra starts to freeze, most of these medium-sized wader birds set off on an incredible journey that sees them fly non-stop to New Zealand.

They cover a breathtaking 12,000km in seven to nine days - all without snacks, drinks, in-flight entertainment or frequent flyer miles.

To help comprehend the time these birds are airborne, imagine a bird taking off when you leave for work on Monday morning. Now picture it still being in the air when you head back to work the following week.

It is a feat of endurance that makes the efforts of even ironmen Nathan Fa'avae and Steve Gurney seem mundane. If a human could cover a comparable distance, it would mean running faster than 70kmh for seven days without a break.

Ornithologist Rob Schuckard, along with other dedicated members of the local branch of the Ornithological Society, has monitored and counted bar-tailed godwits at their feeding points throughout the Nelson region for several years.

Schuckard owns a farm in the Marlborough Sounds but trained as an ornithologist in the Netherlands.

He says most of the other birds that migrate long distances around the globe make stopovers along the way, or feed during their trip across the Pacific, making the journey of the shy bar-tailed godwit one of a completely different magnitude.

They are, arguably, the champion migrants of the bird world.

"This organism is absolutely outstanding," Schuckard enthuses.

But all is not well in the godwit world. Their numbers are in steep decline, and the bar-tailed godwit population has crashed from 155,000 in the 1990s to about 90,000 today.

Declines have been observed in the top of the South Island, where numbers have fallen from 23,000 in 2001 to 13,000 in 2007.

"There's something seriously wrong with it," Schuckard says.

Which is why, one golden early winter morning, I find myself following Schuckard along a section of Farewell Spit.

Schuckard, barefoot despite a biting northerly, and a group of hardy Orthinological Society of New Zealand members are taking part in the annual winter bird count on the gargantuan stretch of sand.

The spit, with its rich tidal mudflats, is a favourite stopover for the godwits. It is protected because of its international importance as a feeding area for the godwits and other migratory shorebirds like the ruddy turnstone and the red knot.

About 9000 bar-tailed godwits, or 10 percent of the total worldwide population, spend the summer at Farewell Spit. An area is considered of international importance when 1 percent or more of the worldwide population is staging there.

Other areas the godwits favour are the Firth of Thames, Manukau Harbour and Kaipara Harbour. Good numbers are also seen in the Far North and near Christchurch, around Dunedin and at Awarua, south of Invercargill.

While most of the birds have left for their breeding grounds in Alaska at this time of the year, adolescent godwits - those up to three years old - can still be seen. Prominent endemic species like the pied oystercatcher, which breeds in South Island alpine areas in summer, also winter over on the spit.

The fact that oystercatchers move away in early spring, when the godwits move in, is an interesting "complementary relationship" between the species, Schuckard says.

In the Southern Hemisphere, a lack of competition from native birds makes rich resources available to sustain the godwits' marathon flight across hemispheres. In the Northern Hemisphere, it's thought that the birds started making their long flights after the last Ice Age, thousands of years ago, when the retreating ice made rich food resources available during the limited Arctic summer.

We hunker down against the wind and wait for high tide - when the birds move to the western side of the spit, making them easier to count. Schuckard says the way that godwits have evolved to travel long distances is "mindblowing".

Scientists have only a patchy idea of how high the birds fly, but it could be about 2000-3000m. A dead female godwit was once found on Mt Ruapehu, at 2200m, Schuckard says.

It's thought that the birds, which are believed to fly in small groups, fly at such an altitude to keep themselves cool.

Schuckard says one school of thought is that the ability to burn precious body fat to carry them across immense distances might not function at warmer, lower, altitudes.

Scientists also think the birds are able to shrink the size of their gut before they leave so they don't have to carry extra weight on their long flight.

"Basically, they get their body to an optimum before making this amazing journey."

The only water they get along the way is the byproduct of converting their body fat to fuel, he says.

When the migrants arrive in New Zealand, they are bone-thin, tired, hungry and bedraggled, just feathers and bones.

Despite this, the birds have little time for a break. They have to devote their energy intake to preparing themselves for the long journey back to Alaska.

Between October and December, they have to moult to replace their worn feathers. Between January and March, they eat and eat and eat, piling on the 30 to 40 percent fat reserves they need for their long flight back to the Northern Hemisphere to breed. They also change their plumage (but not their flight feathers) to the rusty brown colour seen before migration.

Schuckard says the birds are on a very tight schedule to get ready for their return journey, and they might not put on the necessary body weight for the trip if they are stressed if harassed by people, dogs, predators or other disturbances.

That's why it is critical that godwits and other vulnerable species have undisturbed access to their highly productive feeding areas in New Zealand and along the flyways, he says.

The Ornithological Society does counts to identify and monitor sites of international importance, including Farewell Spit.

While the spit is protected, the birds also roost at less recognised areas in the Nelson region, including Waimea Inlet and the Motueka Sandspit. But encroaching development is leaving less and less space for them.

Schuckard says a lack of management plans for the Motueka Sandspit and Waimea Inlet means these areas do not get the recognition they deserve. They are important, not just to godwits, but also to pied oystercatchers and other native species.

"The protection of these areas is abysmal."

Also of great concern is the condition of critical stopover areas the birds use in the Yellow Sea during their return flight to Alaska. Massive areas of estuaries in China, South Korea and Japan have been lost through land reclamation or pollution.

Last year, 40,000ha of rich tidal mudflats was drained for development at Saemangeum, South Korea in one hit. This is the same area as Farewell Spit, Manukau Harbour, Kaipara Harbour and the Firth of Thames combined.

About 200,000 shore birds, or 4 percent of the total 5 million migatory birds on that flyway, stopped at Saemangeum. The developers rationalised their actions by saying the birds could simply go somewhere else.

"The Yellow Sea is the central supply in the whole machine room. Two million shore birds migrate through there each year," says Schuckard.

Other major threats to the godwits are the loss of tidal areas to aquaculture, industry and salt works. The impact of climate change and changing weather patterns is as yet unknown.

However, collaborative ground-breaking research being done now could help to shed light on the vulnerable species and lead to greater protection.

Last year, for the first time, scientists were able to fit high-tech satellite transmitters to 16 godwits in Alaska and New Zealand and pinpoint their migration south and north along their flyway.

Two birds left Alaska on August 31, and were tracked for seven days before contact was lost with them south of Fiji on September 7.

It is thought that the transmitters' batteries failed during the flight. Both birds were later seen on Farewell Spit - and, as no possible staging areas exist south of Fiji, it shows that they made the long journey in one go, Schuckard says.

The route the birds choose to fly is also a surprise, he says.

"It was basically a direct line (on a map) from Alaska to Farewell Spit. We thought they might fly the weather patterns a bit."

The study is being funded and led by people monitoring birds for bird flu surveillance, the United States Geological Survey, the Point Reyes Bird Observatory Conservation Science in the US, and Massey University to learn more about the global migration of shorebirds in the Pacific basin. The birds touch down in Asia, and as such are potential carriers of the avian flu virus to Alaska.

On the New Zealand side, the Ornithological Society provides local knowledge and logistics to help make the programme successful.

Although Schuckard is sceptical about the potential of the non-domesticated waders to spread the virus, he says the study has provided crucial information about the migatory behaviour of the species.

Information on where the birds choose to feed in Golden Bay to prepare for their flight back to Alaska has also been useful.

"The Americans are interested in the big picture, but we are also interested in the local information that was completely unknown to us."

Four females and four males were caught in nets in Golden Bay. Data from their satellite transmitters shows that one bird left New Zealand on March 17 and was feeding in the staging area of the Yellow Sea six to seven days later. It stayed there for five to six weeks to put on the necessary fat for the second leg of its flight to Alaska, touching down there between May 7-9.

Schuckard says the study is exciting because it is a sharing of information on a global scale, which in some ways is unprecedented. He believes it is the way forward if conservation is to succeed.

Although Schuckard spends a lot of time monitoring birds, he says he still enjoys every bird count, and admits to having a soft spot for the bar-tailed godwit.

"That's evolution," he smiles, eyes shining. "Having a backyard that stretches from one side of the world to the other."

For more information, visit; http://www.prbo.org/cms/index.php

http://www.werc.usgs.gov/sattrack/shorebirds/overall.html

http://osnz.org.nz/

http://www.nzshorebirds.com/

- © Fairfax NZ News