A godwit in flight. Photo / Terry Oliver-Ward
A male kūaka/godwit is the talk of the global ornithological and bird-watching community after setting what appears to be a new world record for a non-stop migration marathon from Alaska to the Firth of Thames.
The godwit, fitted with a transmitter in New Zealand last November, was tracked non-stop across the Pacific Ocean, covering more than 12,000km in 9.3 days, touching speeds close to 100km/h.
The bar-tailed godwits, which weigh about 290g, spend much of their time in New Zealand. They are brown and grey, colours which blend well with the tidal mudflats where they feed.
They are waders with long legs and also have long bills, which they use to dig in the sand and mud for aquatic worms and molluscs.
The record-setting bird, named 4BBRW after the bands on its legs, was tracked by satellites. Its estimated flight time was 224 hours.
It left Alaska on September 18 and arrived in the Firth of Thames around 9.30pm on September 27 – nine straight days airborne. Unlike seabirds, there is no chance of picking up a bite to eat along the way.
The manager of the Pukorokoro-Miranda Shorebird Centre Keith Woodley, author of a book on the species, says the bird's astounding effort is being hailed as a record by bird watchers around the world.
"A bird named E7 did 11,680km back in 2007, and we think this bird has gone a bit further than that," Woodley said.
"He's truly a champion. This year, in particular, it's certainly something to lift the spirits of folks – even though we may get a bit envious of birds that don't have to do quarantine and negotiate border controls."
The godwits migrate from New Zealand to China in March and April. They stop over in the Yellow Sea to feed, before heading to Alaska in May and June, where they stay for several months during the northern hemisphere summer. They migrate back to New Zealand in September.
Woodley says tracking 4BBRW has given an important insight into how weather conditions in the Pacific can impact on the godwits' migration.
"We know wind is an important part of a migration strategy and, like a cyclist, they'll try to get a tail wind if they can – but they can't always manage it.
"This season there's been all sorts of odd weather patterns over the northern Pacific, which has affected how the birds have gone.
Recording the bird's journey has added crucial new information to wider understanding of the godwits' migration, Woodley says: "The little devices on the birds are solar-powered, and the people doing the research are expecting to get two, three maybe even four years of data if the devices keep working as they should.
"There's the possibility of following an individual bird over several migration cycles, and it would be very interesting to see if they follow the same route."
The godwits double their weight before their marathon migration, increase their red blood cells, and on their long flights they contract their digestive system - changes that occur three times a year.
They arrive at the Firth of Thames exhausted from their journey from Alaska.
"They seem to be able to recover very quickly, but we don't know quite how long that takes after a flight – they seem to have a very fast metabolism.
"Whether that recovery takes a matter of hours or days, we're still trying to work that out."
Technical advisor in the Department of Conservation, Bruce McKinlay, who represents DoC on the East Asian-Australasian Flyway Partnership (EAAFP) says the detail provided by the tracking is extremely important in identifying the paths migratory birds use. "Having this detail allows for much better discussions with the nations along the flyway to promote conservation of the species.
"The EAAFP is the key multi-lateral organisation working to promote the conservation of migratory waterbirds in the East Asian-Australasian Flyway.
"Tracking results such as this are the key building blocks for engaging with partners from as far away as Alaska and Siberia to protect habitats that are essential to completing these massive migrations."
Godwits are classified as declining because of a loss of habitat.
Although the length of the godwits' migration is impressive, it is not the longest in the bird world. That title is held by the tiny arctic tern, which has been tracked on a 71,000km zig-zag migration between Greenland and Antarctica.