Flight of the godwit
Bar-tailed godwits can fly about 12,000 km at one time – further than any other known bird. This recent discovery excited ornithologists around the world. Dr Phil Battley from Massey University’s Ecology Group and PhD student Jesse Conklin (now Dr), have been tracking and researching godwits’ flights from New Zealand.
Flight path of E7
The godwit E7 was tracked by satellite (feedback is shown by yellow dots) from New Zealand to China and then to Alaska. She then flew non-stop back to New Zealand.
The flight path
The researchers found that godwits leave New Zealand from various estuaries (Manawatū, Miranda, Golden Bay, Christchurch, Otago and Southland) from the second week of March to the end of the month. It seems they fly direct from New Zealand to eastern Asian estuaries (Japan, Korea and China). The birds leave Asia for breeding grounds in Alaska in May. After breeding, they refuel on the coastlands of south-western Alaska (Yukon-Kuskokwim delta and Alaska Peninsula). They then return to New Zealand on a non-stop flight across the Pacific Ocean, taking 7–9 days, from September to mid-October.
Preparing for flight
To prepare for the flight, the godwits need fuel. The average godwit normally weighs about 300 grams. After fuelling for the trip, they weigh about 600 grams – doubling their weight in fat. Even their kidneys, liver and intestines shrink to make room for more fat (so they don’t exceed maximum weight for efficient flight). Their fuel (food) is predominantly marine polychaete worms, which they extract from muddy sediments using their long bills. They also eat small bivalves and crabs.
Getting ready to go
PhD student Jesse Conklin, from Massey University, explains how you can tell when godwits are getting ready to migrate. He talks about their preflight behaviour, and you can hear the calls they make as they round each other up to go.
While in New Zealand, birds also replace their flight feathers, growing new ones so that they will be strong enough to last them 30,000 km flight.
You can tell if godwits are getting ready to take off on migration. They become more active than usual, walking around, fluffing their feathers, having a bath and calling to others with a very distinctive call – it’s as if they’re asking the others who else is coming on this trip. They leave in groups.
The flight
Godwits fly extraordinary distances yet they aren’t particularly different from other migrating birds. It’s just that they do everything really well. Structurally, they have a wing shape designed for fast, efficient long-distance flight. Their feathers are very sleek so that the wind can pass over as smoothly as possible.
Godwits in flight
Massey University’s Dr Phil Battley describes godwits in flight including flapping ability, speed, flying altitudes, streamlining, time taken for non-stop flight and V-formation flight
Point of interest: In this clip, you’ll see a flock of birds flying in V-formation. These are Canadian geese, who, like godwits, use the V-formation.
The birds also counteract wind resistance (drag) by flying in flocks. The benefit of flying in a flock is that they fly in a V-formation. This means the bird at the front cuts into the wind first so that there is less wind resistance for the other birds. This makes flying easier for them, and as a result, the whole flock benefits by not becoming so exhausted. The birds have turns at taking the lead because the lead bird encounters the most drag and has to work the hardest.
Godwits fly at about 60 km/h, flapping their wings most of the way. They do not have completely waterproof feathers, so they can’t stop for a rest at sea. During the flight, they use up the fat they have stored plus some of their muscle tissue, which increases before the flight to cope with their extra weight. As they get lighter, the muscles do not need to work as hard and therefore don’t need to be as big.
How do they do it?
Dr Phil Battley, from Massey University, describes what godwits have and do to be able to make the long flight.
Migration timing
In his PhD research, Jesse explored the relationship between when godwits leave New Zealand and when they return. It appears groups of godwits return to New Zealand in the same order as when they left.
Jesse discovered that migration timing is linked to the breeding grounds in Alaska. The birds seem to know exactly when to leave, and they leave at much the same time every year.
Migration timing
Jesse Conklin explains an exciting research finding that came from using geolocators – the time birds leave for migration from New Zealand is directly linked to breeding grounds in Alaska. Birds breeding in northern regions leave New Zealand later – giving time for the area to thaw so that it is suitable for breeding. Jesse’s research is part of his work as a PhD student at Massey University.
Alaska is frozen over for about 6 months of the year. As it thaws out, millions of birds come from all over the world to breed. Each latitude throughout Alaska starts summer at a different time. The southern parts thaw first followed by the more northern parts. It appears godwits always go to the same breeding grounds.
The godwits that leave New Zealand in early March breed in the south, where the ice melts first, and birds that leave at the end of March breed in the north, where the ice melts last.
Nature of science
Sometimes it’s hard to get funding for science projects that don’t seem to have a benefit for people. Funding that enabled the discovery of godwits’ flight distances was initially granted because of a concern that godwits may spread bird flu around the world. Without this link to a benefit for people, the research may never have happened.
Related content
Dr Phil Battley and Dr Jesse Conklin are two scientists who study and track godwits.
Activity idea
In this activity , students explore the incredible flight of a special bird known as E7 to learn about the migratory flight of bar-tailed godwits from New Zealand.
Useful links
In Your flight itinerary has changed Dr Jesse Conklin shares his 14-year journey studying Bar-tailed Godwits.
Alison Ballance joins a team catching and tagging 45 godwits to find out the sleep secrets of the kuaka, find out more in this RadioNZ Our Changing World programme from March 2024.
Watch this fascinating documentary from the TVNZ Sunday programme, which followed a team from Pūkorokoro Miranda Naturalists’ Trust on their visit to DPRK – North Korea to count godwits in April 2018.
Visit the website of the Pūkorokoro Miranda Shorebird Centre .
