Miracle of endurance
- 5 days ago
- 3 min read
Updated: 4 days ago
It is a sure sign that autumn is here and winter is coming when the Eastern bar-tailed godwits, or kuaka, leave Ōhiwa Harbour. Weeks before they are off to their breeding grounds in Alaska, it is beautiful to watch the flocks of hundreds rising up and down in perfect harmony over the harbour.
Their phenomenal, long-distance, non-stop flight from Alaska to New Zealand has attracted the curiosity of scientists and bird enthusiasts for many years. The Pūkorokoro Miranda Shorebird Centre near Thames has been tracking some of the kuaka for some time, gaining valuable insights into the super bird’s life. ‘E7’ was the female godwit fitted with an implanted transmitter in 2007 who first confirmed that kuaka make the flight from Alaska to New Zealand non-stop. She completed this 11,680 km flight in 8 days and 4 hours doing an average of 60km/h. This is still the record today. In terms of the longest non-stop flight recorded, the current record holder is ‘4BBRW’ who flew at least 13,050 km non-stop from Alaska to Australia. Of course, what these two birds did were just two examples of what thousands of godwits do each year as they travel between breeding and non-breeding grounds.
What makes these birds go on this massive flight? And why do they not stop for a rest at sea or on an island? Godwits are waders and, unlike other seabirds, not equipped to rest on the sea. They lack the webbed feet and more oily plumage of these water birds. Their main feeding habitats are the arctic tundra and tidal mudflats. There may be some mudflats in the small islands and coastal areas along their migration path, but there won’t be enough food in these areas to support the hundreds of thousands of migratory waders that are a part of this East Asian-Australasian Flyway. Yet, they will stop if they are forced too, due to weather perhaps, but this is the exception. Also, on their return journey to their breeding grounds in Alaska, they are known to refuel at the shores of the Yellow Sea in East Asia. Plus, godwits are often in a hurry. Juveniles will need to leave before the northern winter sets in and the food sources disappear. When these juveniles arrive in New Zealand, they are only about 12 weeks old!
According to Emeritus Professor Michael Walker (Whakatōhea), son of Dr Ranginui Walker, ‘the kuaka has a magnetic sense for long distance navigation. When they are flying at night they can’t see, so just like Cook and Tupaia they must be able to determine a position’. Experts believe that while airborne, godwits sleep with one eye open, switching off half their brains at a time, navigating by the stars and the Earth’s magnetic field.
However, conditions on the godwits’ and other shorebirds’ flyway have become increasingly challenging as mudflats are being reclaimed and developed for human economic gain. The wetlands south of Donggang in China are a critical stopover as kuaka travel from New Zealand to Alaska. It is an area under high development pressure. The Pūkorokoro Miranda Shorebird Centre has worked together with Chinese environmentalists for many years to ensure the Yalu Jiang Estuary Wetland National Nature Reserve is not further compromised by the reclamation of vital mudflats. Ten years ago, in March 2016, the Department of Conservation (DOC) and the State Forestry Administration (SFA) of China signed a Memorandum of Arrangement (MOA) that enables the two countries to work together to protect wetlands used by godwits, red knots and other migratory shorebirds during their annual migrations.
Generally, godwits live between 10 to 15 years which gives them quite a number of return trips to Ōhiwa Harbour. Because once they have come here, they come again. However, not all godwits go back to Alaska. At least a couple of hundred stayed at the harbour last winter. Thanks to those deciding to stay this year, summer at Ōhiwa gets a bit of an extension.
More interesting facts about the bar-tailed godwits or kuaka, including on the science behind the tracked birds intriguing names, are available on the Pūkorokoro Miranda Shorebird Centre’s website.
Sources:
The high-risk life of the bar-tailed godwit: endurance flyers under threat from development. Guardian, 28 September 2023
Supporting shorebirds’ 24,000km flight, Beehive, 19 March 2016
