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The birds, according to the scientists, headed south over the Aleutian Islands and then onto the Pacific Ocean, passing over Hawaii and Fiji. Scientists believe strong easterly winds along the way prolonged the birds’ journey and pushed them towards Australia.
“They are flying over open ocean for days and days in the mid-Pacific; there is no land at all. Then they get to New Caledonia and Papua New Guinea where there are quite a few islands and, we might be anthropomorphising, but it really looks like they start spotting land and sort of think: ‘Oh, I need to start veering or I will miss New Zealand’,” Conklin told the Guardian.
The satellite recorded a point-to-point flight of 12,854 kilometres, but scientists have estimated that the distance travelled will have been around 12,200 kilometres once rounding errors are accounted for. The previous longest non-stop flight on record was by a bird that flew 11,680 kilometres. That effort was recorded in 2007, and it was also by a bar-tailed godwit (on that occasion female).
While the male bird, which weighs between 190 grams and 400 grams, can double in size before a long flight, scientists say it’s also able to shrink its internal organs to lessen the carried load.
Scientists believe, but have not yet proven, that the birds do not sleep on their journey, despite flapping their wings non-stop. “They have an incredibly efficient fuel-to-energy rate,” Conklin said.
“There are other birds that make similar-scale flights of say 10,000 (kilometres) but there are not a whole load of places in the world where it is necessary,” Conklin said. “So it is not necessarily that this is the only bird capable of it – but it is the only bird that needs to do it.”
The route along the Pacific functions as an ‘ecological corridor,’ scientists suggest, mostly because it is relatively free of disease and predators. However, climate change could soon render it an unsuitable route, as the frequencies and strengths of the winds along the passage change.
