New research led by the University of Auckland has used ancient DNA to reveal the incredible distances that some birds flew to reach their current homes.
The study, which was undertaken in collaboration with an international team of researchers, looked at the genetic diversity of the New Zealand mallard duck (Anas platyrhynchos novaeseelandiae) and found that it had originated from a single source population in East Asia.
The researchers used archaeological remains to date the mallard's arrival in New Zealand to between 1500 and 800 years ago, during a period known as the 'Great Polynesian Migration'.
The mallard's ancestors would have had to fly at least 4,500 kilometres across the Pacific Ocean from their original homeland in order to reach New Zealand, showcasing an impressive feat of endurance and navigation.
The study's lead author, Dr Jessica Metcalf from the University of Auckland's School of Biological Sciences, says the research highlights the extraordinary journeys undertaken by birds in order to reach their current habitats.
"It is incredible to think about these birds flying thousands of kilometres across the open ocean, relying on their instincts and internal compass to find their way," she says.
The researchers also found that the mallard's genetic diversity began to decline after it arrived in New Zealand. This is likely due to the limited number of mallards that would have initially reached New Zealand, as well as the limited genetic diversity within the source population.
"This decline in genetic diversity is a concern because it can lead to an increased susceptibility to disease and reduced reproductive success," says Metcalf.
"The mallard is just one example of how the ancestors of many bird species undertook epic journeys to reach New Zealand. It underscores the importance of protecting our unique bird species and their habitats so they can continue to flourish in their current homes."
