Onon’s Epic Journey

Onon returned after a 26,000km round trip that took in 27 border crossings and 16 countries. Photograph: Mongolia Cuckoo Project/Birding Beijing

Thanks to ornithologists like Dr Hewson, and to scientific instruments like the tracking device on Onon, we can see that Onon the cuckoo has made one of the longest migrations recorded by any land bird:

Guardian graphic. Source: The Mongolia Cuckoo Project

Cloud cuckoo land? How one bird’s epic migration stunned scientists

When Onon the common cuckoo took off from Mongolia last June no one expected him to make a 26,000km round trip to southern Africa

Onon moments before he was released on 8 June 2019. Photograph: Mongolia Cuckoo project/Birding Beijing

When Onon took off above the rolling hills of the Khurkh valley in Mongolia last June, researchers had no idea if they would see him alive again. Along with one oriental cuckoo and three other common cuckoos, each fitted with a tiny tracking device, he was about to embark on an epic journey to southern Africa.

Last month, he was the only bird to return safely with his tracker intact.

“It’s an amazingly long migration,” says Dr Chris Hewson, senior research ecologist at the British Trust for Ornithology, who said Onon’s 26,000km round trip was one of the longest journeys recorded by any land bird.

Onon has not only amazed conservationists, but gripped social media across the globe. As coronavirus lockdowns brought the world to a virtual standstill, fans followed online updates from the Mongolia Cuckoo Project, watching in awe as Onon cruised across oceans and made 27 border crossings in 16 countries.

He returned on 27 May, having become a media celebrity in India, Kenya and Sweden. Back in Mongolia, he appeared on television and made newspaper headlines.

Researchers are now studying data from his journey for clues about why cuckoos travel as far as they do, and how they might be affected by the climate crisis.

Hewson, who worked on the project with the Wildlife Science and Conservation Center of Mongolia, admits he did not believe cuckoos were such proficient migrators. “Although they’ve got nice long wings, when they’re flying around the breeding site they look slightly ungainly compared to the other birds,” he says. In fact, cuckoos such as Onon, which migrate in search of caterpillars, their favourite food, travel remarkably fast, he adds. Using tailwinds, they can motor for more than 1,000km a day for a week…