He also contributes to the research of these animals by doing bird ringing, which refers to the attachment of tags to the legs or wings of birds so that they can easily be identified.

"Bird ringing helps researchers to keep track of the movements of the birds and their life history. It is common to take measurements and check the condition of their feathers, age and sex during ringing," said He.

One of the birds He tagged when he was pursuing his PhD in 2012 was a black-faced spoonbill, one of the rarest and most endangered species in the world.

"Two years later, I saw the bird again in a village in Nantong, Jiangsu province and I felt this sense of achievement. It was like coming across an old friend," he quipped.

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