Soon it will head back north to the demilitarised zone between North and South Korea where it can breed undisturbed

I opened the windows to the hide and was greeted by a mass of birds. Hundreds of cormorants, gulls, herons, egrets, ducks and waders, all feeding frantically as the rising tide covered up the fertile mud. Overhead, black kites patrolled half-heartedly, occasionally provoking the other birds to take to the wing in short-lived panic, before settling back down to feed or rest.

I witnessed this spectacle at the World Wide Fund for Nature’s Mai Po nature reserve in Hong Kong, justly celebrated as one of the most important wetlands in the world. Either side of high tide, birds gather here in vast numbers against the backdrop of Shenzhen, one of the fastest-growing cities in the world, just across the border in mainland China.