As fears of a global bird-flu pandemic grow, many people are wondering whether the Mai Po Nature Reserve should be closed to prevent migratory birds from spreading the deadly disease to visitors.
Why is Mai Po so attractive to these birds? The wetlands play an important role in their long journey.
Every year, an estimated two to three million birds migrate from their summer breeding grounds in Siberia and northeastern China to their winter havens stretching as far south as Australia.
Along their migration route, these waterbirds have to rely on a number of staging posts where they can rest and feed (refuel). They cannot fly non-stop on their annual journey which may involve a round trip of 33,000 kilometres.
The wetlands in and around Mai Po and Inner Deep Bay are important stops for them.
Each winter, tens of thousands of waterbirds arrive from their northern breeding grounds to spend winter around the Deep Bay wetlands.
This includes 25 per cent of the world population of the endangered Black-faced Spoonbill, and significant numbers of equally rare species, such as the Saunders' Gull and Dalmatian Pelican.