Introduction to the Black-billed Crested Tern: There is a mysterious bird species in the wetland of the Minjiang River Estuary. Its whereabouts are erratic, and humans know very little about it. This is an extremely endangered bird species, with less than 50 found worldwide. After mysteriously disappearing for 63 years, it magically reappeared. Scholars called it the "mythical bird". It is the Black-billed Crested Tern. Because it was first discovered in mainland China, it is also called the Chinese Crested Tern. Terns.