The Greater Crested Tern is a large, distinctive seabird known for its shaggy black crest, long yellow bill, grey back, white belly, and black legs, often seen along tropical/subtropical coasts worldwide.

Although considered as a breeding resident of Malaysia, most likely to be at Pulau Layang Layang, Sabah only for Malaysian territories. At Teluk Air Tawar – Kuala Muda IBA they can be seen perching on those mussels post just off the coast, but at coastal areas without this convenient perch, they will rest on sandbars and mudflats.

https://datazone.birdlife.org/species/factsheet/greater-crested-tern-thalasseus-bergii