Crested terns (Sterna bergii) may spend lots of time grooming, but it only takes a small gust of wind to ruffle the long head feathers and they look ... well ... scruffy. These individuals at Sandy Point, Williamstown, were constantly engaged in trying to appear at their best, while the silver gulls stood around being flawless. (Perhaps they hang around with crested terns to boost their own self-esteem?)
Crested terns occur in coastal areas (and sometimes on large rivers) all around the Australian coast. They are also found throughout Indonesia, the Philippines, southern Africa and islands of the western Pacific and western Indian oceans.
A study of the diet of chicks in a Phillip Island colony showed that Australian anchovies (Engraulis australis) and jack mackerel (Trachurus declivis) were the most popular items on the menu. Anchovies also made up the main part of the diet of little penguins (Eudyptula minor). (Hold the pizza.) So when the anchovy population declines, so do those of the terns and penguins. Add to that the commercial fish catch. In bad years that's a lot of competition for a limited resource.
Chiaradia, A., Dann, P., Jessop, R. and Collins, P. (2002). The diet of Crested Tern (Sterna bergii) chicks on Phillip Island, Victoria, Australia. Emu 102 (4): 367–371.