The Pacific Reef Heron (Egretta sacra) also known as the Pacific Reef Egret is a bird of the heron family that is resident from South-east Asia region to Australia and New Zealand.
It is a peculiar heron species that exhibit non-sexual dimorphism, that is that some birds are entirely white-plumaged (white-morph) and some entirely charcoal grey (dark morph). The grey plumaged birds formed the majority of the population worldwide (but apparently the opposite in Singapore in the past) but they breed freely. There have also been cases of intermediate coloured morph but that is rarer.
These herons are predominantly coastal birds, and can be found near the shore, where they time their feeding according to the tide level. They hunt for fish, crustaceans and molluscs om the shallower part of the water.
In Singapore, they can be found near the seaside, with the largest population at the shores of the various southern islands. However they can be found in other places. These past few years, they have been reported near West Coast Park, Pasir Ris Park, Seletar Dam, Pulau Ubin and even a canal along Telok Kurau.