The crest is a group of elongated feathers on the crown of a bird’s head. And depending on the species, the feathers may be raised or not at all. In the Malayan Night Heron (Gorsachius melanolophus), the black cap that is more or less white-spotted in the adult, projects down the nape as a drooping but erectile crest. But a black crest is absent in the juvenile.
The black crest of the Malayan Night Heron photographed by Dr Jonathan WK Cheah is just developing, indicating that the bird is a juvenile.
In the above-right image, the crest is erect, showing the blackish feathers with white spots. At the same time the coverts are ruffled.