The Whistling Heron searches for food in open grasslands and shallow water. In Bolivia it is recorded from the lowlands to the southern Andean foothills.
It has a pink bill with a black tip and is about 45–50 cm long.
It forages alone or in pairs, walking through short dry grass or open shallow water while searching for food.
It builds loose stick platforms on high, thick branches, nesting alone or in small scattered colonies. The usual clutch is three or four eggs, with incubation lasting about 28 days.
The crown is black to slate with narrow nape plumes. The lores are pale blue to violet, the eyes pale yellow, and the back and wings blue-grey.
Immatures are duller, with streaked neck feathers, a greyer crown, and pale grey neck and chest. Yellow coloration is acquired after the feathers have grown.
An extinction-risk assessment has not been added yet.