Breeding season: The breeding season is very extended and variable. Generally, this is April-September in the north, September-January in Brazil, and January in Uruguay (Kushlan and Hancock 2005).
Nests: Whistling Herons build loose platform nests singularly or in small, scattered colonies in mature trees. These nests are generally on a thick horizontal branch high in the tree, anywhere from 3 to 11 m above the ground. They often return to previous locations from one year to the next (Kushlan and Hancock 2005).
Eggs and clutch: A normal clutch is 3-4 pale blue and speckled eggs, measuring 46 – 48 x 35–37mm. The incubation period is aproximately 28 days. After hatching, the young beg by hissing and drooping their wings. Often only two young survive to fledging (Sick 1993, Kushlan and Hancock 2005).