The whistling heron is a medium-sized, often terrestrial heron of South America. It is the only species placed in the genus Syrigma. There are two subspecies, the southern S. s. sibilatrix and the northern S. s. fostersmithi.

The capped heron is a water bird endemic to the neotropics, inhabiting rainforest from the center of Panama to the south of Brazil. It is the only species of the genus Pilherodius, and one of the least known of the heron family, Ardeidae. It is superficially similar to the group of the night herons, but is active during daytime or at twilight.