The Black-capped Donacobius (Donacobius atricapilla) is a conspicuous, vocal bird, found in in tropical swamps and wetlands in Central and South America.

The species has variously been considered a wren, thrush, or mockingbird. However genetic studies has shown it to be related to the Old World sylvioids, probably fairly closely related the grassbirds in the family Locustellidae. It is now placed in its own monotypic family (Donacobiidae).

Black-capped Donacobiuses are common in a wide range of Amazonian wetlands, including oxbow lakes, riparian zones, and other areas with tall dense aquatic or semi-aquatic vegetation. A third of the species range is outside the Amazon Basin, from Panama, northern Colombia, and western Venezuela, the Orinoco River system of Venezuela, to southeast coastal and inland Brazil, and neighboring countries southward, Paraguay, and extreme northern Argentina.

Mating for life, pairs of Black-capped Donacobiuses can be seen frequently and throughout the day atop thickets of dense lakeside or streamside vegetation. They often will engage in antiphonic dueting. Adult offspring will remain with their parents and help raise siblings from subsequent nesting periods in a system of cooperative breeding.