Nestlings are fed this regurgitated matter. Hoatzins forage in the early morning and early evening, and spend much of the time roosting quietly and digesting their meal. This feature has been compared to Archaeopteryx , the fossil proto-bird, and lend a antediluvian background to what is already a really weird bird. During breeding birds occupy densely packed exclusive territories, sometimes up to 28 nests in one tree. They are noisy and often vocalize in unison with a collection of hoarse cries, grunts, growls and hisses.
Hoatzins are limited to their lowland swamp habitat.
Thus in many riverine places in South America, Hoatzins will be found only in a few well-known places. The affinities and relationship of the Hoatzin have been the subject of much debate over the years. They have variously been grouped with the cranes, rails, tinamous, sandgrouse, doves, mousebirds or seriemas. Thus, whatever their relatives may be, they are unique and odd birds, and well deserving of the attention showered on them by visiting birdwatchers to South America. The flight shot of a hoatzin dashing across a small gap in the foliage was along the upper Rio Cristalino River, n.