The plains are covered by a formation similar to that of the Argentine pampas and by the alluvial deposits of the present rivers.
Extreme variations in temperature are often produced by cold south-west storms from the Argentine pampas, which sweep across southern Brazil as far north as Cape Frio, the fall in temperature sometimes being 22° to 27°.
The range of the sloth is from the Guianas south into Minas Geraes, the armadillo as far south as the Argentine pampas and the ant-eater from the Amazon south to Paraguay, though it is found in the Amazon region principally.
The shallow lagoons of the llanos, like those of the Argentine pampas, are favourite fishing grounds for these birds.
Though an expert climber, it is by no means confined to wooded districts, being frequently found in scrub and reeds along the banks of rivers, and even in the open pampas and prairies.