On the outskirts of Foz there is a large area of ​​grass. There a group of Guira cuckoos had gathered to search for food. This bird caught a large spider, locally called a 'tarántula'. The Guira cuckoo is found in a wide range in eastern South America, from northern Brazil, Bolivia in the west, to northern Argentina in the south. The name comes from güirá which means 'bird' in Guaraní, the largest indigenous language in the area. The female is slightly larger than the male, and grows up to 34 cm (13 in) long. The call is whining and whistling. It is known for producing a foul-smelling odor... The bird is alone in its genus (Guira).