Félix de Azara was a Spanish military officer and amateur naturalist who was sent to the Río de la Plata to negotiate a border dispute with Brazil. In 1777, a treaty was agreed between Spain and Portugal that required both nations to send a delegation to South America to define the boundary between their colonies. Azara arrived in the region in 1781 but the Portuguese delegation never arrived. Remaining in the area until 1801, Azara instead decided to prepare an accurate map of the region and to study its natural history. While in South America, Azara managed to identify many new species of birds and animals, 221 of which now serve as type specimens.

He sent reports of his discoveries back to his brother, who was serving as the Spanish Ambassador to France in Paris, for publication. On his return to Europe, he joined his brother in the French capital and published this account of his travels. The account provides much information about the geography and wildlife of Argentina, Uruguay and Paraguay. Azara was also a critic of the noted French naturalist George-Louis Leclerc, comte de Buffon and used his works to correct errors that he believed Buffon had made in his extensive Histoire Naturelle.