Of the genus Furnarius there are several species. The best-known is the
oven-bird of La Plata--the casara, or house-maker, of the Spaniards. It
builds its nest in an exposed situation, on the top of a vast bare rock
or cactus. It is composed of mud and bits of straw, and has strong,
thick walls--its shape being precisely that of an oven, or depressed
bee-hive. The opening is large and arched, and directly in front.
Within the nest there is a partition which reaches nearly to the roof,
thus forming a passage or ante-chamber to the true nest.