The horneros are members of the genus Furnarius in the family Furnariidae, native to South America. Horneros are brown birds with rather short tails and fairly long bills. They are known for building mud nests that resemble old wood-fired ovens (the Spanish word "hornero" comes from horno, meaning "oven"). These nests have a unique chambered construction. While many Furnariids have different nests, the hornero nest is the reason for the common name applied to the entire family; ovenbirds (though unrelated to the ovenbird, which is a parulid warbler). The size and exact shape of the hornero nest varies depending on the species. They generally lay two to four eggs, although the breeding behavior of the bay hornero is virtually unknown.