Quote: The tufted gene is lethal in homozygous dose. Sometimes even when heterozygous. If the araucana has tufts, than a lethal gene may have been passed to the offspring, even though the leghorn did not provide a copy. Rumplessness has nothing to do with it, although rumplessness can make fertility an issue. For both these reasons, araucana breeders typically use both non-tufted and tailed birds in their breeding programs. You just don't (usually) see them in the show hall.