Spanish sparrow
The taxonomic status of the Italian sparrow has been a matter of debate. It has been variously regarded as a stable hybrid between the house sparrow and Spanish sparrow, or as a subspecies of either the house or Spanish sparrow. Many authorities, including the "Handbook of the Birds of the World", recognise it as a separate species, if only for convenience. Others, including many conservation groups, consider the Italian sparrow a simple hybrid and ignore it. The chromosomes of Italian sparrows are distinct from those of the house sparrow, but mitochondrial DNA suggest a close relation to the house sparrow.