There are 35 sub-species of Barn Owl. Barn Owls do not build nests themselves, but rely on a variety of nesting sites for laying their eggs. Tree cavities, rock ledges, chimneys & ledges in barns are among the sites that may be used & Barn Owls have sometimes been known to make their own burrows in riverbanks.
Organisms in biology are classified by this system: kingdom, phylum, class, order, genus, species. Kingdoms being the largest groups. Species is the smallest major group before they divide into sub groups. So Genus would be the next group larger if that is what you mean, but all the other groups would be larger as well.
The hierarchy of biological classification's eight major taxonomic ranks. A domain contains one or more kingdoms. Intermediate minor rankings are not shown. In biology, kingdom (Latin: regnum, plural regna) is the third highest taxonomic rank, just below domain. Kingdoms are divided into smaller groups called phyla.