Most subspecies for an owl species

The species of owl split into the most subspecies is the common barn owl Tyto alba, which is generally split into at least 27 separate subspecies (some authorities recognise even more). The reason for its splitting into such a sizeable number of subspecies is its enormous distribution, occurring over a greater area of the globe than any other owl species, leading to subspeciation taking place throughout its range. In recent times, some authorities have split off the New World barn owls from the remainder as separate species, as well as elevating several Old World subspecies to the level of species, but these taxonomic measures have not as yet been widely accepted.

Habitat greatly influences the outward, physical appearance of the barn owl's numerous subspecies. Island subspecies are generally smaller than mainland ones; and for effective camouflage purposes, protecting them from predators and concealing them from prey, forest-dwelling subspecies are generally much darker in colour (and shorter-winged, too) than those that inhabit more open, grassy localities.