The bird family Tytonidae, which includes the barn owls Tyto and the bay owls Phodilus, is one of the two families of owls, the other being the true owls or typical owls, Strigidae. Tytonidae are medium to large owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. Tytonidae also differ from the Strigidae in structural details relating in particular to the sternum and feet. The family is wide-ranging, although they are not very tolerant of severe winter cold, so are absent from northern areas of Europe, Asia, and North America; they are also absent from driest desert regions. They live in a wide range of habitats from semi-deserts to forests, and from temperate latitudes to the tropics. Within these habitats, they live near agricultural areas with high amounts of human activity. The majority of the 20 living species of barn owls are poorly known. Some, like the red owl, have barely been seen or studied since their discovery, in contrast to the western barn owl Tyto alba, which is one of the best-known owl species in the world. However, some subspecies of the western barn owl possibly deserve to be separate species, but are very poorly known. Five species of barn owl are threatened, and some island species went extinct during the Holocene or earlier (e.g., Tyto pollens, known from the fossil record of Andros Island in the Bahamas, and possibly the basis for the mythical chickcharney). Barn owls are mostly nocturnal and generally non-migratory, living in pairs or singly.
Taxonomy and systematics
Barn owls consist of two extant subfamilies: the Tytoninae or Tyto owls (including the western barn owl) and the Phodilinae or bay owls. The modern genera Tyto and Phodilus are thought to have originated from a common ancestor from the Oligocene period. It is believed the modern genus Tyto descended from large nocturnal birds in the West Indies during the Quaternary. The systematics of this group began with the discovery of Tyto ostologa (now extinct), whose remains were found in north-central Haiti. This discovery led to the finding of Tyto pollens, Tyto noeli, and Tyto riveroi in nearby cave deposits, all of which are now extinct and were also considered giant. The Sibley-Ahlquist taxonomy unites the Caprimulgiformes with the owl order; here, barn owls are a subfamily, Tytoninae. This is unsupported by more recent research (see Cypselomorphae), but the relationships of the owls in general are still unresolved. The ashy-faced owl (T. glaucops) was for some time included in T. alba. Based on DNA evidence, König, Weick & Becking (2009) recognised the American barn owl (Tyto furcata) and the Curaçao barn owl (T. bargei) as separate species. They proposed that T. a. delicatula should be split off as a separate species, to be known as the eastern barn owl, which would include the subspecies T. d. delicatula, T. d. sumbaensis, T. d. meeki, T. d. crassirostris, and T. d. interposita. As of 2021, the International Ornithological Committee had not accepted the split of Tyto delicatula from T. javanica. Some island subspecies are occasionally treated as distinct species, a move which should await further research into barn owl phylogeography. According to Murray Bruce in Handbook of Birds of the World Volume 5: Barn-owls to Hummingbirds, "a review of the whole group [is] long overdue". Molecular analysis of mitochondrial DNA shows a separation of the species into two clades, an Old World alba and a New World furcata, but this study did not include T. a. delicatula, which the authors seem to have accepted as a separate species. Extensive genetic variation was found between the Indonesian T. a. stertens and other members of the alba clade, leading to the separation of stertens into Tyto javanica. Twenty to thirty subspecies are usually recognized, varying mainly in body proportions, size, and colour. Barn owls range in colour from the almost beige-and-white nominate subspecies alba, erlangeri, and niveicauda, to the nearly black-and-brown contempta. Island forms are mostly smaller than mainland ones, and those inhabiting forests have darker plumage and shorter wings than those living in open grasslands. Several subspecies are generally considered to be intergrades between more distinct populations.
Extant genera Two extant genera are accepted:
Genus Tyto – barn owls, grass owls and masked owls (18 species) Genus Phodilus – bay owls (2 species)
Genus Tyto
Some of the Tyto species that exist include the western barn owl (Tyto alba), the American barn owl (Tyto furctata), and the eastern barn owl (T. javanica, including the Australian barn owl T. javanica delicatula). Within each of these species, there are many subspecies. Of the western barn owl there are 10 subspecies: T. a. alba, T. a. detorta, T. a. erlangeri, T. a. ernesti, T. a. gracilirostris, T. a. guttata, T. a. hypermetra, T. a. poensis, T. a. schmitzi, T. a. thomensis. Of the American barn owl, there are 10 subspecies: T. f. bargei, T. f. bondi, T. f. contempta, T. f. furcata, T. f. guatemalae, T. f. hellmayri, T. f. niveicauda, T. f. pratincola, T. f. punctatissima, T. f. tuidara. Of the Australian barn owl, there are 7 subspecies: T. j. crassirostris, T. j. delicatula, T. j. javanica, T. j. interposita, T. j. meeki, T. j. stertens, T. j. sumbaensis. The western barn owl (T. alba) can be found in Africa and parts of Asia, including Eurasia. The American barn owl (T. furcata) can be found from North to South America. Lastly, the Australian barn owl (T. delicatula) can be found in Australia, New Zealand, Polynesia, and Asia.
Genus Phodilus This genus includes the Oriental bay owl (P. badius) and the Sri Lanka bay owl (P. assimilis). The genus has a much smaller distribution than Tyto, with Oriental bay owls found in tropical Asia and Sri Lanka bay owls found in Sri Lanka and southwestern India.
Extinct genera The fossil record of barn owls goes back to the Eocene, with the family eventually losing ground to the true owls after the radiation of rodents and owls during the Neogene epoch. Two subfamilies are known only from the fossil record: the Necrobyinae and the Selenornithinae. At least four extinct genera of barn owls have been described:
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