Tytonidae

Taxobox
name = Barn-owls

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image_width = 270px
image_caption = Masked owl, "Tyto novaehollandiae"
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Strigiformes
familia = Tytonidae
familia_authority = Ridgway, 1914
subdivision_ranks = Genera
subdivision = "Tyto" "Phodilus" For fossil genera, see article.
synonyms =Tytoninae sensu Sibley & Ahlquist

Barn-owls (family Tytonidae) are one of the two families of owls, the other being the typical owls, Strigidae. They are medium to large sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. They also differ from Strigidae in structural details relating in particular to the sternum and feet.

The barn owls comprise two extant sub-families: the Tytoninae or "Tyto" owls (including the Common Barn Owl) and the Phodilinae or bay-owls. The Sibley-Ahlquist taxonomy unites the Caprimulgiformes with the owl order; here, the 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 barn owls are a wide ranging family, absent only from northern North America, Saharan Africa and large areas of Asia. They live in a wide range of habitats from deserts to forests, and from temperate latitudes to the tropics. The majority of the 16 living species of barn owls are poorly known. Some, like the Madagascar Red Owl, have barely been seen or studied since their discovery, in contrast to the Common Barn Owl, which is one of the best known owl species in the world. However, some sub-species of the Common Barn Owl possibly deserve to be a separate species, but are very poorly known.

Five species of barn-owl are threatened, and some island species have gone 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 Chickcharnie). The barn-owls are mostly nocturnal, and generally non-migratory, living in pairs or singly.

Description

The barn-owls' main characteristic is the heart-shaped facial disc, formed by stiff feathers which serve to amplify and locate the source of sounds when hunting. Further adaptations in the wing feathers eliminate sound caused by flying, aiding both the hearing of the owl listening for hidden prey and keeping the prey unaware of the owl. Barn-owls overall are darker on the back than the front, usually an orange-brown colour, the front being a paler version of the back or mottled, although there is considerable variation even amongst species. The bay-owls closely resemble the "Tyto" owls but have a divided facial disc, ear tufts, and tend to be smaller.

pecies

The fossil record of the 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 only known from the fossil record, the "Necrobyinae" and the "Selenornithinae". Numerous extinct species of "Tyto" have been described; see the genus page for more information.

Genus "Tyto"
* Greater Sooty-owl, "T. tenebricosa"
* Lesser Sooty-owl, "T. multipunctata"
* Australian Masked-owl, "T. novaehollandiae"
** Cave-nesting Masked Owl, "T. novaehollandiae troughtoni" - disputed; probably extinct (1960s)
* Golden Masked-owl, "T. aurantia"
* Lesser Masked-owl, "T. sororcula"
** Buru Masked-owl, "T. (sororcula) cayelii" - possibly extinct (mid-20th century?)
* Manus Masked-owl, "T. manusi"
* Taliabu Masked-owl, "T. nigrobrunnea"
* Minahassa Masked-owl, "T. inexspectata"
* Sulawesi Owl, "T. rosenbergii"
** Peleng Masked Owl, "T. rosenbergii pelengensis" - probably extinct (mid-20th century)
* Barn Owl, "T. alba"
** Eastern Barn Owl, "T. (alba) delicatula"
* Ashy-faced Owl, "T. glaucops"
* Madagascar Red Owl "T. soumagnei"
* African Grass-owl "T. capensis"
* Australasian Grass-owl "T. longimembris"

Genus "Phodilus"
* Oriental Bay-owl "P. badius"
** Samar Bay-owl "P. (badius) riverae" - probably extinct (mid-20th century)
* Congo Bay-owl, "P. prigoginei" - sometimes placed in "Tyto"

Fossil genera
* "Nocturnavis" (Late Eocene/Early Oligocene) - includes "Bubo" incertus"
* "Necrobyas" (Late Eocene/Early Oligocene - Late Miocene) - includes "Bubo" arvernensis" and "Paratyto"
* "Selenornis" (Late Eocene/Early Oligocene of Quercy, France) - includes "Asio" henrici"
* "Prosybris" (Late Eocene/Early Oligocene of Quercy? - Early Miocene of France)

Placement unresolved
* Tytonidae gen. et sp. indet. "TMT 164" (Middle Miocene of Grive-Saint-Alban, France) - "Prosybris"?

Placement of the Late Eocene/Early Oligocene genera "Palaeotyto" and "Palaeobyas" from Quercy (France) in this family is tentative; they might belong to the Sophiornithidae instead.

The supposed "giant barn-owl" "Basityto" from the Early Eocene of Grafenmühle (Germany) was actually a crowned crane ("Balearica");Fact|date=December 2007 the presumed "Easter Island Barn-owl", based on subfossil bones found on Rapa Nui, has turned out to be some procellarid (Steadman, 2006).

References

* Bruce, M. D. (1999): Family Tytonidae (Barn-owls). "In:" del Hoyo, J.; Elliott, A. & Sargatal, J. (eds): "Handbook of Birds of the World, Volume 5: Barn-owls to Hummingbirds": 34-75, plates 1-3. Lynx Edicions, Barcelona. ISBN 84-87334-25-3

* Steadman, David William (2006): "Extinction and Biogeography of Tropical Pacific Islands Birds". University of Chicago Press. ISBN 0-226-77142-3.

External links

* [http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=76 Barn-Owls] on the Internet Bird Collection