Editing Tytonidae (section)

===Predators and parasites===
[[File:Tyto alba -USA -three hissing and clicking-8.ogv|right|thumb|Three barn owl chicks threatening an intruder]]

[[Predator]]s of the barn owl include [[large American opossum]]s (''Didelphis''), the [[common raccoon]], and similar carnivorous [[mammal]]s, as well as [[eagle]]s, larger [[hawk]]s, and other owls. Among the latter, the [[great horned owl]] (''Bubo virginianus''), in the Americas, and the [[Eurasian eagle-owl]] (''B. bubo'') are noted predators of barn owls. Despite some sources claiming that there is little evidence of predation by great horned owls, one study from [[Washington (state)|Washington]] found that 10.9% of the local great horned owl's diet was made up of barn owls.<ref name=BNA>Marti, Carl D.; Poole, Alan F.; Bevier, L. R. (2005): "Barn Owl (''Tyto alba'')" ''The Birds of North America Online'' (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; [http://bna.birds.cornell.edu/bna/species/001 Barn owl]</ref><ref>{{cite journal|doi=10.2307/1368658 |jstor=1368658 |last1=Millsap |first1=Brian A. |last2=Millsap |first2=Patricia A. |title=Burrow Nesting by Common Barn-Owls in North Central Colorado |journal=The Condor |year=1987 |volume=89 |issue=3 |pages=668–670 }}</ref><ref name= Knight>{{cite journal | last1 = Knight | first1 = R. L. | last2 = Jackman | first2 = R. E. | year = 1984 | title = Food-niche relationships between Great Horned Owls and Common Barn-Owls in eastern Washington | journal = Auk | volume = 101 | pages = 175–179 | doi = 10.1093/auk/101.1.175 }}</ref> In Africa, the principal predators of barn owls are [[Verreaux's eagle-owl]]s (''Bubo lacteus'') and [[Cape eagle-owl]]s (''B. capensis'').<ref name= Steyn>Steyn, P. (1983). ''Birds of prey of southern Africa: Their identification and life histories''. Croom Helm, Beckenham (UK). 1983.</ref><ref name= Brown>{{cite journal | last1 = Brown | first1 = L. H. | year = 1965 | title = Observations on Verreaux's Eagle Owl Bubo lacteus (Temminck) in Kenya | journal = Journal of the East African Natural History Society | volume = 25 | pages = 101–107 }}</ref> In Europe, although less dangerous than the eagle-owls, the chief diurnal predators are the [[northern goshawk]] (''Accipiter gentilis'') and the [[common buzzard]] (''Buteo buteo''). About 12 other large diurnal raptors and owls have also been reported as predators of barn owls, ranging from the similar-sized [[Cooper's hawk]] (''Accipiter cooperii'') and scarcely larger [[tawny owl]] (''Strix aluco'') to huge [[bald eagle|bald]] (''Haliaeetus leucocephalus'') and [[golden eagle]]s (''Aquila chrysaetos'').<ref name= Voous>Voous, K.H. 1988. ''Owls of the Northern Hemisphere''. The MIT Press, 0262220350.</ref> As a result of improved conservation measures, the populations of the northern goshawk and eagle-owls are increasing, thus increasing the incidence of hunting on barn owls where the species coexist.<ref name=Martin>{{cite web |url=http://britishbirds.co.uk/article/the-daylight-activity-of-barn-owls/ |title=The daylight activity of barn owls |author=Martin, Jeff |date=2013-07-08 |work=BritishBirds |publisher=BritishBirds Rarities Committee |access-date=2014-07-19 |archive-date=2016-09-09 |archive-url=https://web.archive.org/web/20160909231900/http://britishbirds.co.uk/article/the-daylight-activity-of-barn-owls/ |url-status=dead }}</ref>

When disturbed at its roosting site, an angry barn owl lowers its head and sways it from side to side, or the head may be lowered and stretched forward and the wings outstretched and drooped while the bird emits hisses and makes snapping noises with its beak. Another defensive attitude involves lying flat on the ground or crouching with wings spread out.<ref name=Witherby1943>Witherby (1943) pp. 343–347</ref>

Barn owls are hosts to a wide range of parasites. Fleas are present at nesting sites, and externally the birds are attacked by [[Bird louse|feather lice]] and [[feather mite]]s, which chew the barbules of the feathers and which are transferred from bird to bird by direct contact. Blood-sucking flies, such as ''Ornithomyia avicularia'', are often present, moving about among the plumage. Internal parasites include the [[Trematoda|fluke]] ''Strigea strigis'', the [[tapeworm]] ''Paruternia candelabraria'', several species of parasitic round worm, and [[Acanthocephala|spiny-headed worms]] in the genus ''[[Centrorhynchidae|Centrorhynchus]]''. These gut parasites are acquired when the birds feed on infected prey.<ref name="BunnWarburton2010">{{cite book|author1=Bunn, D. S. |author2=Warburton, A. B. |author3=Wilson, R. D. S.|title=The Barn Owl|url=https://books.google.com/books?id=TF-zE_vOu9sC&pg=PA177 |year=2010 |publisher=Bloomsbury Publishing |isbn=978-1-4081-3961-5 |page=177}}</ref> There is some indication that female birds with more and larger spots have a greater resistance to external parasites. This is correlated with smaller [[bursa of Fabricius]], glands associated with antibody production, and a lower fecundity of the blood-sucking fly ''[[Carnus hemapterus]]'', which attacks nestlings.<ref>{{cite journal |author1=Roulin, Alexandre |author2=Riols, Christian |author3=Dijkstra, Cor |author4=Ducrest, Anne-Lyse |year=2001 |title=Female plumage spottiness signals parasite resistance in the barn owl (''Tyto alba'')  |journal=Behavioral Ecology |volume=12 |issue=1 |pages=103–110 |doi=10.1093/oxfordjournals.beheco.a000371|doi-access=free }}</ref>