page_title: Barred owl
section_title: Longevity and parasitism
hierarchical_section_title: Barred owl / Longevity and parasitism
caption_attribution_description: English: Why we need to dispose of fishing line responsibly. credit: Ken Sturm/USFWS
context_page_description: The barred owl, also known as the northern barred owl or, more informally, hoot owl, is a large species of owl. A member of the true owl family, Strigidae, they belong to the genus Strix, which is also the origin of the family’s name under Linnaean taxonomy. Barred owls are brown to gray overall, with dark striping on the underside contrasted immediately above that with similarly-dark and tight barring about their throat and nape. Barred owls are largely native to eastern North America, but have expanded their range to the west coast of North America where they are considered invasive. Mature forests are their preferred habitat, but they can also acclimate to various gradients of open woodlands. Their diet consists mainly of small mammals, but this species is an opportunistic predator and is known to prey upon other small vertebrates such as birds, reptiles, and amphibians, as well as a variety of invertebrates.
  Barred owls are brown to gray overall, with dark striping on the underside. Barred owls have typical nesting habits for a true owl, tending to raise a relatively small brood often in a tree hollow or snag in forested areas.
context_section_description: The barred owl is a naturally long-living bird. Some record lifespans recorded per banding studies in the wild are 18 years 2 months (initial banding Kentucky, died in Ohio) and 24 years and 1 month in Minnesota. There are several records of breeding barred owls nesting successfully for a decade or more. The record lifespan for a barred owl in captivity, where many animals can live longer without the stresses of surviving in wild conditions, was 34 years and 1 month, with six records of captive barred owls living over 30 years. Known causes of mortality are diverse, some due to predation (largely great horned owls, for nestlings to adults, and probably raccoons, for eggs, nestlings and fledglings). Some mortality is known to occur during hunting accidents. There are cases of barred owls being inadvertently killed in furbearer traps. Sometimes deaths occurs due to the defenses of prey. One barred owl was killed by the bite of an unknown rodent that was likely defending itself. Some cases of cannibalism between adult barred owls have been reported as well. This species, like other forest owls, is vulnerable to the respiratory disease aspergillosis. Spontaneous infections of West Nile fever are also known to kill wild barred owls. Barred owls were the most regularly infected with West Nile Virus of owl species in Georgia, as about 15% of studied barred tested positive (still at a lower rate than some hawks). Cases of Avipoxivirus are also known in barred owls but, as with West Nile virus, the rate of mortality to viral infection is not well-known. A case of follicular thyroid cancer was found in a wild barred owl that was unable to continue to fly. Fatty liver diseases have been recorded for barred owls in captivity. Eye lesions are fairly common in barred owls, but can be survived and possibly surgically corrected.
  Parasitism is frequent in barred owls as expected for many different kinds of wild birds. The parasite load was determined to be higher in larger owls in Florida like the barred and great horned owl and lower in smaller owl species, like eastern screech owl. While parasitic infestations are not typically detected as direct mortality causes, in some severe cases complications or direct death can occur. These cases of mortality are most widely recorded in cases of Toxoplasmosis, although generally owls have lower rates of this dangerous parasite than some other species of birds of prey. 26.7% of barred owls in one study had Toxoplasma gondii, the cause of Toxoplasmosis, upon necropsy study, with adults having it more often than immature birds. Lethal cases of Trichomoniasis are also known. The effect of other parasites are more poorly known beyond generally compromising their condition but in one case Sarcocystis may have caused paralysis in one barred owl. Other parasites recorded in barred owls include Eimeria varia, Novyella, Neodiplostomum as well as apparently rare species of Centrorhynchus and Tetrameres that were first found within barred owls. Trematode flatworms such as strigeids as well as Tylodelphys and Brachylaima are found in intermediate volume in barred owls relative to other owls. Invertebrates such as hippoboscid flies and Mallophaga are known to infect barred owls as ectoparasites but seldom at severe levels. Concern was expressed that barred owls may compromise spotted owl populations with novel parasites. However, studies of Haemoproteus in barred and spotted owls in northwestern California found that native parasites were finding a new host in barred owls and may have been transmitted from spotted to barred owls but that the barred owl acted as a poor parasite host and may have diluted the parasite levels in owl populations. Furthermore, there was no evidence found that barred owls were spreading parasites to spotted owls.
caption: A barred owl that drowned after entanglement with fishing line.
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