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BC Conservation Data Centre: Species Summary


Tyto alba
Barn Owl


 
Scientific Name: Tyto alba (Scopoli, 1769)
English Name: Barn Owl
 
Classification / Taxonomy
Scientific Name - Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: B-BNOW
Kingdom Phylum Class Order Family
Animalia Craniata Aves Strigiformes Tytonidae
   
Conservation Status / Legal Designation
Global Status: G5 (Apr 2016)
Provincial Status: S2? (Mar 2015)
BC List: Red
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Threatened (Nov 2010)
SARA Schedule: 1  -  Threatened (Jun 2018)
General Status Canada: 3 - Sensitive (2005)
Migratory Bird Convention Act:
   
Ecology & Life History
General Description: ADULTS: body length 30-37 cm, wingspread 104-120 cm (Colvin 1984, Marti 1990). Upper plumage golden-brown with varying amounts of gray. Breast and belly color ranges from white to buff and is sparsely to heavily speckled with small black spots. Head lacks ear tufts and has relatively small dark eyes and a distinctive heart-shaped facial disk which ranges in color from white to buff.

Sexes differ in size and plumage. Females are larger and heavier (569 g vs. 475 g), darker, and more heavily speckled than males (Bloom 1978, Colvin 1984). Variability of these characteristics makes it difficult to objectively determine the sex of some individuals. Linear discriminant functions which use weight and color measurements can be used for determining sex (Colvin 1984).

JUVENILES: resemble adults. Males younger than one year may have buff coloration on the breast (whereas adult males almost always lack such coloration) but are not as heavily speckled as females (Bloom 1978). Molt patterns provide a means of distinguishing adults from juveniles and for accurately aging individuals through 36 months (Bloom 1978).

VOCALIZATIONS: Fifteen vocal and two nonvocal sounds were described by Bunn et al. (1982). B. Colvin (pers. comm.) described the five most frequently heard vocalizations: 1) the "contact call" is a drawn-out screech frequently given in flight when approaching a nest site from a distance; 2) the "alarm call" is an intense screech made in response to human or other disturbance which is typically given at a nest site and only after chicks have hatched; 3) "squeaking/ticking calls" are rapid, high-pitched notes which are associated with pair bond maintenance or distress situations; these calls are commonly produced during courtship, incubation, and first evening flights after chicks have hatched; 4) "snoring" is a greatly varying hiss which is repeated persistently by juveniles in and out of the nest; this call is used for food begging and may be heard at nest sites from sunset to sunrise; and 5) the "defensive hiss" is a very loud and prolonged hiss typically produced by nestlings when disturbed.
Subspecies Comments: Tyto alba pratincola. There is only one subspecies recognized in N. America.
Identification Comments: Medium-sized owl (32-40cm). White, heart-shaped face ringed with tan, dark eyes and light bill; no ear tuffs. Breast and underparts white or mostly white to tawny. Breast and underparts of some females are slightly darker and more heavily spotted with black than male. Head, wings and back are tawny buff colour, finely marked with black and white spots. Noticeably long sparsely feathered legs, tarsi light grey with dark grey claws. Wings long and rounded. Tail short.
Global Reproduction Comments: Nests in late winter, spring, and/or early summer in most of North America. Breeds throughout year in Texas. Nests with eggs or young have been found in the northeastern U.S. during every month of the year (Poole 1930; Bent 1938; Scott 1950; Stewart 1952; C. Rosenburg, unpubl. data), but peak egg laying occurs during mid-April (Colvin 1984, Byrd and Rosenburg 1986). Second clutches are typically laid between June and September (Wallace 1948, Keith 1964, Reese 1972, Soucy 1979). As many three broods per year; some California birds attempt two broods per year; one brood per year in most of the range. Clutch size ranges between one to 13 eggs (Bent 1938, Parker and Castrale 1990) with the mean clutch size ranging between four to six eggs (Otteni et al. 1972, Reese 1972, Smith et al. 1974). Clutch size depends on condition; increases with food supply and after mild winters in some areas. Eggs are usually laid two days apart and hatch asynchronously since incubation starts after the laying of the first egg (Wallace 1948, Smith et al. 1974). Incubation by female, 21-24 days for single egg, 29-34 days for full clutch (Smith et al. 1974, Marshall et al. 1986). The peak of hatching in the Northeast occurs in mid-May (Colvin 1984; Byrd and Rosenburg 1986; S. Smith, pers. comm.). Female broods and feeds young, male brings food. Young reportedly fly at 50-55 days in England; young fledge at 8-10 weeks in U.S. (Pickwell 1948, Reese 1972, Smith et al. 1974). Peak fledging occurs in mid to late July (Colvin 1984, Byrd and Rosenburg 1986). Juveniles may remain in the vicinity of the nest site for several weeks before dispersing (Otteni et al. 1972, Smith et al. 1974, Marti 1990). Male may care for fledged young as female begins second clutch. In northern Utah, 71% of all nesting attempts yielded at least one fledgling; reproductive success and productivity were reduced following winters with particularly low temperatures and long periods of deep snow cover (Marti 1994). Breeding density depends on availability of nest sites and on food supply. See Marti (1989) for information on breeding phenology in different areas.

Matures and breeds within its first year (Stewart 1952, Maestrelli 1973, Marti 1990) and sometimes as early as seven months of age (B. Colvin, pers. comm.). It is typically monogamous, but Colvin and Hegdal (1989) reported that as many as 10% of the adult males in their New Jersey study area may be polygynous.
Provincial Reproduction Comments: Clutch size ranges up to 12, with 3-6 eggs being most common (Campbell et al. 1990). The incubation period is normally 30-34 days (Godfrey 1986). Most egg-laying in British Columbia has been documented between early March and early May. Second broods uncommon in temperate areas. Rarely the female will start laying second clutch 75-80 days after the first was begun (Marti 1992, Bunn et al. 1982), sometimes when young of the first brood are still roosting in the nest site (Marti 1968). Once the eggs hatch, the chicks take 8-10 weeks before they fledge. Female does all brooding. Male delivers food items and female provides young with pieces until their are able to swallow prey whole (by about two weeks), then adults merely deliver prey to the nest and depart (Marti 1992). Most individuals appear to breed at one year of age (Marti 1992).
Global Ecology Comments: Individuals range over large areas; mean home range size (based on the minimum home range method (Mohr and Stumpf 1966)) has been reported as 355 ha in southern Texas (Byrd 1982), 757 ha and 921 ha in southwestern New Jersey (Colvin 1984, Hegdal and Blaskiewicz 1984), 414 ha in eastern Virginia (Rosenburg 1986), 850 ha in Virginia (Byrd and Johnston 1991), and 198 ha in western Nebraska (Gubanyi 1989). As much as 5.6 km may be traveled between a nest site and foraging areas, although distances within 1.6 km are more usual (Colvin 1984, Hegdal and Blaskiewicz 1984, Rosenburg 1986). Overlap of individual home ranges is common, particularly where nest sites and prey are abundant. (Smith et al. 1974, Colvin 1984, Rosenburg 1986).

Young disperse widely from natal area, commonly more than 80 km, up to hundreds or 1900 km documented; wide dispersal facilitates colonization of new areas. Hatching-year barn owls have been recovered great distances from natal areas (commonly > 80 km and as much as 1800 km) (Stewart 1952; Soucy 1980, 1985). Although juveniles have been recovered from essentially every compass direction from their natal area, most had traveled in a southerly direction (Stewart 1952). Juveniles in the northern U.S. migrate south but return to nest somewhere within 320 km of their natal sites (Stewart 1952). Most individuals banded as nestlings and later found breeding did so at distances of about 50 km from their natal areas (Marti 1990). Cases of dispersal > 320 km have also been documented. An individual banded as a nestling in southwestern Iowa was recovered as a breeding adult 419 km to the east (Ehresman et al. 1989). A nestling banded in central New Jersey was found nesting in Ohio (B. Colvin, pers. comm.). Extensive banding of nestlings and capture of adults in southwest New Jersey reveals that only a small percentage of nestlings banded within the study area enter the adult population there: 5% of 181 nestlings banded in 1988 were found in the adult population in 1989 (Colvin and Hegdal 1989). Although they may return to breed relatively close to their natal area, individuals frequently become established great distances away. Very successful at colonizing new areas because of this broad dispersal behavior.

Susceptible to starvation during prolonged low temperatures and snow cover (Marti and Wagner 1985). In Utah, most adults survived only 1 breeding season (Marti 1989). Disease, parasites, and predation are natural factors that may in part limit populations. Appears to be resistant to many diseases that infect other raptors (Schulz 1986). In California, diseases documented include tuberculosis, aspergillosis, and trichomoniasis (Schulz 1986). Toxoplasmosis and eastern equine encephalitis have been detected in New Jersey, although no impact to the birds was apparent (Colvin and Hegdal 1986, 1987). Salmonellosis has been recorded in Pennsylvania (Locke and Newman 1970) and New Jersey (Kirkpatrick and Colvin 1986). Kirkpatrick and Colvin (1986) found SALMONELLA-positive nestlings at five of the 25 New Jersey nest sites examined, and reported that all infected young apparently fledged.

Dipteran ectoparasites and lice have been found on owls (Schulz 1986, Kirkpatrick and Colvin 1989). The endoparasites TRYPANOSOMA, CAPILLARIA, and PORROCAECUM have been identified from the feces of New Jersey owls (Colvin and Hegdal 1986).

NON-BREEDING: solitary or in pairs.
Provincial Ecology Comments: Barn Owl population density varies greatly with habitat quality (Marti 1992). Nests are often reused for many years but commonly with high turnover of individual breeders. Immatures commonly disperse in all directions for the natal site. Home ranges may overlap considerably where nest sites and prey species are abundant. Adults are sedentary year-round in northern Utah (Marti 1988). Individuals remain solitary or paired when not breeding. The Great Horned Owl (Bubu virginianus) reportedly preys upon Barn Owls but evidence is slight (Rudolph 1978, Millsap and Millsap 1987). During prolonged low temperature and snow cover Barn Owls are susceptible to starvation (Marti and Wagner 1985, Andrusiak 1994). Most individuals have a short life span, most often less than two years. Mortality rate may be as high as 75% in the first year of life (Marti 1992).
Migration Characteristics:
(Global / Provincial)
 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant:
Y / Y
Y / N
Y / N
na / N
Global Migration Comments: Populations in northern North America are partially migratory; may winter up to several hundred km southward from breeding area, as far as southern Mexico and the West Indies. Long-distance movements (to Mexico) have been recorded also for a nonbreeding adult and nestling banded in Texas; movement of young may represent dispersal rather than migration. There is no evidence of migration in the northern range in Europe, nor in northern Utah (Marti 1989). At Cape May Point, New Jersey, 90% of fall migration was completed between late September and early November (Duffy and Kerlinger 1992). See also Russell et al. (1991) for an account of fall migration at Cape May Point, New Jersey (peak migration was mid- to late October).

Stewart (1952) described it as partly migratory in the Northeast and presents extensive evidence of individuals banded in northern latitudes that were later recovered in southern latitudes. Duffy (1985) reported that large numbers of migrants are captured during fall night trapping at Cape May, New Jersey. Although most captured owls were juveniles, 20% of 171 captures at Cape May were adults (P. Kerlinger, pers. comm.). Most adults migrate past Cape May early in October while hatching-year birds migrate throughout October and early November (Duffy 1985). Recoveries of barn owls banded in the northeastern U.S. indicate that migrant individuals winter chiefly in the southeastern U.S. and Texas (Stewart 1952, Soucy 1980).

Northeastern U.S. Christmas Bird Count data (Stewart 1980, Butcher and Lowe 1990) demonstrate that not all individuals near the northern edge of the range leave for the winter; numerous counts from all northeastern states except Maine, New Hampshire, and Vermont reported barn owls every year. During the winter of 1989- 90, 74% of 35 active Virginia sites visited supported wintering owls (C. Rosenburg, unpubl. data). Although there is an observed migration of both juveniles and adults, many individuals winter within the northeastern U.S. There seem to be no obvious migration patterns (e.g., coastal vs. inland populations, mild winters vs. severe winters) within the northeastern U.S.. However, no investigations have been made into the possible influence of microtine rodent abundance on the percentage of the population which apparently migrates.
Provincial Mobility & Migration Comments: Little is known about sub-national mobility. Immatures may disperse widely from natal site beginning in mid to late summer. Not to be confused for local migration. Colonization of British Columbia appears to have occurred during the 19th century; the first recorded sighting in 1909 near the mouth of the Fraser River. Numbers thought to increase from 1940 to 1980 as a result of mild winters and expansion of suitable agricultural habitat. The species spread through the Fraser Lowlands to Hope and also colonized south-eastern Vancouver Island from Victoria to Naniamo (Campbell et al. 1990). Barn Owls have been observed as far northeast as the Okanagan Valley, as far east as the Creston Valley and as far northwest as Campbell River.
Habitats:
(Type / Subtype / Dependence)
Agriculture / Cultivated Field / Facultative - frequent use
Agriculture / Hedgerow / Facultative - frequent use
Agriculture / Pasture/Old Field / Facultative - frequent use
Anthropogenic / Urban/Suburban / Facultative - occasional use
Forest / Mixed Forest (deciduous/coniferous mix) / Facultative - occasional use
Grassland/Shrub / Antelope-brush Steppe / Facultative - occasional use
Grassland/Shrub / Grassland / Facultative - occasional use
Grassland/Shrub / Meadow / Facultative - occasional use
Grassland/Shrub / Sagebrush Steppe / Facultative - occasional use
Riparian / Gravel Bar / Facultative - occasional use
Riparian / Riparian Forest / Facultative - occasional use
Riparian / Riparian Herbaceous / Facultative - occasional use
Riparian / Riparian Shrub / Facultative - occasional use
Wetland / Marsh / Facultative - occasional use
Global Habitat Comments: BREEDING: Fields of dense grass. Open and partly open country (grassland, marsh, lightly grazed pasture, hayfields) in a wide variety of situations, often around human habitation (AOU 1983). Nests in buildings (church steeples, attics, platforms in silos and barns, wooden water tanks, duckblinds), caves, crevices on cliffs, burrows, and hollow trees, rarely in trees with dense foliage (AOU 1983). Caves, cliff crevices, and cut bank burrows are commonly used in the western U.S., rarely in the east. Uses nest boxes (Marti and Wagner 1985). Reproductive success generally is higher in a properly placed and maintained nest box than in a natural nest cavity.

FORAGING HABITAT: Dense grass fields are the chief foraging habitat, including saltmarsh, wet meadows, lightly grazed pastures, grass hayfields, and recently abandoned agricultural fields (Colvin 1980, 1984, 1985; Rosenburg 1986; Gubanyi 1989). Radiotelemetry studies indicate that these habitats are actively selected (Colvin 1984, Rosenburg 1986, Gubanyi 1989). Furthermore, the quantity and quality of dense grass habitats are significantly correlated with nest activity (Colvin and Hegdal 1988).

Other habitats occasionally used include alfalfa/grass (Colvin 1984), small grain (Ault 1971, Rosenburg 1986), fencelines, and roadsides (Ault 1971, Byrd 1982). In an intensively farmed area in eastern Virginia where grass availability was very low, foraged in small grain, a five-year-old clearcut, barnyards, and a pine (PINUS spp.) plantation used as a blackbird roost (Rosenburg 1986). Cultivated habitats in general are of little importance because of low prey populations and/or dense protective cover (Colvin 1984, Rosenburg 1986).

NESTING HABITAT: This is a cavity-nesting bird which uses natural as well as human-created cavities. Tree cavities are the principal nest site used in most areas of the Northeast (Colvin et al. 1984); those most frequently used are silver maple (ACER SACCHARINUM), American sycamore (PLATANUS OCCIDENTALIS), and white oak (QUERCUS ALBA) (Colvin et al. 1984, Byrd and Rosenburg 1986). Although cut bank burrows and cliff recesses are frequently used in the western U.S. (Otteni et al. 1972, Martin 1973, Rudolph 1978, Millsap and Millsap 1987, Gubanyi 1989), only a few cases of the use of such sites have been reported in the Northeast. R. Ferren (pers. comm.) described nest holes in the steep bluffs on the north and south ends of Block Island, Rhode Island. Recesses in a clay embankment along the Patuxent River in Maryland supported a breeding pair during the late 1980s (S. Smith, pers. comm.). Exposed barrels in a cut bank along the Rappahannock River of eastern Virginia supported approximately 15 nesting pairs in the late 1970s (S. Doggett, pers. comm.). A wide variety of human-made "cavities" are used as nest sites. Large platforms within barns and silos, tunnels dug into silage in roofed or topless silos, cavities among hay bales stored inside barns, barn cupola shelves, wooden water tanks, and offshore duckblinds are frequently used; feed bins, church steeples and belfries, platforms within commercial and industrial buildings (e.g., warehouses, grain elevators, mills, factories), attics of abandoned or occupied houses, ledges within chimneys, platforms beneath bridges, and World War II cement watch towers are occasionally used (Stotts 1958, Scott 1959, Reese 1972, Klaas et al. 1978, Soucy 1979, Bunn et al. 1982, Hegdal and Blaskiewicz 1984, Colvin 1984, Byrd and Rosenburg 1986, Matteson and Petersen 1988, Parker and Castrale 1990). In addition, nest boxes are readily used (Otteni et al. 1972, Marti et al. 1979, Soucy 1980, Ziesemer 1980, Colvin et al. 1984, Cook 1985, Schulz 1986, Byrd and Rosenburg 1986, Bendel and Therres 1988, Parker and Castrale 1990).

NON-BREEDING: In winter often roosts in dense conifers; also roosts in nest boxes if available (Marti and Wagner 1985).
Provincial Habitat Comments: Prefer low elevation open country; especially agricultural areas, such as open fields, grasslands, farmsteads and orchards, sometimes along edges of open woodlands and grassy estuaries and occasionally spotted in suburban areas. Use of suitable foraging habitat is limited by nest cavity requirements. Most often nests are located in human-made structures such as in wooden barns, concrete silos, church spires, airport hangers, water towers, bridges and nest boxes (Marti 1979, Andrusiak 1994). Natural sites include hollow tree cavities, cliffs, river banks and disused hawk nests (Campbell et al. 1990). The most common nests are on wooden platforms high in old wooden barns.
Food Habits: Carnivore: Adult, Immature
Global Food Habits Comments: Eats mainly small mammals, especially voles (MICROTUS spp.). BLARINA, THOMOMYS, SPERMOPHILUS, PEROGNATHUS, DIPODOMYS, and PEROMYSCUS can be locally important. Birds can be taken when small mammals are scarce; introduced rodents are important in some urban areas and (with bats and birds) in the West Indies. In northern and eastern North America, the shrew (Soricidae) component of diet has declined over the past several decades; in the northern and central range, percentage of exotic rats and mice has increased (Clark and Bunck 1991).

Numerous pellet analyses throughout north temperate North America and Europe have identified voles as the primary prey (Ticehurst 1935; Wilson 1938; Pearson and Pearson 1947; Wallace 1948; Phillips 1951; Boyd and Shriner 1954; Glue 1967, 1974; Smith et al. 1972; Marti 1973; Webster 1973; Jackson et al. 1976; Lovari et al. 1976; Dexter 1978; Bethge and Hayo 1979; Colvin 1980, 1984; Hegdal and Blaskiewicz 1984; Cook 1985; Colvin and McLean 1986; Rosenburg 1986; Campbell et al. 1987; Feldhamer et al. 1987; Parker 1987; Hammerson 1988; Marti 1988). The meadow vole (MICROTUS PENNSYLVANICUS) is the most important prey animal in the northeastern U.S. and the short-tailed shrew (BLARINA BREVICAUDA) is an important secondary prey. By frequency, meadow voles typically comprise 60-90% of the diet (Boyd and Shriner 1954, Jackson et al. 1976, Colvin 1984, Cook 1985, Rosenburg 1986, Hammerson 1988). The marsh rice rat (ORYZOMYS PALUSTRIS) can be an important prey animal in coastal areas of southeastern North America (Jemison 1962, Blem and Pagels 1973, Jackson et al. 1976, Colvin 1984, Feldhamer et al. 1987). In the southern U.S., the cotton rat (SIGMODON HISPIDUS) is the primary prey (Baumgartner and Baumgartner 1944, Parmalee 1954, Otteni et al. 1972, Hamilton and Neill 1981, Byrd 1982, Baker 1986, Marra et al. 1989). Colvin (1984) concluded that barn owls seek prey of a particular size (approximately 40-60 g), which provides the most energy efficient diet.

Shows greater diet diversity: 1) in areas with relatively low microtine or cotton rat availability (Ticehurst 1935; Hawbecker 1945; Pearson and Pearson 1947; Glue 1967, 1974; Blem and Pagels 1973; Marti 1974; Bauer 1983; Colvin 1984; Lenton 1984; Colvin and McLean 1986; Rosenburg 1986; Parker 1987; Campbell et al. 1987); 2) during times of poor microtine availability (Fitch 1947, Wallace 1948, Glue 1967, Otteni et al. 1972, Webster 1973, Marti 1974, Jackson et al. 1976, Bethge and Hayo 1979, Baker 1986); and 3) when nonmicrotine prey are readily available (Evans and Emlen 1947, Sage 1962, Carpenter and Fall 1967, Smith et al. 1972, Klaas et al. 1978, Byrd 1982, Fritzell and Thorne 1984, Rosenburg 1986, Jentzsch 1988). These studies identified birds (mostly blackbirds and sparrows), short-tailed shrews, least shrews (CRYPTOTIS PARVA), house mice (MUS MUSCULUS), and Norway rats as relatively important prey in such situations.

The foraging behavior has been well studied (Colvin 1980, 1984).

Typical foraging is done with a relatively low quartering flight which includes frequent hovering intervals (Honer 1963, Haverschmidt 1970, Burton 1973, Karalus and Eckert 1974, Marti 1974, 1989, Rudolph 1978, Bunn et al. 1982, Mikkola 1983, Rosenburg 1986). Some individuals also hunt rather frequently from a perch, especially along field edges (Byrd 1982, Rosenburg 1986).

In North America this owl is highly nocturnal (Colvin 1984, Rosenburg 1986); it has extremely keen hearing (Payne 1971, Konishi 1973) and night vision (Dice 1945, Marti 1974). Its ability to capture prey by hearing alone (Payne 1971) is especially advantageous for hunting animals such as voles and shrews which are often concealed from view as they travel in runways beneath grass cover.
Provincial Food Habits Comments: Barn Owls prey almost exclusively on small mammals. Young are fed same diet as adults (Smith et al. 1974). Townsend's Vole (Microtus townsendii) is the single most important prey species, found to constitute 63-85% of the annual diet (Campbell et al. 1987). Most hunting is done in low quartering flights at about 1.5-4.5 m above the ground in open habitats (Bunn et al. 1982). Prey detected by excellent low-light vision (Marti 1974) and hearing (Knudsen 1981). Ability to locate prey by sound is excellent allowing capture of prey hidden by vegetation or snow.
Global Phenology: Crepuscular: Adult, Immature
Nocturnal: Adult, Immature
Global Phenology Comments: Hunts mostly at night, from about 1 hour after sunset to about one hour before sunrise (Marti 1989).
Provincial Phenology:
(1st half of month/
2nd half of month)
Provincial Phenology Comments: Depending on vole numbers, Barn Owls may breed at any time of the year. Winter breeding is uncommon.
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 16/ / 490
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: RESIDENT: In the Americas from southern Canada and the northern U.S. south to southern South America, Greater Antilles (except Puerto Rico), and Lesser Antilles (AOU 1983, Marti 1992). Variable occurrence within this range, with low densities at northern periphery (Marti 1992). In Old World from British Isles, southern Russia, and southern Siberia south through Eurasia and Africa to southern Africa, Madagascar, East Indies, and Australia. Populations in northern North America are partially migratory. Introduced (1958 and later) in Hawaii; now on all main islands (AOU 1983).
 
Authors / Contributors
Global Information Author: Hammerson, G.
Last Updated: Mar 30, 1995
Provincial Information Author: Manning, T. and J.M. Cooper
Last Updated: Jan 23, 2005
   
References and Related Literature
Altwegg, R., et al. 2003. Variation and covariation in survival, dispersal, and population size in barn owls Tyto alba. J. Animal Ecol. 72:391-399.
American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
Andrusiak, L.A. 1994. Nesting and roosting habitat and breeding biology of the Barn Owl, Tyto alba, in the lower mainland of British Columbia. M.Sc. Thesis, Univ. of B.C., Vancouver, BC.
Andrusiak, L.A., and K.M. Cheng. 1997. Breeding biology of the Barn Owl (Tyto alba) in the Lower Mainland of British Columbia. pp. 38-46 in J.R. Duncan, D.H. Johnson, and T.H. Nicholls, eds. Biology and conservation of owls in the Northern Hemisphere. Second Int. Symp., Winnipeg, MB. USDA For. Serv. Gen. Tech. Rep. NC-190.
Bent, A. C. 1938. Life histories of North American birds of prey. Part 2. U.S. Nat. Mus. Bull. 170. 482 pp., 92 pls.
Berger, A. J. 1981. Hawaiian Birdlife. Second Edition. University Press of Hawaii, Honolulu, Hawaii. xv + 260 pp.
British Columbia Ministry of Forests. 2001. Forest health conditions. 2000. Aerial overview survey summary. Online. Available: http://www.for.gov.bc.ca/hfp/forsite/overview/2000table.htm
Bunn, D. S., A. B. Warburton, and R. D. S. Wilson. 1982. The barn owl. Buteo Books, Vermillion, South Dakota. 246 (or 264?) pp.
Bunn, D.S., A.B. Warburton, and R.D.S. Wilson. 1982. The Barn Owl. Buteo Books, Vermillion, SD. 264pp.
Byrd, M. A., and D. W. Johnston. 1991. Birds. Pages 477-537 in K. Terwilliger, coordinator. Virginia's endangered species: proceedings of a symposium. McDonald and Woodward Publ. Co., Blacksburg, Virginia.
Campbell, R.W., D.A. Manuwal, and A.S. Harestad. 1987. Food habits of the common Barn Owl in British Columbia. Can. J. Zool. 65:578-86.
Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser, and M.C.E. McNall. 1990b. The Birds of British Columbia Vol. 2: Nonpasserines: Diurnal Birds of Prey through Woodpeckers. Royal British Columbia Museum, Victoria, BC.
Cannings, R.J. 1998. The Birds of British Columbia - a taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria, Wildl. Bull. B-86. 266pp.
Clark, D. R., Jr., and C. M. Bunck. 1991. Trends in North American small mammals found in common barn-owl (TYTO ALBA) dietary studies. Can. J. Zool. 69:3093-3102.
Clark, R. J., D. G. Smith, and L. H. Kelso. 1978. Working bibliography of owls of the world. National Wildlife Federation, Sci. & Tech. Ser. No. 1. 336 pp.
Colvin, B.A. 1985. Common Barn-Owl population decline in Ohio and the relationship to agricultural trends. J. Field Ornithol. 56:224-235.
COSEWIC. 2001d. COSEWIC assessment and update status report on the Barn Owl Tyto alba in Canada. Comm. on the Status of Endangered Wildl. in Can. Ottawa. vii + 11pp.
Demarchi, M.W. and M.D. Bently. 2005. Best Management Practices for Raptor Conservation during Urban and Rural Land Development in British Columbia. B.C. Minist. of Environ., Victoria, B.C. MoE BMP Series.
Duffy, K., and P. Kerlinger. 1992. Autumn owl migration at Cape May Point, New Jersey. Wilson Bull. 104:312-320.
Eckert, Allan W. 1978. The Owls of North America. Weather-vane Books, New York. 278 pp.
Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1992. Birds in Jeopardy: the Imperiled and Extinct Birds of the United States and Canada, Including Hawaii and Puerto Rico. Stanford University Press, Stanford, California. 259 pp.
Evers, D. C. 1992. A guide to Michigan's endangered wildlife. Univ. Michigan Press, Ann Arbor. viii + 103 pp.
Fisher, A.K. 1893. The hawks and owls of the United States in their relation to agriculture. Washington U.S. Dept. of Agriculture Bull. no. 6. 210 pp.
Godfrey, W.E. 1986. The Birds of Canada, rev. ed. Natl. Mus. Can., Ottawa, ON. 595pp.
Gustafson, M. E. 1991. Diet and habitat selection in Ohio nesting barn owls (TYTO ALBA). M.S. thesis, Ohio State Univ. ix + 92 pp.
Hands, H. M., R. D. Drobney, and M. R. Ryan. 1989. Status of the common barn-owl in the northcentral United States. Missouri Coop. Fish Wildl. Res. Unit Rep. 19 pp.
Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
Harrison, H. H. 1979. A field guide to western birds' nests. Houghton Mifflin Company, Boston. 279 pp.
Hegdal, P.L., and R.W. Blaskiewicz. 1984. Evaluation of the potential hazard to Barn Owls of Talon (brodicacoum bait) used to control rats and house mice. Environ. Toxicol. Chem. 3:167-179.
Henny, C.J. 1969. Geographical variation in mortality rates and production requirements of the Barn Owl (Tyto alba ssp.). Bird-Banding. 40:277-290.
Herkert, J. R., editor. 1992. Endangered and threatened species of Illinois: status and distribution. Vol. 2: Animals. Illinois Endangered Species Protection Board. iv + 142 pp.
Johnsgard, P. 1988. North American owls: biology and natural history. Smithsonian Inst. Press. 336 pp.
Kirk, D. A., D. Hussell, and E. Dunn. 1995. Raptor population status and trends in Canada. Bird Trends (Canadian Wildlife Service) 4:2-9.
Kirk, D.A. 1999b. Update COSEWIC status report on the Barn Owl Tyto alba in Canada. Comm. on the Status of Endangered Wildl. in Can. Ottawa. 11pp.
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1995. Species Summary: Tyto alba. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Sep 16, 2021).