Species: Tyto alba

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