The feathers making up this disc can be adjusted to sharply focus sounds from varying distances onto the owls' asymmetrically placed ear cavities.

Owls have binocular vision, but they must rotate their entire heads to change the focus of their view because, like most birds, their eyes are fixed in their sockets.

Owls have 14 neck vertebrae — humans have only seven — and their vertebral circulatory systems are adapted to allow them to rotate their heads without cutting off blood to the brain.

[6] Around the same diminutive length, although slightly heavier, are the lesser known long-whiskered owlet (Xenoglaux loweryi) and Tamaulipas pygmy owl (Glaucidium sanchezi).

Owl plumage is generally cryptic, although several species have facial and head markings, including face masks, ear tufts, and brightly colored irises.

These markings are generally more common in species inhabiting open habitats, and are thought to be used in signaling with other owls in low-light conditions.

[12] The degree of size dimorphism varies across multiple populations and species, and is measured through various traits, such as wing span and body mass.

[14] This has also been observed in other predatory birds,[13] which suggests that owls with smaller bodies and long wing chords have been selected for because of the increased agility and speed that allows them to catch their prey.

[citation needed] Another popular theory suggests that females have not been selected to be smaller like male owls because of their sexual roles.

[15] If owls are still evolving toward smaller bodies and longer wing chords, according to V. Geodakyan's Evolutionary Theory of Sex, males should be more advanced on these characters.

Most owls live a mainly nocturnal lifestyle and being able to fly without making any noise gives them a strong advantage over prey alert to the slightest sound in the night.

[26] Historically, they would switch to hunting indoors in wet weather, using barns and other agricultural buildings, but the decline in the numbers of these structures in the 20th and 21st centuries has reduced such opportunities.

[24] The lack of waterproofing means that barn owls are also susceptible to drowning, in drinking troughs and other structures with smooth sides.

Owls are part of a small group of birds that live nocturnally, but do not use echolocation to guide them in flight in low-light situations.

[29] This ability keeps bodily movement at a minimum, thus reduces the amount of sound the owl makes as it waits for its prey.

Owls are regarded as having the most frontally placed eyes among all avian groups, which gives them some of the largest binocular fields of vision.

The beak of the owl is short, curved, and downward-facing, and typically hooked at the tip for gripping and tearing its prey.

[36] The coloration of the owl's plumage plays a key role in its ability to sit still and blend into the environment, making it nearly invisible to prey.

The snowy owl (Bubo scandiacus) appears nearly bleach-white in color with a few flecks of black, mimicking their snowy surroundings perfectly, while the speckled brown plumage of the tawny owl (Strix aluco) allows it to lie in wait among the deciduous woodland it prefers for its habitat.

Scientists studying the diets of owls are helped by their habit of regurgitating the indigestible parts of their prey (such as bones, scales, and fur) in the form of pellets.

These "owl pellets" are plentiful and easy to interpret, and are often sold by companies to schools for dissection by students as a lesson in biology and ecology.

[45] The Messelasturidae, some of which were initially believed to be basal Strigiformes, are now generally accepted to be diurnal birds of prey showing some convergent evolution toward owls.

At times, Chamunda (fearsome form of Chandi) is depicted seated on an owl, her vahana (mount or vehicle).

[63][64] T. F. Thiselton-Dyer, in his 1883 Folk-lore of Shakespeare, says that from the earliest period it has been considered a bird of ill-omen," and Pliny tells us how, on one occasion, even Rome itself underwent a lustration, because one of them strayed into the Capitol.

Ovid, too, constantly speaks of this bird's presence as an evil omen; and indeed the same notions respecting it may be found among the writings of most of the ancient poets.

Sometimes owls are said to carry messages from beyond the grave or deliver supernatural warnings to people who have broken tribal taboos.

[citation needed] The Ojibwe tribes, as well as their Aboriginal Canadian counterparts, used an owl as a symbol for both evil and death.

[79] For example, in January 2013, a man from Inverness, Scotland suffered heavy bleeding and went into shock after being attacked by an owl, which was likely a 50-centimetre-tall (20 in) eagle-owl.

TRAFFIC commended the Department of Wildlife and National Parks in Malaysia for the raid that exposed the huge haul of owls.

[83] In addition to hunting, other threats to owl populations are habitat loss, pesticides, viruses, and vehicle collisions.