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OF OWLS
The
Strigiformes (Owls) are an
order of birds of prey, comprising 200 extant
species. Most are solitary, and
nocturnal, with some exceptions (e.g. the Burrowing Owl).
Owls mostly hunt small mammals, insects, and other birds,
though a few species specialize in hunting fish. They are
found in all regions of the Earth except Antarctica, most of
Greenland, and some remote islands. Though owls are
typically solitary, the literary collective noun for a group
of owls is a parliament.
The living owls are divided into
two families, the typical owls, Strigidae, and the
barn-owls, Tytonidae.
Description
Owls have large forward-facing eyes
and ear-holes, a hawk-like beak, a flat face, and usually a
conspicuous circle of feathers around each eye called a
facial disc.
Although owls have binocular vision, their large eyes are
fixed in their sockets, as with other birds, and they must
turn their entire head to change views.
The smallest owl is the Elf Owl (Micrathene
whitneyi),
at as little as 31 g (1.1 oz) and 13.5 cm (5.3 inches). Some
of the pygmy owls are scarcely larger. The largest owls are
two of the eagle owls, the Eurasian Eagle Owl (Bubo
bubo) and Blakiston's Fish Owl (Bubo
blakistoni), which may reach a
size of 60-71 cm (28.4 in) long, have a wingspan of almost 2
m (6.6 ft), and weight of nearly 4.5 kg (10 lb).
Owls are far-sighted, and are
unable to see anything clearly within a few inches of their
eyes. Caught prey can be felt by owls with the use of
filoplumes, which are small hair-like feathers on the beak
and feet that act as "feelers". Their far vision,
particularly in low light, is exceptionally good. They can
turn their head 135 degrees in either direction; they can
thus look behind their own shoulders.
Different species of owls make
different sounds; the wide range of calls aids owls in
finding mates or announcing their presence to potential
competitors, and also aids ornithologists and birders in
locating these birds and recognizing species. The facial
disc helps to funnel the sound of prey to their ears. In
many species, these are placed asymmetrically, for better
directional location (Cotty, 2008).
Owl eggs are usually white and almost
spherical, and range in number from a few to a dozen,
depending on species. The eggs are laid in intervals of 1–3
days and do not hatch at the same time. This accounts for
the wide variation in the size of sibling nestlings. Owls do
not construct nests but rather look for a sheltered nesting
site or an abandoned nest, in trees, underground burrows, or
in buildings, barns and caves.
Behavior
Most owls are nocturnal, actively
hunting for prey only under the cover of darkness. Several
types of owl, however, are crepuscular, or active during the
twilight hours of dawn and dusk; one example is the pygmy
owl (Glaucidium).
A few owls are also active during the day; examples are the
Burrowing Owl (Speotyto
cunicularia) and the
Short-eared Owl (Asio flammeus).
The time at which an owl hunts is correlated with the colour
of its eyes: dark brown or black eyes indicate nocturnal
activity, orange indicates dawn or dusk, and owls with
yellow eyes are diurnal and hunt during the day.
There are exceptions, however, so the colour of an owl's
eyes is not in itself a reliable indicator of its active
hours.
Much of the owl's hunting strategy
depends on stealth and surprise. Owls have at least two
adaptations that aid them in achieving stealth. First, the
dull coloration of an owl's feathers can render them almost
invisible under certain conditions. Secondly, serrated edges
on the leading edge of the owl's remiges muffle the owl's
wingbeats, allowing its flight to be practically silent.
Some fish-eating owls, where this silence is of no
evolutionary advantage, lack this adaptation.
Once prey has been captured, the
owl's sharp beak and powerful talons allow it to kill its
prey before swallowing it whole (unless it is too big).
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 often sold by companies to schools
to be dissected by students as a lesson in biology and
ecology, because they are plentiful and easy to interpret.
At Falconry-UK we have
twelve different species of Owls.
Most of our Owls are Hand
Reared.
Please click on the
Species Name below to view photographs or the Name of Falcon
to view them individually.
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