Sully
Sully is a male Western Screech Owl (Megascops
kennicottii) who came to the WSU Veterinary Teaching
Hospital in September of 2009. He had an injury to his right
wing, most likely caused by a collision with a car. The wing was
dislocated at the shoulder, effectively permanently immobilizing
it. Since Sully no longer has the use of that wing, he is unable
to fly and is not releasable.
There are 3 types of screech owl in the United States. The
Western Screech Owl – found West of the Rocky Mountains, the
Eastern Screech Owl (Megascops asio) – found East of
the Rocky Mountains, and the Whiskered Screech Owl (Megascops
trichopsis) – found in the Southwestern states and Mexico.
The Eastern screech owl is similar in color and size to the
Western, but the Western has a much darker bill color. The
Whiskered screech owl is smaller than the other two and has an
orange tinge to its eye color (the others have yellow eyes). The
screech owls have color patterns that allow them to blend in
perfectly with the trees in their environment. They also all
have “ear tufts” on the top of their head (like the Great Horned
Owl) which have nothing to do with ears, but are actually just
longer feathers that can be raised or lowered. Contrary to their
names, screech owls don’t screech. Instead they have a trilling
"hoo-hoo-hoo" that often starts out slower then speeds up – kind
of like a bouncing ball. Sully is one of the most vocal birds in
the club, and greets everyone with a demanding "Whooo!?".
Western screech owls live in riparian zones (the green,
vegetated areas on each side of streams and rivers) or
urban/suburban areas with mixed coniferous and deciduous trees.
They are cavity nesters, nesting in tree hollows or nesting
boxes.
Screech owls are (primarily) nocturnal and hunt mostly small
rodents like mice. However, they are opportunistic and will also
hunt amphibians, reptiles, small fish, insects, bats and small
birds. Like all owls, they have a facial disk consisting of
stiff feathers around the beak and eyes that direct sound back
to their asymmetrically placed ears (the left is more up and
forward and the right is down and back). This adaptation allows
owls to locate prey by triangulating the source of a sound. Some
owls rely more on sound than others. The screech owl has very
large eyes in proportion to its facial disk. This tells you that
they actually depend more on their vision for locating prey
(although hearing is still important). Owls with a larger,
more defined facial disk would likely depend more on their
hearing (for example, the barn owl).
All owls have several characteristics that make them unique
among raptors. For example, the front edge of their flight
feathers is serrated like a bread knife. This breaks up air
turbulence and allows them to fly completely silently. There are
two purposes for this – for one, owls do not want their prey to
hear them coming. The second reason is that owls depend so much
on their hearing that any noise from their wings would hinder
their hunting ability.
Another characteristic of owls is the large size of their eyes.
They are so large, in fact, that there is no space for extrinsic
muscles to move the eyes. As a result, there is a bony ring
around each eye that fixes them in place. While humans and most
mammals can look to the left and right with their eyes without
turning the head, owls cannot. To compensate for the lack of eye
movement, owls have twice as many vertebrae in their neck as
mammals – we have 7, they have 14. This allows them to turn
their head completely backwards – and beyond! While they cannot
rotate their head 360 degrees in each direction as many people
believe, they can rotate it about 270 degrees each way. Because
of the large number of vertebrae, owls can also extend their
neck way up to stand taller.
Owls also have unique feet relative to most other raptors.
Instead of standing with three toes in front and one toe
pointing backwards (known as the anisodactyl arrangement), they
stand with two toes forward, and two pointing backwards (known
as a zygodactyl arrangement). However, while hunting, owls have
the ability to rotate their third toe forward into an
anisodactyl arrangement.
Unlike other raptors, owls have no crop for food storage. They
often swallow their food whole or in large chunks, and it goes
directly to the stomach. In the stomach, a pellet (or cast) is
formed from fur, bones, and other indigestible material. The
pellet is then regurgitated 10 or more hours later. Larger owl
pellets can be easily dissected to find the bones of their most
recent prey.
