This article is part of
Wilderness Way
VOLUME 9, ISSUE 3.
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Who is the Owl?
by Cpl. Geoffrey Angle, USMC
Our group had just begun their hike, winding our way
alongside a creek, whose clear, shaded waters slowly
trickled westward towards the city by the sea. One student
stooped down to investigate a stand of mugwort, a prolific
local plant useful in preventing rashes from poison oak and
helpful in starting fires by primitive methods. He found a
large feather. After a short discussion, the class
determined it was from an owl.
A few moments later, the instructor paused on the trail, pointed across the creek, and exclaimed, "Look at that!" There in the dirt on his back lay the carcass of the feather's owner, an enormous great horned owl. The class gathered quickly around the bird, awed by its size and incredible camouflage, which even when sprawled out on the ground hid it from most of the class on the other side of the creek. As a group, we began to discuss in earnest this amazing find.
Owls range all over the world with the exception of Antarctica, adapting to an extreme variety of environments. Most are strictly nocturnal in their habits, though some species are crepuscular (active at dawn and dusk), and some (though few) are diurnal as well. Today there are about 181 owl species, and these are divided into two families: the Strigidae, typical or true owls, and the Tytonidae, known as the barn owls. Their size can range from the diminutive, such as the elf owl of the American southwest, a mere 5 inches long, with a wing-span of 15 inches to the magnificence of the great northern eagle owl, with a length of 28 inches and a wingspan of 48 inches found throughout Europe and Asia.
Unique Eyes
All owls have a unique physiology specifically adapted to hunting their prey. Characteristics that all owls share are their large eyes and ears, downward curving beaks, muffled feathers, and sharp talons. It is a design created to gather light and sound, while keeping their own presence hidden, a design of stealth and power.
Owls share the same type of binocular vision that humans possess (though with a slightly more restricted field of view), however, that is where the similarities end. The owl's optical structures are like wide tunnels, open to receive as much ambient light as possible. In order to do so, nature has modified the typical spherical shape of an eye and made it tubular, securely fastened and supported by boney structures called sclerotic rings that lock the eyes into a forward facing position. The large retinas at the back of the eyes contain a higher ratio of light collecting rod cells as opposed to color sensitive cone cells, enabling extreme sensitivity to light and movement, but dulling its sense of color to near monochrome. (People can gain a dim appreciation of this when observing at night utilizing their peripheral vision.)
If the eyes are like tunnels, the face of the owl could be likened to a radar dish. Its purpose is to collect and canalize sound towards the large, hidden ears on the sides of its head. To prevent sound deflection and visual obstruction, the owl's sharp beak curves downwards, and facial muscles can manipulate the facial disc to assist in hearing. A fascinating adaptation is the asymmetrical placement of the ears on the sides of the skull. This difference in placement allows the owl to detect the minute difference between the time sound reaches one ear and then the other. Turning its head towards the side to hear it first, once the ears are receiving the sound simultaneously, the owls forward facing eyes will be gazing straight into the sound's source.
With the amazing visual and auditory acuteness developed in owls, an interesting sacrifice was made. Owls have a notoriously poor sense of smell that makes for a surprising common prey for the great horned owl: skunks.
Silent Feathers
Covering the bird's body are different types of feathers
for insulation, for preening, for tactile sensitivity, and
of course, for flying. Unique among owls are those feathers
that allow for silent flight. The primary wing feathers, the
20 feathers mainly responsible for lift, have what is
referred to as a comb on the cutting or leading edge. The
aerodynamics of this forward facing ridge help to disrupt
the noise of normal turbulence, breaking it down into
microturbulences, effectively muffling the sound of flight.
This is equally important to conceal the owl from its
intended prey, as well as to reduce the interfering ambient
noise of its own movement that would be a detriment to its
method of target acquisition.
Powerful Feet
The owl has powerful feet with four toes and very sharp
claws. A rough knobby surface provides traction on both prey
and perch, and a mechanical adaptation in the foot enables
the owl to grip firmly without muscular exertion. When in
flight, three toes face forward and one toe trails behind.
How-ever, when on final approach during a hunt, the
flexibility of its outer third toe enables the owl to spread
its feet like the letter "X" or "K", so
that as it thrusts its feet forward and pulls its head to
the rear for the kill. The maximum surface area will collide
with its victim, and simultaneously minimize the shock of
impact on the bird itself.
Fearless Defenders
Owls will fearlessly defend their nests and young from
intruders, including killing other encroaching species of
owls. One account tells of a pair of children who discovered
a nest site near their Ohio farmhouse and decide to rob it
of its young. Keeping their theft a secret, the head of the
household had no idea why his "crazy ole' wife"
was complaining about a monstrous bird attacking her while
she was hanging up the laundry to dry. Stepping out the
front door simply to appease his wife, he was promptly
knocked flat on his back from the dive-bomb attack of an
enraged great-horned owl, resulting in two black eyes for
him, and some sad days ahead for two very sorry children...
Camouflage
The camouflage of these remarkable birds makes them
notoriously hard to spot during the day. You can still
incorporate the skills of tracking and awareness to discover
their whereabouts. Paul Rezendes, noted photographer and
tracker, notes that the owl's digestive system produces
obvious ground sign in the form of pellets. These pellets
are actually the regurgitated form of the undigested parts
of its prey, consisting mainly of hair and tiny bones. These
pellets can range in size from 1-3/8 inches up to 4 inches
and are an elongated oval shape. Digested matter passes
through the owls system to be defecated as uric acid in a
form sometimes known as whitewash. Owls cannot feed again
until its pellet has been expelled. With digestion taking as
long as ten hours, you could find several pellets along with
whitewash. You might only need to look up to find an owl's
favorite roost. Ac-cording to Rezendes' observations, a
person can differentiate between owl pellets and the pellets
expelled by other raptors simply by noting the proliferation
of small bones mixed with the hair. Other birds of prey,
such as the red-tailed hawk, have more powerful digestive
secretions that can dissolve small bones. In an owl's
pellet, sometimes the entire skull of prey species will
remain intact. Furthermore, note the absence of fecal matter
and musky odor to know that you are not examining the scat
of a coyote or fox!
Another popular method of locating owls amongst birders is to lure owls with their calls at night. Many, but not all, owls' hoot, and calls can vary from tremeling whistles to barks or from purrs to screams. It is the barn owl's horrifying scream and occupation of old buildings that has led many to believe ghosts or banshees haunt certain places!
Folklore
Owls have a frightening mystique in culture and folklore,
often being associated with death. Seeing an owl in unusual
circumstances is often thought to be an omen that someone
the observer knows is going to die. If an owl remained
around the home site of some aboriginal tribes of Australia,
it meant there would be a death in the family. To the
ancient Apache Indians of the United States, even a
significant dream of an owl was a sign of impending death.
The superstition of many Indian tribes forbid-ding whistling
at night may stem from a similar belief to that of the Cree,
who believed that whistles from the Boreal owl were summons
from spirits.
The Kwakiutl of the northwestern U.S. believed owls were the souls of human beings, the Mojave of the southwest believed the birds to be a step towards final realization in human reincarnation. Echoed in other tribes of Australia, the owl was thought to be the soul of a woman, someone's mother or sister.
However, not all cultures beliefs are so grim. The Dakota Hidatsa and Tlingit Indians believed the owl to be a protective spirit. Hooting-like owls when charging forward into combat, the Tlingit both spurned them-selves on and sounded fear into the opposing side. And in the dreams of the Lene Lenape Indians of modern New Jersey, the appearance of an owl meant its animal spirit would be a totemic guardian, of great benefit to that person's life.
Dealing with Death
Back in the Angeles National Forest it was determined
that its intended prey had killed the great horned owl. A
large hole had been torn into its right flank, and although
ants had already gathered, the blood had not yet dried, so
the bird had been mortally wounded sometime during the
previous night.
After the discussion concluded, some of the Native
Americans in the group removed some of the large primary
wing feathers of the bird to make use of in arrow fletching,
small fans, ceremonial items, or as totems. A shallow grave
was scraped out where the bird was originally found, and his
body put to rest with his head facing towards the west,
towards where the sun would set at the end of the day.
Someone produced some tobacco, and after thanking the owl
for his gifts, the tobacco offering was placed in the grave
with a short prayer and the dirt filled in, returning him to
the earth.
