Just
before sleep overtakes me, I hear the soft sounds of
a western screech owl in our neighborhood. The calls
pierce the quiet of this February night and the descending
whistled notes are unmistakable, even in my sleepy
state.
The western screech owl is one of the smaller owls to
inhabit Canyon Country. This cavity nesting bird occurs
in cottonwood groves that line streams and rivers in
and around Moab. These birds may also find nest sites
in orchard trees, mulberries, natural tree cavities,
saguaro cacti (Arizona, not Moab), building crevices,
or abandoned magpie nests. Though the birds often use
abandoned woodpecker holes, they will also nest in artificial
nest boxes.
My friend Steve Kuhn has placed several nest boxes for
owls and wood ducks up in his neighborhood in Spanish
Valley. Even though he has only had an owl roosting in
one box, he still has hopes that a nesting pair of owls
will take up residency.
Fossil Record
Historically, the screech owl is known from Pleistocene
fossil records. This time period, ranging from about
11,000 to 2 million years ago saw a proliferation of
small mammals carried over from the Miocene (roughly
25 to 10 million years ago). Associated with this diversity
of small rodents was a diversification of predators such
as the owls that we observe today.
Though the fossilized family tree is incomplete at best,
it is difficult to imagine owls living during the great
Age of the Dinosaurs. Just imagine how big these owls
would have had to be to take on this prey base!
Features of the Creatures
The western screech owl’s scientific name is Otus
kennicottii. Otus is Latin for “horned owl” and
kennicottii honors Robert Kennicott, an ornithologist
who collected owl specimens in Canada and Alaska in the
mid-1800s.
At 7-10 inches tall, the western screech owl does not
seem like an imposing predator. However, size is relative
to these birds, as they will take a wide variety of prey
from insects to small rodents, amphibians, fish, reptiles,
and mammals their own size.
Mainly nocturnal, these birds spend the day perched motionlessly
on a limb or within a cavity. Always on the alert, these
owls will rotate their heads to observe the source of
any disturbance. Because an owl’s eyes are fixed
in their sockets – they can’t move side to
side like a human’s eye – the birds must
rotate their head to focus on something else.
Their exceptional eyesight is due to the owl’s
iris that can enlarge or stop down depending upon the
amount of light entering the eye. This contracting and
expanding allows the owls to see very well in all light
conditions. The coolest thing about owl optics is that
each eye can react independently of the other. For humans,
that would often indicate one has suffered some head
trauma.
Perhaps the afflicted individuals believe that owls can
rotate their heads in a 360° arc. The rapid movement
of their heads gives the illusion of that the head can
swivel around in a circle. But these owls can only rotate
their heads about 270° (still impressive) and this
is possible because of numerous neck vertebrae.
So before you call it a night, step outside and spend
a moment listening for the telltale song of a screech
owl. Maybe you’ll sleep better knowing that a welcomed
nighttime prowler is out and about in your neighborhood. |
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