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NATURE HAPPENINGS - February 2007


The Neighborhood Prowler
by Damian Fagan

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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