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Tucson Audubon Society
Dastardly Duos
Western and Whiskered Screech-Owls
by Larry Liese
Illustrations by George C. West
(Article first appeared in the May-June 2002 Vermilion Flycatcher newsletter.
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of Tucson Audubon.
It’s breeding season again for most birds, and one group of birds that
become easier to tell apart in this season is owls. Owls are everybody’s
favorite; that is, everybody’s favorite for those who get to see one.
Not only are the nocturnal owls easy to miss as one passes by them during
the day, but some of the darn things seem to look alike as well!
Fortunately, their calls are distinctive, and telling them apart is a
matter of familiarity.
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This month’s duo is a pair of small nocturnal owls that look similar but have different calls and habitat preferences, though they can occur side by side in the lower parts of canyons where the desert gives way to oaks and sycamores.
The Western Screech-Owl (Otus kennicottii) occurs year-round in much of the western U.S. in a wide variety of habitats. In fact, this is the owl I see most often in my backyard here in Tucson! They like wooded/semi-open habitat in canyons, desert mesquites, wooded suburbs; almost anywhere except extreme desert and higher elevations.
Our second player of the evening is the Whiskered Screech-Owl (Otus trichopsis). Bristles on the ends of its facial-disc feathers give it its name, but these are difficult to see. This owl is much more selective in its habitat choice, preferring canyons with dense woodlands of oak, pine/oak, and sycamores, from 3500 to 7000 feet, but generally above 5000 feet elevation.
Visual differences exist, but they take careful observation to distinguish. Whiskered Screech-Owls are smaller. They are over an inch shorter and weigh 40% less. They have smaller feet and a pale bill compared to the dark bill of the Western. A good field mark I’ve noticed is the weak crossbarring of the Western. The dark lines on its breast run vertically. Whiskered Screech-Owls have bolder cross-barring giving them a more spotted appearance.
Next let’s move on to vocalizations. The two owls sound quite different and listening to a tape recording of their calls is your best bet in learning to recognize them. Owls respond well to these recordings, and many of them are difficult to find without their use, though many owls start hooting as soon as darkness has fallen.
I guess a note on the ethics of using tape recorders is in order. I’ve heard many opinions on the sensitivity of birds to hearing recordings of their calls. I’ll just say that moderation is always in order. When the young have hatched, the parents are on a tight time-energy budget providing for them and themselves, so extra consideration is in order (peak times: June – Whiskered; May – Western).
Each of our two owls has two regularly heard vocalizations. The Western’s classic call is the “bouncing ball” call, a series of 9-15 short whistled hoots that speed up towards the end. And there is the double trill – a short trill immediately followed by a longer one. The classic Whiskered’s song is a series of 5-7 notes all on the same pitch except for the last one or two notes, which are slightly lower. Less common is the “Morse Code” vocalization, that when heard prompts one to say “Hey! There’s the Morse Code call!” It’s a good description of the impression one gets upon hearing it.
One of the great things that birding treats us to every once in a while is to see an owl day-roosting in a tree. It feels sort of like cheating to get to see an owl perched still in bright light, where all the field marks can be studied. On a recent event in Brown Canyon, the Audubon Board and staff were treated to an owl at eye level quietly sitting in a tree trunk notch. It opened one eye, judged us not a threat, and went back into snooze mode. We all got good looks, then got out the books to determine which of these two species it was. I hope fate smiles on you, and treats you to an owl soon. Good luck!
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This page was updated on 02/21/06