Maricopa Audubon Society Birds in Maricopa County
 

Arizona Special Species:
Whiskered Screech-Owl

By Jim Burns

Geography and climate have conspired to give Arizona a plethora of special bird species, species found only here or more easily here than in any other state. The consequent birding buzz has all but drowned out one of Arizona's best kept birding secrets - the diversity of its owls. Thirteen of the nineteen North American owl species can be found in the state and a fourteenth, Boreal Owl, is periodically searched for in pockets of proper habitat which exist in the White Mountains. Of these thirteen, Whiskered Screech-Owl, Elf Owl, and Ferruginous Pygmy-Owl truly qualify as "Arizona special species."

Whiskered Screech-Owl, Otus trichopsis, has been recorded in the extreme southwestern corner of New Mexico, but otherwise in the states is found only in the mountain ranges of southern Arizona, with its range extending southward, on both slopes of Sonora, through Mexico to central Nicaragua.

Whiskered Screech OwlWhiskered Screech Owl
©2000, Jim Burns. All Rights Reserved
Western Screech OwlWestern Screech Owl
©2000, Jim Burns. All Rights Reserved

As recently as the early '80s, birding literature indicated this species withdrew southward from its Arizona breeding territory in the winter, but it is now known to be a permanent resident. Indeed, this past November we had a pair of Whiskereds calling near Patagonia.

Whiskered Screech-Owls in Arizona inhabit pine/oak associations in all the mountain ranges from the Santa Catalinas south, primarily above 5,000 feet, and they are common within this habitat. We saw our life Whiskered in May, 1979 on a Maricopa Audubon Society field trip led by Jim Anderson, then the manager of the Ramsey Canyon Preserve. Jim played a Whiskered tape just inside the national forest boundary of Carr Canyon and the response was immediate. It was Jim's opinion that Whiskereds were so plentiful and so "callible" that discreet use of tapes or voice mimicking would not harm the species.

Although some overlap may occur with its look alike congener, Western Screech-Owl, Whiskereds generally occur at higher elevations and prefer denser woodlands than the latter. Traditionally good places to see Whiskereds have been Bear Canyon picnic area on the road to Mt. Lemmon north of Tucson, the upper parking lot in Madera Canyon in the Santa Ritas, the end of the road in Miller Canyon in the Huachucas, and anywhere along the road above the visitors' center in Cave Creek Canyon in the Chiricahuas.

In Arizona Whiskereds nest in May, typically laying three to four eggs in natural oak or sycamore cavities or abandoned flicker excavations. This species is most vocal from April through June. If you can't seem to be in the right woods on the right night to hear calling Whiskereds and are hesitant to call them up yourself during nesting, you may want to try right now during the winter season. Some feel that Whiskereds, like Western Screech-Owls, come more readily to imitations of their calls when they are sorting out territories and resolving disputes with neighboring and transient birds prior to the actual nesting.

The Whiskered call is a series of soft hoots, long and short notes interspersed, which is often likened to Morse Code, and is quite distinct from the calls of Western Screech-Owl and Flammulated Owl, species which might be found in the same areas. As is often the case with our small owls, it is somewhat ventriloquial and usually closer than it sounds. Although numerous theories, both scientifically sound and apocryphally arcane, have been advanced for best owling in full moonlight, the best reason is apparently the simplestit is easier to see the owl come in on a bright night than in total darkness.

Whiskered Screech-Owls are said to be strictly nocturnal. They do not begin to hunt until after dark, roosting silently during daylight in a cavity or in dense foliage next to a tree bole. This begs two questions. Are they ever seen in daylight and, if so, can they be distinguished from Western Screech-Owl without benefit of vocalization? Despite what the literature implies, affirmative to both. Within the past few years there have been at least two hotline reports of Whiskereds seen fully exposed in tree cavities at eye level during daytime hours. One of these reports came from Stewart campground in Cave Creek and one from the nature trail above Proctor Road in Madera Canyon.

If you're really prepared for that first daytime Whiskered, you'll whip out your micrometer and measure the rictal bristles at the base of its bill. They'll be longer than those on a Western, just another forehead smacking example of a species named for one of its distinguishing yet indistinguishable and laughably irrelevant field marks. But, there are three field marks to look for. Check out the accompanying photos and see if you can discern the differences.

The first and perhaps best field mark is bill color. The tip of the upper mandible on both species will be light, but on a Western Screech-Owl the basal two-thirds is dark whereas the Whiskered's will be greenish-yellow in that area. A second diagnostic is the general pattern of the underparts. Breast and belly feathers of both species are light with a single dark vertical shaft crosshatched by several dark horizontal streaks. On Westerns the crosshatching is closer together and much narrower than that of the Whiskered, giving the latter a bolder, more distinct look than the former's muted, less obvious pattern.

The third field mark brings to light the fascinating interplay between prey species, habitat niche, and structural evolution. Western Screech-Owls live on rodents, but have been known to resort to insects if their preferred prey population is down. Whiskered Screech-Owls live on insects, but have been known to take an occasional rodent if presented with the opportunity. Both capture their prey feet first with their talons. Bet that the Western has proportionately larger feet than the Whiskered. After multiple observations of both the difference will seem obvious, even without side by side comparison.

Despite its specialty status, Whiskered Screech-Owl may well be the most predictable and easiest of Arizona's thirteen owl species to just decide to walk out your door and go see. It's permanent, it's vocal, it's common in the proper habitat, and much of that habitat includes delightful-even-in-winter camping and hiking venues in southern Arizona's accessible national forests. Would you rather be scanning for Snowy Owls on the harbor ice in Duluth this time of year?

 
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Copyright © 2012 Maricopa Audubon. All Rights Reserved
Last updated: June 15, 2012 11:43