THE SPOTTED AT ZION NATIONAL PARK,

KENNETH KERTELL, Zion National Park, Springdale, Utah 84767

The first sightingof the ( occidentalis)at Zion National Park was on 9 November 1963 (Wauer and Carter 1965). Al- thougha pair was closelyobserved by Theron Twogoodon 29 August of the following year, there were no more reportsof this uncommon westernowl for severalyears. Then, between1974 and 1976, employ- ees at Zion carefully identified this speciesat six different locations. In 1974 a total of six Spotted was observedat three locations. In 1975 one of the 1974 sites was found inactive but a new one was dis- covered; a total of five owls was at three locations. In 1976 two new locationswere found and, althoughtwo previouslyactive sites were not investigated,five owls were seenat four locations. In light of the scar- city of information on the SpottedOwl in Utah (Behleand Perry 1975), thesesightings are certainly heartening. A brief look at the owl'shabitat in Zion might help explainits abun- dance. All six locationsshow important geologicand climaticsimilari- ties. All sightingshave been in or around very narrow, steep-walled canyons cut out of the Navajo sandstoneformation by intermittent streamsat an elevationof approximately1560 m. Becauseof the highly resistantlower red portion of the Navajo,it is not unusualto find many canyonsat this elevation. Owl canyons1 and 2 are excellent examples of "hanging"canyons, left suspendedabout 270 m above,and on oppo- site sidesof, the floor of Zion Canyon, which is about 1290 m at this point. They are no more than 15 m wide in most placeswith walls risingmostly vertically about 360 m. Both canyonsare about 1.6 km in length. Canyon3 is about11.2 km longand was formed by a major tributary of the Virgin River. It is alsoabout 360 m deep and at the place where the owl was seenis asnarrow as canyons1 and 2. Canyons 4 and 5 are extremelynarrow, cool, vegetation-choked crevices that have eroded along fractures in the sandstoneand run at steep anglesinto canyonsof much largersize. Canyon6 deviatesfrom the usualpattern, being more open and thus warmer than the others. It does,however, have a few cool, vegetatedcrevices near the place wherethe owlswere consistentlyseen. The approximatedistance between each canyon and the nearestother canyonwhere owlswere locatedis asfollows: Canyon 1-canyon 2, 1.6 km; canyon 2-canyon 3, 5.6 km; canyon 2-canyon 4, 7.2 km; canyon 4-canyon 5, 2.4 km; canyon5-canyon 6, 5.6 km. The high elevation and extreme narrownessof these canyons and crevicesresults in summertemperatures perhaps 20øF cooler than one would expect at the bottom of Zion Canyon or on the plateauabove. Outside the visitor center, at the bottom of Zion Canyon, temperatures may be close to 38øC during June, July and Augustwith the plateau Western 8:147-150, 1977 147 SPOTTED OWL AT ZION NATIONAL PARK

only slightlycooler. The comparativecoolness of the canyonsis re- flectedin thegrowth of suchtrees as White Fir (Abiesconcolor), Doug- las Fir (Pseudotsugamenziesii), Bigtooth Maple (Acer grandidentatum) and Boxelder(A. negundo)on their floors. Sixty-fivepercent of our sightingshave been of an owl or owlsperched at middayin thislush canyonbottom vegetation. A few PonderosaPines (Pinus ponderosa), Gambel Oaks ((•uercusgambelii) and Shrub Live Oaks (Q. turbinella) are mixed in, but generallygrow along the moreexposed upper walls and rim, and arecommon on the plateau.The apparentabsence of this owl from the plateauand the bottomof Zion Canyonfurther empha- sizesthe importanceof thesecool canyons.Also, asit hasbeen noted in (Phillips et al. 1964), SpottedOwls appear to be absentfrom most or all areasinhabited by Great-hornedOwls (Bubovirginianus), whichat Zion arecommon everywhere except in thesenarrow canyons. The abundant elevated potholes and crevicesin the walls of these canyonsmay be veryimportant to SpottedOwls as nest sites. Although no nestshave been discovered, there is excellentevidence that the Spot- ted Owl is nestingsuccessfully. In five of the six locationstwo adults, a young or all three have been seenon at least one occasionin the lastthree years. Pairs were noted at canyon1 on 3 July 1975,at canyon 2 on 23 June,13 and 22 Augustand 5 September1976, anda pair with one young was at canyon 6 on 18 July 1974. This young owl was seen againon the night of 22 July. With the aid of flashlightsobservers could seedistinct horizontal barring on the breastand clumpsof downstill in evidencethere and on the belly. The youngowl shriekedcontinually, especiallyin responseto a prey-bearingadult. Two otherwell-developed younghave been reported. One wasperched with a singleadult at can- yon 4 on 9 August1974 and one was perchedalone at canyon3 on 4 September1975. Bothwere identified as young by the remainingtuffs of down. Woodratsmay be an important sourceof food for these owls. The skullsof four woodrats(probably Neotoma lepida) and a pocketgopher (Tbomomyssp.) were found in five pelletscollected under a perchat canyon2 on 23 June 1976. An adult passedto a youngwhat appeared to be a woodraton the night of 22 July 1974 at canyon4. The fledg- ling experiencedcontinued difficulties in trying to swallowthe large rodent. At canyon2 the casingof a rhinocerosbeetle (subfamily Dy- nastinae)was found in a pellet collectedon 3 September1976. The SpottedOwl hasresponded readily upon two occasionsto taped recordingsplayed in springand early summer. In mid-May 1976 Tom Boner of the Utah Division of Wildlife Resources called in and recorded a singleadult at canyon4 by playingSpotted and Barredowl callstaken from Kellogget al. (1962). The secondresponse was on the nightof 23 June1976 whenNancy Sprague, Donna Sakamoto and I enteredcanyon

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2 hopingto verify the presenceof SpottedOwls there. At 2015, while it was still light, we heard the "ho ho-ho hooo" call of a SpottedOwl from somewhereup in the canyon. At 2030 one flew to a perch 3.6 m up in a White Fir about 7.5 m away from us. At 2045 it wasjoined by its mate. They perched together for 15 minutes before moving away in the approachingdarkness. At 2119 I played a short Spotted Owl re- cordingand immediatelyboth birdsflew back and perchedabout 6.5 m aboveus. For 10 minutesthey madean incrediblevariety of calls. They beganwith a seriesof short barks very similar to those of a smalldog, and apparentlydesigned to drive the intruderaway. Occasionallyone

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Spotted Owls (Strix occidentalis). Zion National Park, Utah, 3 July 1975. Photo by K. Kertell 149 SPOTTED OWL AT ZION NATIONAL PARK would issuea seriesof 10-13 hoots changingquality at the end, sound- ing like "hohohohohohohohohohu hu hu," as describedby Burton (1973). After about 7 minutesof this and as the owls beganmoving away, apparently losing interest, they begangiving whistles and a few "ho ho-hohooo" songs. The Spotted Owl appearsto be enjoyingexcellent success at Zion National Park. With the largenumber of relativelyinaccessible canyon sitesmeeting the owl's habitat demandsat Zion, and in the surrounding plateau country, there is every reasonto believe the owl will continue to thrive.

ACKNOWLEDGMENTS

I wish to thank SuperintendentRobert Heyder, BiologistHank Mc- Cutchen and Ranger Peter Scott for encouragementand advice. I am alsograteful to all thoseindividuals who reportedtheir sightings.

LITERATURE CITED

Behle, W. H. and M. L. Perry. 1975. Utah birds. Utah Mus. Nat. Hist., Salt Lake City. Burton, J.A. 1973. Owls of the world. E. P. Dutton & Co., New York. Kellogg, P. P., A. A. Allen, R. T. Petersonand W. W. Gunn. 1962. A field guide to western bird songs(record album, 3 discs). Houghton-Mifflin Co., Boston. Phillips, A., J. Marshall and G. Monson. 1964. The birds of Arizona. Univ. Ari- zona Press, Tucson. Wauer, R. H. and D. L. Carter. 1965. Birds of Zion National Park and vicinity. Zion Nat. Hist. Assoc.,Springdale, Utah.

Accepted31 October 1977

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