J. Raptor Res. 25(4):120-122 ¸ 1991 The Raptor ResearchFoundation, Inc.

DISTRIBUTION OF BOREAL OWL OBSERVATION RECORDS IN

CHRISTOPHER S. GARBER WyomingNatural Diversity Database, The Nature Conservancy, 3765 UniversityStation, Laramie, WY 82077

RICHARD L. WALLEN AND KATHERINE E. DUFFY Grand Teton National Park, P.O. Box 770, Moose, WY 83072

ABSTR^CT.--From1927-89, 50 observationsof Boreal Owls (Aegoliusfunereus) have beendocumented in Wyomingfrom records which include museum specimens, photographs, limited surveys and incidental observations.Observations were primarily in high elevationconiferous forests in the northwesternand southeasternportions of Wyoming.

Distribuci6ndel buho de la especieAegoliusfunereus en Wyoming. Extracto.--Desde 1927 hasta 1989, se han documentadocincuenta observacioneshechas a buhos de la especieAegoliusfunereus en Wyoming. Esta documentaci6n sehizo de registros que incluyen muestras de museo,fotograffas, inspecciones limitadas y observacionesincidentales. Las observacionesfueron pri- mariamentehechas en elevadasforestas de coniferasen las zonasnoroeste y sudestede Wyoming. [Traducci6n de Eudoxio Paredes-Ruiz]

The Boreal Owl (Aegoliusfunereus)was recently Additional observations were obtained from Yellow- confirmedas nestingin the Rocky region stoneNational Park, the Wyoming Departmentof Game and Fish, literature reviews and a review of requeststo of the western United States (Palmer and Ryder 91 museums in the United States and Canada for museum 1984, Ryder et al. 1987). It has been documented specimenrecords. as breedingin statessurrounding Wyoming includ- ing Montana (Holt and Ermatinger 1989), Idaho RESULTS (Hayward and Garton 1983) and Colorado(Palmer We compileda total of 50 observationsfor Wy- and Ryder 1984). Previouslymentioned records from oming from the abovesources from 1927-89. These Wyoming haveincluded 3 observationsreported by 50 recordsrepresent 73 individual owls at 50 sites Palmer and Ryder (1984) and 27 additionalobser- (Fig. 1). Observationsof Boreal Owls in Wyoming vationsreported by Hayward andHayward (in Clark haveprimarily beenin Grand Teton National Park et al. 1989). These authorsprimarily reportedre- (24 records)and in southeasternCarbon County in cordsof incidental observations.In this paper, we the SnowyRange and Sierra Madre Range within present a comprehensivereview of Boreal Owl re- Medicine Bow National Forest (12 records). Ob- cordsin Wyoming which includethe aboverecords, servations were concentrated in these areas since records from preliminary surveys (call-playback), theseare the only areasin Wyoming where prelim- museum specimensand additional incidental obser- inary surveyshave been conducted. vations. Thirty-one (62%) of all of the Wyoming records

METHODS were recordedbetween 1 March through 1 Septem- ber during the probablebreeding season for Boreal Observationrecords for Boreal Owls in Wyoming were compiledand enteredinto The Nature Conservancy'sBi- Owlsin Wyoming.Repeated observations have been ologicaland ConservationDatabase for analysis.Infor- made of Boreal Owls in areas surveyedduring the mation was obtainedfrom preliminary field surveyscon- breedingseason. There is one probablebreeding ductedby R. Wallen andK. Duffy in GrandTeton National recordin the Coon Creek drainageof the Encamp- Park and surveysconducted by stafffrom the U.S. Forest ment River in the Sierra Madre of south- ServiceRocky Mountain Forest and Range Experiment Station in the Medicine Bow National Forest, Carbon centralWyoming. Repeated observations were made County, Wyoming. here of two adultsoccupying a hole in a snagbut

120 WINTER 1991 BOREAL OWL DISTRIBUTION 121

Figure 1. Distributionof BorealOwl recordsin Wyoming.Stippled areas represent the distributionof Subalpine Fir, EngelmannSpruce and LodgepolePine foresttypes after Little (1971). All dotsoutside of stippledarea represent w•nter records.Some dots representmore than one record.

no youngwere confirmed(H. Henry, pers.comm.). In the Rocky Mountain region, Boreal Owl ob- Anotherprobable breeding record is knownfrom the servationshave primarily been in high-elevation vicinity of , Snowy Range mixed coniferousforest. In Colorado, of four pub- Mountainsin south-centralWyoming where an adult lished accounts of Boreal Owl nest sites, two were was observedto bring a vole (Microtussp.) to a in EngelmannSpruce snags, and two were in Lodge- recently fledgedjuvenile (S. Fitton, pers. comm.). pole Pine. Roostsites used by Boreal Owls in Col- Both of these areas are contained within the Med- orado were in Engelmann Spruce, Subalpine Fir icine Bow National Forest. and LodgepolePine (Ryder et al. 1987). In Idaho, In addition,courtship was observedat a potential Hayward (1989) found Boreal Owls primarily in nest cavity locatedin Grand Teton National Park the spruce-firforest zone for nesting,foraging and in 1989, but the adults did not produceany young. roost habitats. Some use has also been observed in Also, juvenile Boreal Owls were photographedin standsof mature Aspens(Populus tremuloides) in- the interior of Grand Teton National Park in 1985. terspersedwith the above coniferousforest types. Consequently,circumstantial evidence indicates that thisspecies breeds in followingareas: Snowy Range/ DISCUSSION Sierra Madre mountains, Grand Teton National From a review of the above literature on Rocky Park, and possiblyin YellowstoneNational Park. Mountain Boreal Owl observationsand the Wyo- The 50 recordsrange in elevationfrom 1770 m ming recordspresented here, it appearsthat habitats to 3240 m with a mean of 2490 m. The 31 Boreal usedby Boreal Owls in the Rocky Mountain region Owl observationsrecorded during the breedingsea- and Wyoming, are primarily subalpine forests of sonranged in elevationfrom 2000 m to 3240 m with Engelmann Spruce, Subalpine Fir, and mature a mean elevation of 2650 m. Habitat recorded for LodgepolePine with someuse of matureAspen stands breedingseason records in Wyoming are comprised which are interspersedwith the above coniferous of high-elevationconiferous forests; dominant tree forest types. speciesinclude Engelmann Spruce (Picea engelman- Consideringthis information, the conifer distri- nzz),Subalpine Fir (Abieslasiocarpa) and Lodgepole bution map for these three tree species,as repre- Pine (Pinus contorta). sentedin Figure 1, probablyroughly representspo- 122 G^RBWRET AL. VOL. 25, NO. 4 tential Boreal Owl habitat within Wyoming. Associationprovided funding for preliminary field re- However,it mustbe emphasizedthat systematicsur- searchand office supportfor this project.The authors would like to thank Gregory Hayward, Evelyn L. Bull, veyshave yet to be conductedin otherforest types, Michael Britten and two anonymousreviewers for com- and that additionalsurveys need to be conducted mentson this report. before any conclusionscan be firmly made about habitat use. Also, the smaller disjunctareas of these LITERATURE CITED foresttypes represented in Figure 1 shouldbe sur- CLARK,Y.W., A.H. HARVEY,R.D. DORN, D.L. GENTER veyed to determineif Boreal Owl distributionis AND C. GROVES[EDS.]. 1989. Rare, sensitiveand contiguousthroughout these habitat typesin Wyo- threatenedspecies of the greateryellowstone ecosystem. ming. Northern RockiesConservation Cooperative, Montana The EngelmannSpruce/Subalpine Fir foresttypes Natural Heritage Program,The Nature Conservancy which are usedby Boreal Owls are the largestand and Mountain West EnvironmentalServices, Jackson, mostvaluable timber resources in Coloradoand Wy- WY. HAYWARD,G.D. ANDE.O. GARTON. 1983. First nesting oming, accountingfor over 90% of the saw-timber record for Boreal Owl in Idaho. Condor 85:501. volume in this area (Alexander et al. 1983, U.S. HAYWARD,G.D. 1989. Habitat use and populationbi- Departmentof Agriculture,Forest Service 1980 in ologyof Boreal Owls in the , USA. Raphael 1987). There is no informationon the ef- Ph.D. thesis,University of Idaho, Moscow, ID. fectsof clear-cutting,habitat fragmentation, and oth- HOLT, D.W. AND D. ERMATINGER. 1989. First con- er forestpractices on BorealOwls in the U.S. Con- firmed nest site of Boreal Owls in Montana. North- sequently,the BorealOwl is listed,or proposedfor western Naturalist 70:27-31. listing, by the U.S. Forest Serviceas a "Sensitive LITTLE, E.L. 1971. Arias of United Statestrees. Vol. 1. species"across its entirerange of distributionin the Conifersand importanthardwoods. Misc. Publication lower 48 states. In addition, the Boreal Owl is also No. 1146, U.S. Departmentof Agriculture,Forest Ser- listed as a speciesof concernby stateNatural Her- vice, Washington, D.C. PALMER,D.A. AND R.A. RYDER. 1984. The first doc- itage or nongameprograms in its entire breeding umentedbreeding record of the Boreal Owl in Colo- seasonrange in the lower 48. Listing by theseagen- rado. Condor 79:215-217. cies reflects both the threat to the above mentioned RAPHAEL,M.G. 1987. The CoonCreek Wildlife Project. habitat and a generallack of information.We hope effectsof water yield augmentationon Wildlife. Pages that the informationpresented in this paperwill be 173-179 in C.A. Troendle, M.R. Kaufman, R.H. usefulto resourcemanagers and serveas an incentive Hamre and R.P. Winokum [LBS.], Management of for further investigations. subalpineforests: building on 50 years of research. General TechnicalReport RM-149. U.S. Department ACKNOWLEDGMENTS of Agriculture,Forest Service,Ft. Collins, CO. The followingindividuals contributed information which RYDER,R.A., D.A. PALMER,AND J.J. RAWINSKI. 1987. made this report possible:Terry McEneaney of Yellow- Distribution and status of the Boreal Owl in Colorado. stone National Park; Hank Henry, Debbie Finch and Pages169-174 in R.W. Nero, R.J. Clark, R.J. Knap- Leslie Watson of the U.S. ForestService-Rocky Mountain ton and R.H. Hamre, [LBS.],Biology and conservation Forest and Range Experiment Station, and Sheri Ritter of the WyomingDepartment of Gameand Fish. Also, the of northernforest owls. General Technical Report RM- LosAngeles County Museum and University of Wyoming 142. U.S. Department of Agriculture,Forest Service, Vertebrate Museums contributedspecimen information. Fort Collins, CO. Finally, the WyomingNature Conservancy,Grand Teton National Park and the Grand Teton Natural History Received8 July 1991; accepted14 August 1991