SAM D. FITTON, Wyoming Game and Fish Department, Lander, Wyoming 82520 (presentaddress: 113 Lucchesi,Arcata, California95521) OLIVER K. SCOTT, 5120 Alcova Route, Box 16, Casper, Wyoming 82604
The avifauna associatedwith Wyoming's juniper plant community has largelybeen ignored.The purposeof thispaper is to communicateinforma- tion regarding 10 speciesof birds virtually confined, during the breeding season, to the Utah Juniper (Juniperus osteosperraa) community in Wyoming. Since 1979 we have made over 60 tripsto juniper standsstatewide. Most of our field work was conductedin 1982 in southernSweetwater County of southwesternWyoming. Few or no juniper-dependentbirds were found on our visitsto other portionsof the state. Equal time was spentin the extensive standsof the Little Firehole Canyon area 13 km southeastof Green River and along the east-westridge called Powder Rim 100 km southwestof Rawlins.Our objectivesat eachjuniper standwere to documentthe presence and when possiblethe nestingof certainindicative species. The pinyon-junipercommunity of Utah and Coloradobecomes the Utah Juniper communityin Wyoming. Pinyon Pine (Pinus edulis) is very rare along the Utah-Wyomingborder near Flaming Gorge Reservoirand absent elsewherein the state. Nearly homogenousstands of Utah Juniper can be found widely scatteredthroughout the state but are most extensivein the southwesternquarter (Figure1). The other speciesof erectjuniper in Wyo- ming, the Rocky Mountain Juniper (Juniperuss½opulorura), is found most often in associationwith PonderosaPine (Pinusponderosa) or Limber Pine (Pinus flexiIls) and less frequently in association with Utah Juniper. Therefore, it is not a criticalcomponent of the juniper birds'habitat. Wyo- ming'sjuniper-dependent birds occupy habitats in Colorado (Kingeryand Graul 1978) and Utah (Behle 1981) that are not found in Wyoming. The pinyon-junipercommunity is the only habitatsimilar. The 10 speciesof birdsthat we found confinedto the Utah Juniperhabitat in Wyomingare Gray Flycatcher,Ash-throated Flycatcher, Scrub Jay, Plain Titmouse, Bushtit, Bewick'sWren, Blue-gray Gnatcatcher,Gray Vireo, Black-throated Gray Warbler and Scott's Oriole. Their distributionsare shownin Figure 1. The Gray Vireo is reportedin Wyoming for the firsttime. The ScrubJay, Bushtitand Black-throatedGray Warbler are documentedas nestingspecies for the firsttime in the state.The rangesof the remainingsix speciesare expanded considerablyfrom those depicted in the last treatment of the state's avifauna (Oakleaf et al. 1982).
GRAY FLYCATCHER, Empidonaxwrightii. The Gray Flycatcheris an abundant summerresident of the Utah Juniper communityin southwesternand south-central Wyomingaad occupiesmost conditions of canopycover wherevermature trees are found(F!gure 1). The 10 neststhat we observedwere built 1.0 to 2.4 m abovethe groundclose to the trunk or substantiallateral branch of a juniper.The nestinforma- tion for 1982 is as follows:four nestswith three youngeach, 25, 26 and 27 June at FireholeCanyon; five nestswith threeyoung each and one nestwith four young,28
Western Birds 15: 85-90, 1984 85 JUNIPER BIRDS and 29 June at Powder Rim. The nestswere made of looselyentwined juniper bark strips and lined with fine grassblades, feathers and hair. In 1982 nests were most easilyfound duringthe lastweek of June when the adultswere feedingthe nestlings. Confusionin the nomenclatureled some Wyomingornithologists to assignthe wrongname to the DuskyFlycatcher (formerly E. wrightii,now E. oberholseri).Any referenceto "Wright'sFlycatcher" in Wyoming'sliterature refers to the DuskyFly- catcher,not the Gray Flycatcher.
ASH-THROATED FLYCATCHER, Myiarchuscinerascens. This speciesis an uncom- mon summer residentof southwesternand south-centralportions of the state and is rarelyseen elsewhere (Figure 1). The speciesis found mostcommonly among the old gnarledjunipers growing on steep hogbacksor in low areas of severe erosion. We observedthe Ash-throatedFlycatcher using the tips of dead snagsas perchesfrom whichto look out for flyinginsects. The two nestsfound nearthe LittleFirehole Can- yon were lessthan 1.8 m abovethe groundin the naturalcavities of Utah Junipers. Two'pairsof territorialadults were observeddefending the above mentionedcavities, 27 June 1982.
SCRUB JAY, Aphelocoma coerulescens.The ScrubJay is an uncommonpermanent residentof southwesternand south-centralWyoming (Figure1). This jay prefersdry rockyslopes or ravinescovered with sparseto mediumtree cover. Mostforaging takes placeon the groundand in MountainMahogany (Cercocarpus montanus), sagebrush (Artemisiaspp.) and the lower branchesof junipers.We usuallyobserved the species shyly swoopingand glidingamong the junipersand rocksmaking it one of the com- munity'smore elusivespecies. On 30 May 1982 we found a nest containingfour fledglingsat PowderRim. The nest, 1.5 m abovethe ground,was constructed of large juniper and sagebrushtwigs and lined with grass.The breedingrecord for latfiong27 in the WyomingArian Atlas (Oakleaf et al. 1982) is erroneousbecause the observer was actuallyin ColoradoSprings, Colorado (Holden 1872).
PLAIN TITMOUSE, Parusinornatus. A commonpermanent resident of southwestern and south-centralWyoming, the Plain Titmouse is found in most situationswhere matureUtah Junipersgrow (Figure1). It is restrictedto standsof junipersold enough to have naturalcavities or largeenough to attractwoodpeckers. Both typesof cavity nestwere found from 1.0 to 3.6 m abovethe ground. One nestwas found in Little FireholeCanyon, 17 May 1982, withan undeterminednumber of youngheard calling from within;and anothernest, also with an unknownnumber of young,was found 29 May 1982 at PowderRim. Smallfamily groups of up to sixindividuals were oftenseen after fledging.The speciesforages among the thicker lateral branchesof junipers, smallerdeciduous shrubs and sagebrush.
BUSHTIT, Psaltriparusrainlinus. The Bushtitis an uncommonresident of southwesternand south-centralWyoming (Figure 1). It isfound at the edgesof juniper standsforaging in MountainMahogany, sagebrush and the lowerbranches of junipers. The species'distribution seems to be localwithin the Utah Juniperhabitat. For exam- ple, in Little Firehole Canyon 29 km southwestof Rock Springswe found four breedingpairs, at leastthree of whichhad successfullyreared young by 25 June 1982, in an area of lessthan 1 km2. We did not seethe specieselsewhere in spiteof intensive search.The nestingphenology of one of the above mentionedbreeding pairs was followed. We found the nest under construction17 May 1982, full of an undeter- mined numberof chirpingjuveniles 25 June, and empty 26 July. This nest (a long pendantintricate affair of juniperscales, fine grasses,seed hulls,and flowersinter- woven with spider webbing) was collected 9 October 1982 and is now in the ZoologicalMuseum at the Universityof Wyoming.
86 JUNIPER BIRDS
--• PARKLB'G HOR• HERIOA N CAMPBELL ]CROOK - ._J• "L, ß I JOHNSON TETON• •ASHKIE I WESTON
ß •' NIOBRARA FREMONT NATRONA CONVERSE
LINCOLN PLATTE.•OSHEN
F • SWEETWATERCARBON
K LARAM I E
Stands where Jumper dependent birds were found. Species '•3rayFlycatcher Ash-throated Flycatcher Scrub Jay Plain Titmouse Bushtit Bewick's Wren Blue-gray Gnatcatcher Gray Vireo Black-throatedGray Warbler Scott's Oriole •1• UtahJuniper Stands Allunlettered stands were visited * Nest or dependent young found but no Jumper b,rds were found ,/ Nest behavior observed - Observed X No data available
Figure1. Birddistribution in Wyoming'sUtah Juniperstands.
87 JUNIPER BIRDS
BEWlCK'S WREN, Thryornanesbewickii. This wren is probably the most common juniper-dependentbird (Figure1). During yearswith mild wintersa few individuals may remain year-round. Bewick'sWrens are found in most conditionsof juniper size and canopycover so long as naturalor excavatedcavities are present.The eightcavity nestswe observedwere at heightsvarying from 15.0 cm to 9.1 m abovethe ground. We found five nestscontaining an undeterminednumber of young, 28 and 29 June 1982 at Powder Rim, and three nestsalso containing an unknown numberof young, 26 and 27 June 1982 at Firehole Canyon. But adults feeding up to four fledglings were commonlyobserved after thesedates. Although juniper is the mostcommonly usednest substrate in Wyoming, the firstdocumented nest was found in a cottonwood tree (Populussp.) along the Green River (White and Behle 1960). This wren forages on the ground,in shrubs,and in branchletsand foliageof junipers.Even in the heatof the day we observedthe Bewick'sWren singingfrom the tops of juniper trees. In- trudersare harassedby loud scoldinguntil they are out of the firstwren's territory and into the next where the defensebegins anew.
BLUE-GRAY GNATCATCHER, Polioptila caerulea. This fairly common summer residentcan be found nestingin severalwidely scattered juniper stands in the stateand is currently the most widespreadof the juniper-dependentspecies (Figure 1). it is probablymost common in the extremesouthwest, less so in the Casperarea, and least commonon the north slopeof the Owl Creek Mountains.This speciesfrequents areas where deciduousshrubs, sagebrush and junipersgrow in closeproximity. One nest wasfound near Powder Rim, 28 June 1982, containingthree ready-to-fledgeyoung. Blue-grayGnatcatchers forage on the tips of branchesof all availablewoody plants from ground level to the highesttrees.
GRAY VIREO, Vireovicinior. This is the firstreport of the GrayVireo for Wyoming.We came into contactwith three or four differentindividuals in the junipers13 km southeast of GreenRiver from 26 June to 27 July 1982 (Figure1). We mustconsider it a raresum- mer residentuntil additional information can be gathered.More investigationmay docu- mentnesting; a singingmale was followed 26 June 1982 untilit droppedfrom cover and brieflybut loudlyscolded us. The birdswere found in areasof moderatejuniper canopy covergenerously interspersed with MountainMahogany. We observedthat thisspecies usesits gray background-matchingcolor, slow movementsand quietdisposition to re- main unnoticedwhile beingonly a tree or two away from the would-beobserver.
BLACK-THROATED GRAY WARBLER, Dendroica nigrescen$.This speciesis a commonsummer resident of the Utah Junipercommunity. It and the Blue-grayGnat- catcherare the only juniper-dependentspecies regularly found northeastof the con- tinental divide. This warbler is most common in the Casper area, less common southwestof Rock Springsand leastcommon at Powder Rim (Figure 1). It frequents maturestands with a relativelyhigh degreeof canopyclosure. These standsare found usuallyin protectedand gentlysloping areas where moistureis more readily available to plants. In 1982 we observedfour nestsat Little FireholeCanyon from 1.2 to 2.4 na above the ground in junipers;three nestswith four young each and one nestwith one young Brown-headed Cowbird (Molothrusater), 16 and 17 May. The nestswere made of fine stripsof juniper bark and lined with fine grassblades, feathers and hair. Foragingtook place mostlyin junipersand to a lesserdegree in deciduousshrubs and sagebrush.
SCOTT'S ORIOLE, lcterusparisorurn. This species appears to be a rare summerresi- dent. Recent recordsfor this speciesin Wyoming, includingthe first nestingrecord, have been summarizedby Findholt and Fitton (1983). An additionalrecord not treatedin the abovementioned summary needs clarification. In 1930 Kemsiesadded
88 JUNIPER BIRDS this speciesto the list of Wyoming'sbirds as hypothetical.The record was based on what he referredto as "a perfectdescription of the Scott'sOriole" which had beensent to him by Park Ranger Albert Bicknell. The ranger apparentlyhad ample time to observethe birdssince they reportedlynested near the BechlerRiver DistrictRanger Station in Yellowstone National Park. With that area's lush meadows and tall dense standsof LodgepolePine (Pinuscontorta), a more atypicalsetting for a nestingpair of this speciescan hardly be imagined when compared to the habitat in which recent observations have been made. All writerssubsequent to Kemsieshave either decidedto ignorethis record or were unaware of it. Kemsies' businessdocuments, stored in the Cincinnati Museum of Natural History, are so unorganizedthat even if Bicknell'sdescriptive letter was re- tained, it would be impossibleto find accordingto Arthur Wiseman, the museum's curatorof ornithology(pers. comm. 1982). Voucher specimensare no longerneeded for a speciesto be included on the Wyoming list of avifauna, and the hypothetical designationis reservedfor speciesfor which some questionexists concerning details given in the written documentation.Since Bicknell'sdescription cannot be obtained, we believethis recordcan be put to rest after 50 yearsof uncertainty.
Two additionalspecies that we usuallyfound in junipersare not necessarily juniper-dependent.The PinyonJay (Gyrnnorhinu$cyanocephalu$) is found essentiallyin pinyon-juniper habitat in Colorado (Bailey and Niedrach 1965), Utah (Behle 1981) and Idaho (Burleigh1972). In Wyoming, the Pin- yon Jay exhibits more flexibility in its habitat requirements;it is found whereverthere are extensivejuniper stands,but alsoin areasof Limber Pine and PonderosaPine. The only part of the state that lacks this bird is the northwestmountain region. In contrast,the House Finch (Carpoctacu$mex- icanus) is found in a wide variety of low elevation habitatsin Colorado (Baileyand Niedrach 1965), Utah (Behle 1981) and Idaho (Burleigh1972), but in Wyoming thisspecies is restrictedto juniper standsin the southernpart of the state or to habitatsadjacent to human dwellingsthroughout the state. Becauseof itsclose association with man, in additionto its use of the juniper habitat, we do not considerit juniper-dependent.
ACKNOWLEDGMENTS We gratefully acknowledgethe use of Bureau of Land Management, RawlinsDisti'ict, vehicles during 1981. Mostof the field work wasconducted under the auspicesof the Wyoming Game and Fish Departmentin 1982. Bob Oakleaf greatlyencouraged this studyand provided invaluableadvice and discussion.We thank Fred Broermanfor help with the 1981 field work and Terri Fitton for help with the 1982 field work and editorial assistance. LaurenceC. Binford and Dominique G. Hornbergerprovided helpfulcom- ments on an earlier draft of this manuscript.
LITERATURE CITED
Bailey, A.M. & R.J. Niedrach. 1965. Birds of Colorado. Denver Mus. Nat. Hist.. Denver. Behle. W.H. 1981. The birds of northeastern Utah. Utah Mus. Nat. Hist. Occas. Publ. No. 2, Univ. Utah, Salt Lake City.
89 JUNIPER BIRDS
Burleigh,T.D. 1972. Birds of Idaho. Caxton PrintersLtd., Caldwell, Idaho. Findholt,S.L. & S.D. Fitton. 1983. Recordsof Scott'sOriole from Wyoming.West. Birds 14:109-110. Holden, C.H. 1872. Notes on the birdsof Wyoming and Colorado territories.Proc. Boston $oc. Nat. Hist. 15:193-210. Kemsies, E. 1930. Birds of the Yellowstone National Park, with some recent addi- tions. Wilson Bull. 42' 198-210. Kingery, H.E. & W.D. Graul. 1978. Colorado bird distributionlatilong study. Colorado Div. Wildl., Denver. 58 pp. Oakleaf, B., H. Downing, B. Raynes& O.K. Scott. 1982. Wyomingavian atlas. Wyoming Game and Fish Dep., Cheyenne. 87 pp. White, C.M. & W.H. Behle. 1960. Birds of Flaming Gorge reservoirbasin. Pp. 185-208 in Ecologicalstudies of the floraand faunaof FlamingGorge reser- voirbasin, Utah and Wyoming.Univ. Utah Dep. Anthropology,Anthropological Paper No. 48., Salt Lake City. Accepted 2 November 1983
Scott'sOriole. Ash-throatedFlycatcher, Gray Vireo, Black-throatedGray Warblerand Blue-gray Gnatcatcher. Sketch by Keith Hansen
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