Comments on the Status and Distribution of Western and Mountain Bluebirds in Washington

COMMENTS ON THE STATUS AND DISTRIBUTION OF WESTERN AND MOUNTAIN BLUEBIRDS IN WASHINGTON

CHRISTOPHER J. HERLUGSON, Departmentof Zoology,Washington State Uni- versity,Pullman, Washington 99164

Concernhas been expressed for many yearsover the decreasein numbers of both Western Bluebirds (Sialia mexicana) and Mountain Blue- birds(S. currucoides)in Washington.One major problem in attempting to documentthis reporteddecline is the lack of comprehensivestatus and distributiondata. Seasonalreports in AmericanBirds provide sum- mariesof observationsbut often theseare not quantitativein nature. Recent breedingbird surveysconducted by the U.S. Fishand Wildlife Service(Robbins and Van Velzen 1969, Van Velzen and Robbins 1971) are quantitativebut often provideonly limited data on bluebirds.The purposeof this study is to supplyquantitative information on the status and distributionof both bluebirdspecies in Washingtonfor the summer of 1974, to providean analysisof BreedingBird Survey(BBS) data for 1968 through1976, and to evaluatepopulation trends during the past 80 years.

MATERIALS AND METHODS I conductedtimed censuses throughout the statein areasthat seemed to satisfybasic habitat requirements(elevated perches, open spaces, somecover, one or more nestcavities) of bluebirds.Each census, begun at timeswhen bluebirdactivity was considered to be greatest,consisted of a 1 to 3 hourwalk throughan area.During the nestingperiod (see be- low) bluebirdswere active throughout the day,whereas after the young hadfledged, maximum activity occurred in earlymorning and late eve- ning. The walk was usuallyin a circularpattern covering 1 to 5 km. After the initial census,a I to 2 hour search for nests was conducted. Four of the five areaswith active nestswere censuseda secondtime, approximately3 weekslater, to checkthe accuracyof the censusmeth- od andto obtaindata concerning reproductive success. To gain perspectiveon the historical statusand distribution of West- ern and Mountainbluebirds, species lists, surveys, and museumcollec- tions made between 1894 and 1966 were examined. For purposesof comparison,Washington was dividedinto western and easternsections with the crestof the CascadeRange serving as the dividingline. The breedingseason, based on Jewett et al. (1953) and Western Birds 9:21-32, 1978 21 BLUEBIRDS IN WASHINGTON personalobservations, was defined as follows: Western Bluebird, 5 April to 12 Augustand MountainBluebird, 28 April to 25 July. Forty-nine questionnaires,requesting current informationon numbers,species, and habitat of bluebirds,were mailed in 1974 to persons activelyengaged in field work or with accessto areaswhich may have been suitable for bluebirds. Those contacted included U.S. Forest Ser- vicedistrict rangers, National Park Servicebiologists, Fish andWildlife Servicerefuge personnel, Indian Agency superintendents, and managers of state wildlife recreationareas. Thirty individuals(13 west and 17 eastof the CascadeRange) completed the questionnaires. An analysis,based on the methodof Neu et al. (1974), of life zone and habitat utilization was made. Confidenceintervals were placedon the proportionof eachbluebird species observed in a life zoneor habitat type, then comparedwith expectedvalues. The expectednumber of bluebirdswas taken to be the proportionof the total censustime that wasspent in eacharea multiplied by the total numberof bluebirds observedon all areas. The 0.05 levelof significancewas used. For this analysis,both bluebirdspecies were assumedto haveequal accessibility to all areas. From 10 June to 28 August1974, 48 full-time dayswere spentin the field. Seventeenpart-time days were spent in the field from 14 Feb- ruary to 23 May 1974.

RESULTS AND DISCUSSION

Former Status and Distribution Early publishedreports by Dawson(1909), Taylor and Shaw(1927), Burleigh(1930), Kitchin (1930) and Miller et al. (1935) indicatedthat WesternBluebirds were most often observedwest of the CascadeRange. Later reportslisted this speciesas rare (Pearse1946) or asa migrantand winter visitor only (Wick 1958) in extreme northwesternWashington. In easternWashington, Edson (1932), Wing (1944), and others noted isolatedsightings. King (1953) and Hudsonand Yocom (1954) classed Western Bluebirds as rare summerresidents in southeasternWashington. Jewett et al. (1953:523) stated that this species"while not abundant anywhere,enjoys a wide distributionin the state." For the MountainBluebird in westernWashington, the only published observationsduring the breedingseason are from WhatcornCounty (Ed- son 1926) and from Mount Rainier National Park (Dawson 1909, Schef~ fer 1934, Kitchin 1939). All other reportsfrom this part of the state come from migratoryperiods (Jewett et al. 1953). Recordsfrom east~ ern Washingtonare more abundant and many observersreported the bird as common (Dice 1918, Hurley 1921, Larrison1943, Burdick 1944, Yocom 1945, Jewett et al. 1953, King 1953, Hudsonand Yocom 1954). 22 BLUEBIRDS IN WASHINGTON

Figures1 and 2 showlocations for museumspecimens collected during the breedingseason for WesternBluebirds between 1894 and 1960 and for Mountain Bluebirds between 1897 and 1966. Before 1947, West- ern Bluebirdswere taken primarily in westernWashington (65%), whereas after 1948, 62% of the birds were collected east of the Cascades. For the entire period, 75% of the Mountain Bluebirdswere from eastern Washington. Although the number of birds taken in a givenarea is a reflectionof collectingeffort, an important trend in the number of WesternBlue- birds in westernWashington is suggestedby a decreasein specimens. Coupled with a decreaseof publishedobservations, fewer museumspecimens seem to point to a declinein the breedingpopulation of Western Bluebird,swest of the Cascades.No importantchanges have been noted for Western Bluebirds east of the mountains, or for Mountain Bluebirds throughout the state. The distributionof both bluebirdspecies, based on life zone or habitat use, has been describedby many authors. Jewett et al. (1953) reported that WesternBluebirds were found most commonly in the Upper Sonoran and Transition zones, whereas Mountain Bluebirds were found from the Transition to Hudsonian Zone. Dice (1918) recorded Western Bluebirdsas migrantsin bunchgrassand in cottonwood-willowhabitat and as summer residentsin yellow pine habitat, in southeasternWash- ington. He recordedMountain Bluebirdsas summerresidents in bunch- grass,cottonwood-willow, yellow pine and alpine-firhabitats. Observa- tionsby Dumas(1950) closelyparalleled those of Dice for both species.

Present Status and Distribution Seventy-nineWestern Bluebirds were seenduring timed censuses.Sev- en censuses conducted between 0600 and 1200 resulted in 49 bird observations. Six censuses conducted between 1200 and 2000 resulted in 30 sightings. Thirty-nine and 40 Western Bluebirdswere counted in June and July, respectively.None were seenduring timed censusesin August. Sevensightings made while travelingbetween census areas were recordedbut not includedin field censuscounts. Flocks,numbering between6 and 20, were observedon threeoccasions during censuses, but in no instancewere more than 5 adultsseen at any location. Al- thoughnearly 16% of my fieldtime was spent west of theCascade Range, no WesternBluebirds were seenthere (Appendix A). Thirty-oneMountain Bluebirds were seen during timed censuses (Ap- pendix A). Two censuses,conducted between 0600 and 1200, resulted in 6 sightings.Four censusesbetween 1200 and 2000 had a total count of 25. Nineteen, 10, and 2 Mountain Bluebi.rdswere countedin June, July and August,respectively. Three additionalsightings were made 23 BLUEBIRDS IN WASHINGTON

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Figure1. Breedingseason locations in Washingtonfor WesternBluebird museum specimens1894 to 1947(¸), 1948to 1960(0), andpersonal observations and questionnairereports, summer 1974 (ß).

Figure2. Breedingseason locations in Washingtonfor MountainBluebird museumspecimens 1897 to 1947(/X), 1948to 1966(A), andpersonal observations and questionnairereports, summer 1974 ( ß ). 24 BLUEBIRDS IN WASHINGTON whiletraveling between census areas. The only birdsseen on the west sideof the CascadeRange during timed censuseswere 2 at Sunrisein Mount Rainier National Park. All sightingsof WesternBluebirds reported on questionnaireswere from easternWashington, except one recordfrom the Olympic Penin- sula listing this speciesas migratory only. Mountain Bluebirdswere reported in 6 areaswest and in 16 areaseast of the CascadeRange. Five of these (Mitchell Creek, Chelan County; Gold Ridge, ChelanCounty; Lake Quinault, JeffersonCounty; White River, PierceCounty; Rimrock Lake, Yakima County) were sightings,ranging from I to 12 birds,made duringthe breedingseason. Additionally, T. Wahl (pers.comm.) reported Mountain Bluebirdsin June on HurricaneRidge in Olympic National Park, ClallamCounty, and in westernWhatcorn County. The remaining 17 observationswere madeduring periods when juvenile bluebirds form largeflocks and movewidely prior to migration(Power 1966). Table I summarizes results of timed censuses I conducted in areas correspondingto the four life zones, and presentsan analysisof life zone useby bluebirds. WesternBluebirds seemed to useTransition pref- erentially to all other zones, whereasMountain Bluebirdsused Transi- tion, Canadianand HudsonJanas expected. Neither specieswas seenin Upper Sonoranareas during the breedingseason, probably because of the absenceof suitablenesting sites. Although bluebirdswill use nest boxesplaced in Upper Sonoran,they generallyleave the areaand move to Transitionwhen the nestlingsfledge (Power 1966). Six habitat typeswere censusedduring 1974 (Table 2). WesternBlue- birds were seenin edgeand burn areas;Mountain Bluebirdswere seen in burn, farmland and subalpine. All sightingsof WesternBluebirds in edge habitat were from Klickitat County (in the south-centralpart of the state) where the vegetationconsists primarily of CheatgrassBrome (Bromusrectorurn), Oregon White Oak (Quercusgarryana) and Ponder- osa Pine (Pinusponderosa). WesternBluebirds were countedin burns at Turnbull NationalWildlife Refuge,Sherman Pass, Mitchell Creekand Gold Ridge. In theseareas, nest cavitieswere seenin larger(20 cm or greaterdiameter breast height [dbh] )fire-killed treesor stubs.The burn at Gold Ridge consistedof two distinct habitats. Only small(less than 20 cm dbh) treesremained throughout much of the area,probably becauseof post-firetree salvage. All bluebirdswere observednear the edgesof the burn or on steeperslopes where larger stubscontaining cavities were located. Mountain Bluebirds were seen in burns at Sherman Pass and at Mitch- ell Creek, as well as in subalpinemeadow-forest mosaic (Franklin and Dyrness 1973) at Sunrise and at Cutthroat Pass. The observationsin farmland were of a late breedingpair usinga nest box near Bickleton, Klickitat County.

25 BLUEBIRDS IN WASHINGTON

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Bluebirduse of clearcutsfor foraginghas been reportedby Hooven (1969) and Nyquist (1973), but no bluebirdswere seenin the single clearcut(Gifford Pinchot National Forest, Cowlitz County) I censused during the presentstudy. Groundvegetation was widely spacedwithin the clearcut,however no cavitieswere found in the adjacenttimbered areas. R. E. Johnson(pers. comm.) found Westernand Mountainblue- birdsusing clearcuts in Junenear Mount Miseryin GarfieldCounty. No bluebirdswere seenby me in grasslandprobably because of the lack of elevatedperches and nest cavities. The analysisof habitat usein Table 2 indicatesthat both speciesused burns more than expected. This may have been because,in burns, in- sectsseemed plentiful and understoryvegetation was not sufficiently developed(4 to 7 years after the fire) to hinder feedingby bluebirds. The transition area between forest and grassland(edge) probably was usedmore than expectedby WesternBluebirds because of the presence of elevatedperches from which the birdsscanned adjacent grassland and becauseof natural cavitieslocated in many of the older Oregon White Oaks. Mountain Bluebirdswere seenas expectedin both farmland and subalpine. Bluebirdswere seen in a variety of habitat types, all of which are characterizedby widely spacedunderstory vegetation and major tree speciesusually clusteredto form areasof densecover adjacent to, or within, the more open spaces.Power (1966) observedthat open spaces were usedby adultsfor feeding,and that areasof densercover served as protection for newly fledged young. In the absenceof a nest cavity otherwise suitable habitat often remains unused (Hild•n 1965). Census- es conductedduring 1974 supportthis observationin that areasmeeting all the basic habitat requirementsof bluebirds,including seemingly ade- quatefood and cover,were not occupiedwhen nestcavities were absent (e.g., Gold Ridge and Gifford PinchotNational Forest). The distributionof WesternBluebirds described by Jewerret al. (.1953) is probably not entirely accuratetoday. Museumspecimens, published reports and personalobservations indicate little use of Upper Sonoran in Washington.All breedingactivities seem to be restrictedto Transition east of the Cascadeswhere basic habitat requirementsof nest cavities, elevatedperches and fairly sparseground cover are met. Mountain Blue- bird distributionshows little, if any, changefrom that reportedby Jew- ett et al. (1953).

Bluebirdsvs. Starlings One possiblecause for the declinein bluebirdpopulations is nestsite competitionwith Starlings(Sturnus vulgaris) (Rogers 1956). Firstre-

28 BLUEBIRDS IN WASHINGTON

ports of Starlingsin the Northwest were by Mills (1943), Olson (1943) and Wing (1943). Early nestingrecords were reportedby Hudsonand King(1951) and by Braden(1953). Starlingswere classedas a "common winter visitor and rare breeder"in southeasternWashington by Hudson and Yocom (1954:38). Reports of decliningbluebird populationsin northwesternWashington (e.g., Pearse1946) preceededthe establish- ment of Starlingsas breedingbirds eastof the Cascades.Factors other than competition with Starlings,such as increasedurbanization and de- velopmentwest of the Cascades,may havebeen responsible for the early decreaseof WesternBluebird populations in that area. Low population levelscoupled with increasedpressure from Starlingsin later yearscould haveresulted in the apparentexclusion of WesternBluebirds as breeders in westernWashington. Starlings do not occurin the habitatsof either Western or Mountain bluebirds in easternWashington (T. Wahl pers. comm.), which could, in part, explain the apparentstability of those bluebird populations. The most comprehensivecensus data for both bluebirdsand Starlings between 1968 and 1976 is providedby the BreedingBird Survey(BBS). A maximum of 30 censusroutes have been run in Washingtonin any one year. Sixteen routes are east and 14 routes are west of the Cascades. Bluebirdshave been reported on sevendifferent censusroutes, all east of the Cascades. There are no BBS records for bluebirds from western Washington. Starlingshave been reported on 27 censusroutes: 15 east and 12 west of the Cascades.Starlings were countedon everyroute reporting bluebirds. The averagenumber of bluebirdscounted per hour for eachroute reporting that speciesranged from 0 to 2.4 for WesternBluebirds and from 0 to 0.7 for Mountain Bluebirds. Starlingcensus counts were between 5.1 and 27.0 birds per hour. Correlationsbetween the number of WesternBluebirds and Starlingsand betweenMountain Bluebirds•and Starlingswere both negative,but neitherstatistic was significant. The negativecorrelations do howeversuggest a decreasednumber of blue- birdswhere Starlings are present. No consistenttrends were identified for bluebirdnumbers during the 9 year period. The censuscounts for both speciesfluctuated widely from year to year. Starlingnumbers also showed wide fluctuationsand tendedto parallelbluebird numbers, although Starlings were consistent- ly 10 times more abundantthan bluebirds. When Starlingroutes were groupedaccording to whether they were in easternor westernWashing- ton, the sametrends as describedabove were noted. The averagenumber of Starlingsobserved was greater in westernthan in easternWash- ington(41.7 vs. 32.3),but the differencewas not statisticallysignificant.

29 BLUEBIRDS IN WASHINGTON

ACKNOWLEDGMENTS

I would like to thank the members of my thesis committee, R. J. Jonas,R. E. Johnsonand T. S. Russell,for providinghelp and encourage- ment duringthis study. Numerousindividuals contributed many hours of their time observingand recordingbluebird activity or sentme their field notes. Among these, I am particularlyindebted to J. F. Acton, F. H. Anderson, C. Banko, J. R. Bernatz, T. E. Burke, A. Eliason, R. Holtby, B. A. L•usch,B. Moorhead,L. Napier,D. Pridmore,T. H. Rogers, D. Seesholtz,J. W. TerLouw, T. R. Wahl and H. W. Wills. G. D. Alcorn, Universityof PugetSound, and R. E. Johnson,Charles R. ConnerMu- seum,Washington State University,allowed me accessto the collections under their charge. Lists of museumspecimens were obtainedfrom: M. R. Browning,National Museum of NaturalHistory; R. H. Clem,Whit- manCollege; T. Hill, WallaWalla College; and S. Rohwer,Thomas Burke Memorial WashingtonState Museum,University of Washington.R.E. Johnson,J. R. King and G. Murray critically reviewedthe manuscript. This studywas made possible by a grantfrom the Non-GameDivision, WashingtonDepartment of Gameto R. E. Johnson. Additionaltravel fundswere providedby the Graduateand ProfessionalStudents Associ- ation, WashingtonState University. I wouldalso like to thank P. Mattocks,Jr. for supplyingmuch of the BreedingBird Surveydata for Washington.

LITERATURE CITED

Braden,N. 1953. Starlingsnesting in Washington.Murrelet 34:47. Burdick, A.W. 1944. Birds of the northern CascadeMountains of Washington. Condor 46: 238-242. Burleigh,T. D. 1930. Noteson the bird life of northwesternWashington. Auk 47: 48-63. Dawson,W. L. 1909. The birds of Washington. Vol. 1. OccidentalPubl. Co., Seattle. Dice, L.R. 1918. The birdsofWalla Walla and Columbiacounties, southeastern Washington. Auk 35:148-161. Dumas,P. C. 1950. Habitat distributionof breedingbirds in southeasternWash- ington. Condor 52:232-237. Edson,J. M. 1926. MountainBluebird in WhatcomCounty, Washington. Mur- relet 7:41. Edson, J. M. 1932. A reconnaissanceof the sagecountry, easternWashington. Murrelet 13:41-46. Franklin, J. F. and C. T. Dyrness. 1973. Naturalvegetation of Oregonand Wash- ington. USDA For. Serv.Gem Tech. Rept. PNW-8. Hild•n, O. 1965. Habitat selectionin birds. A review. Ann. Zool. Fenn. 2:53-75. Hooven, E. F. 1969. The influenceof forestsuccession on populationsof small animalsin westernOregon. Pages30-34 in H. C. Black,ed. Wildlifeand refor- estationin the PacificNorthwest--A symposium. Sch. Forest., Ore. St. Univ., Corvallis.

30 BLUEBIRDS IN WASHINGTON

Hudson,G. E. and J. R. King. 1951. Nestingof the EuropeanStarling in Adams County, Washington.Murrelet 32:24. Hudson,G. E. and C. F. ¾ocom. 1954. A distributionallist of the birdsof south- easternWashington. Res. StudiesSt. Coil. Wash.22(1): 1-56. Hurley,J. B. 1921. Annotatedlist of YakimaCounty birds. Murrelet2(1): 14.16. Jewett,S. G., W. P. Taylor, W. T. Shawand J. w. Aldrich. 1953. Birdsof Wash- ington State. Univ. Wash.Press, Seattle. King,J. R. 1953. Breedingbirds of the centralPalouse region, southeastern Wash- ington. Unpubl. M. S. Thesis,St. Coil. Wash.,Pullman. Kitchin, E.A. 1930. Fall observationsat Westport. Murrelet 11:71-73. Kitchin, E. A. 1939. A distributionalcheck-list of the birds of Mount Rainier National Park. Murrelet 20:27-37. Larrison,E.J. 1943. An early springreconnaissance of the birdsand mammals of Northrup Canyon,Upper Grand Coulee,Washington. Murrelet 24: 35-46. Miller, R. C., E. D. Lumleyand F. S. Hall. 1935. Birdsof the SanJuan Islands, Washington. Murrelet 16:51-65. Mills, H. B. 1943. Starlingsnesting in Montana. Condor45:197. Neu, C. W., C. R. Byersand J. M. Peek. 1974. A techniquefor analysisof utilization-availabilitydata. J. Wildl. Manage.38:541-545. Nyquist,M. O. 1973. Deer and elk utilizationof successionalforest stages in northernIdaho. U.npubl. Ph.D. Thesis, Wash. St. Univ.,Pullman. Olson, A.C. 1943. Starling in northern Idaho. Condor 45:197. Pearse,T. 1946. Notes on changesin bird populationsin the vicinity of Comox, Vancouver Island-1917 to 1944. Murrelet 27:4-9. Power,H. W., III. 1966. Biologyof the MountainBluebird in Montana. Condor 68:351-371. Robbins, C. S. and W. T. Van Velzen. 1969. The breedingbird survey,1967 and 1968. U.S. Fish Wildl. Serv. Spec.Sci. Rept., Wildl. no. 124. Rogers,T. H. 1956. Nesting season. Palouse-northernRocky Mountain region. Aud. Field Notes 10: 397-399. Scheffer, V. 1934. Notes from Mount Rainier, Washington, 1934. Murrelet 15:81. Taylor, W. P. and W. T. Shaw. 1927. Mammalsand birds of Mount RainierNa- tional Park. USDI Natl. Park Serv. Van Velzen, W. T. and C. S. Robbins. 1971. The breedingbird survey, 1969. U.S. Fish Wildl. Serv. Admin. Rept. Wick, W.Q. 1958. A nine year bird list from Eliza and ProtectionIslands, Wash- ington. Murrelet 39:1-9. Wing, L. 1943. The Starling in easternWashington. Condor 45:159. Wing, L. 1944. Summerbird studiesin the OkanoganCascades. Murrelet 25: 3-8. Yocom, C. F. 1945. Summerbirds in the ColvilleValley and the Selkirk Moun- tains of Washington- 1941. Murrelet 26:19-23.

APPENDIX A. Locationsand resultsof timed censusesconducted in Washington, summer1974. Numbersfollowing each location representthe numberof census hours,the numberof censuses(in parentheses),and the numbersof Westernand Mountainbluebirds, respectively. Abbreviations: SWRA--State Wildlife Recreation Area, NF--National Forest,NP--National Park, NWR--National Wildlife Refuge. EasternWashington Mitchell Creek, Wenatchee NF, Chelan Co. 4.5 (4):26, 15; Sherman Pass, Ferry Co. 2.0 (2):8, 10; Klickitat SWRA, Klickitat Co. 3.5 (3):25, 0; Little PendOreille 31 BLUEBIRDS IN WASHINGTON

SWRA, StevensCo. 5.0 (5):13, 0; TurnbullNWR, SpokaneCo. 4.5 (4):5, 0; Gold Ridge,Wenatchee NF, ChelanCo. 4.0 (3):5, 0; CutthroatCreek, Okanogan NF, OkanoganCo. 5.5 (3):0, 2; 5.0 km S. Bickleton,Klickitat Co. 1.0 (1):0, 2; Han- ford Reservation, Benton Co. 2.0 (2):0, 0. WesternWashington Sunrise,Mount RainierNP, PierceCo. 2.0 (2):0, 2; HurricaneRidge, Olympic NP, Clallam Co. 2.0 (1):0, 0; Gifford Pinchot NF, Cowlitz Co. 1.0 (1):0, 0; Three- leggedBear Avalanche, Rainy Pass,Okanogan NF, OkanoganCo. 1.0 (1):0, 0. Totals, with percentof statewidetotal: EasternWashington-32 census hours (84.2%), 27 censuses,79 WesternBluebirds (100%), 29 MountainBluebirds (93.5%). WesternWashington-6 census hours (15.8%), 5 censuses,0 Western Bluebirds, 2 Mountain Bluebirds (6.5%).

Accepted6 March 1978