UPDATED GEOGRAPHIC DISTRIBUTION OF EIGHT IN CENTRAL ALASKA

ANNA-MARIE BENSON and THOMAS H. POGSON, Alaska Observatory, P.O. Box 80505, Fairbanks,Alaska 99708 (currentaddress of PogsonAlaska Canoe Base, P.O. Box 3547, Homer, Alaska 99603) TERRY J. DOYLE, Tefiin NationalWildlife Refuge, P.O. Box 779, Tok, Alaska 99780 (current addressTen ThousandIslands National Wildlife Refuge, 3860 TollgateBlvd., Suite 300, Naples,Florida 34114)

ABSTRACT: We documentedthe occurrenceof eight rare passerinesin central Alaska.Our observationsof the Yellow-belliedFlycatcher, Red-breasted Nuthatch, Arctic Warbler,Golden-crowned Kinglet, Tennessee Warbler, Palm Warbler,Mourn- ing Warbler,and Clay-coloredSparrow, provided new distributionalinformation on the occurrenceof these speciesin centralAlaska. Mist nettingwas essentialto documentingthe geographicdistribution of thesespecies because mist-net captures representedthe only occurrenceof severalspecies. Additionally, many of these recordscould not havebeen identified to subspecieswithout collecting individuals as voucherspecimens that couldbe verifiedby other scientists.

We usedstandardized mist-netting protocols to conductintensive studies of the migration,population dynamics, and life historiesof passerinebirds in the TananaRiver valley of centralAlaska from 1992 to 1998. Duringthese studies,we documentedthe occurrenceof eight rare species.Here, we reportcaptures and associated observations of thesespecies that update our current understandingof the geographicdistribution of these speciesin central Alaska.

STUDY AREA

The TananaRiver valley is locatedin centralAlaska and isbordered to the southby the AlaskaRange and to the northby the Yukon-TananaUplands, an east/westhighland of maturerounded hills (Figure 1). The Tananavalley is a well-documentedmigration corridor for manyspecies of birdsincluding SandhillCranes (Grus canadensis)(Kessel 1984), many speciesof water- fowl, shorebirds, (Cooper and Ritchie1995), and raptors(Coo- per and Ritchie1995, Mcintyreand Ambrose1999). Fairbanksis located near the confluence of the Chena and Tanana rivers at 130 m elevation. Tok and ScottieCreek are locatedin the Upper Tanana Valley (Figure 1) at elevationsof 500 and 550 m, respectively. The Fairbanksmist-netting station covered approximately20 ha at Creamer'sField Migratory Waterfowl Refuge in Fairbanks(64 ø 50' N, 147 ø 50' W). A seasonallyflooded wetland and a largeagricultural field bordered the mist-nettingstation. The dominanttree speciesin the studysite were Paper (Betula papyrifera) White Spruce (Picea glauca), Balsam Poplar (Populus balsarnifera),Trembling Aspen (Populus trernuloides), and willow (Salix spp.). The Tok migrationstation was located 11 km west of Tok (63 ø 22' N, 143ø 12'W) and 280 km SE of Fairbanksin a 65-ha patch of early

100 Western Birds31:100-105, 2000 PASSERINES IN CENTRAL ALASKA

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successionaldeciduous forest on a hillsidesurrounded by closedforest of Black(Picea mariana) and White spruce. The ScottieCreek mist-netting site was a stationfor monitoringavian productivityand survivorship(M.A.P.S.; DeSanteet al. 1993) established alongthe ChisanaRiver at the mouthof ScottieCreek (62 ø 41' N, 141ø 16' W), nearthe Canadianborder approximately 125 km SE of Tok. This site was locatedin a 400-ha standof closedBalsam Poplar forestwith an understowof openmedium and tall willowand alder (Alnus crispa).

METHODS

At Fairbankswe conductedstandardized mist netting from 1992 to 1998 usingarrays of 22 to 50 standard(30 mm mesh,2.6 m x 12 m) mistnets. Duringspring migration (25 April-15 June)we operatednets daily from 06:00 to 13:00. Duringsummer (16 June-14July) we operatednets once duringfive-day sampling periods from 06:00 to 13:00.During fall migration (15 July-30September), nets were opened at sunriseand closed 7 hourslater. The Tok migrationstation consisted of up to 21 standardnets operated dailyfor 6 hoursbeginning at sunrise,from late April to earlyJune during springmigration 1994-1998 andfrom late July to earlyOctober during fall migration 1993-1998.

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The ScottieCreek M.A.P.S. stationwas operatedonce every 10 days from 10 Juneto 10 August1993-1998 with 11 standardnets used in 1993 and 12 thereafter.The stationwas operated for 6 daysin 1993, 1997, and 1998 and for 7 daysin 1994, 1995, and 1996. The 15 specimenswe collectedare depositedat the Universityof Alaska Museum (UAM), Fairbanks.

RESULTS

We banded51,792 individualsof 65 speciesduring 223,708 net hoursof operationfrom 1992 to 1998 (Table1).

Yellow-belliedFlycatcher (Empidonax flaviven tris) Our dataindicate a recentrange expansion of thisspecies into east-central Alaska,where it isnow knownas a possiblebreeder and rare fall visitant. We nettednine individualsfrom 4 to 27 Augustin fiveof sevenyears. Four were in Fairbanks[20 August1993 (UAM 6373, immaturefemale), 13 August 1997 (UAM 7427, immaturefemale), 15 August1997, 27 August1998], five in Tok [three4-16 August1994 (immaturemale collected8 August 1994, UAM 6579), 23 August1996, 27 August1998]. From 10 to 28 June1992-1998 we recordedtwo to ninesinging males annually, for a total of 18 records,along the Richardson,Taylor, and Alaskahighways. We collectedone adultmale at Mile 43 on the TaylorHighway (63 ø 49' N, 142 ø 12'W). The Yellow-belliedFlycatcher was previously considered a casualsummer visitantin easterncentral Alaska, on the basisof a singlerecord (Kessel and Gibson1978). In BritishColumbia, the northernmostpublished records are southof approximately54 øN, exceptfor onefrom near Fort Nelson in June 1982 and one near Atlin in August1914 (Campbellet al. 1997). Red-breastedNuthatch (Sitta canadensis) Bandingand concurrentincidental observations suggest a recentrange expansionof the Red-breastedNuthatch into the TananaValley. We banded 19 individualsduring three autumns, four in Fairbanksand 15 in Tok. Fifteen werebanded in 1994, one in Fairbankson 23 August,14 in Tok from 11 to 26 August.In 1995, we bandedone in Tok on 27 Augustand one each in Fairbankson 2 Augustand 27 SeptemberAnother bird was banded at

'l¾,l•!e! Numberof BirdsBanded and Net-Hoursof Opera- tion at Tetlin NationalWildlife Refuge and the AlaskaBird Observatory,1992-1998

Spring Summer Fall Total

Individualsbanded 9864 1498 40,430 51,792 Speciesbanded 47 30 58 65 Net-hours 92,310 7249 124,149 223,708

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Fairbankson 11 August1996. Of the 17 individualsthat were aged,three were adults,and of the 16 individualsthat were sexed,eight were male. The irruptionduring 1994 waswidely documented by observations of this speciesbeginning in earlyAugust. Nuthatches were first observed during this time in the Upper TananaValley on 6 August,and they were seenor heard almostdaily thereafter until mid-Septemberat many locations.Numbers decreasedfrom mid-Septemberto mid-October,but birdswere seendaily at severalfeeders in the Tok areauntil the arrivalof severelycold weather (-60 ø F) in earlyDecember, after whichthey were againscarce. In Fairbanks,25 individualswere recorded on the Christmas Bird Count in 1994, five in 1995, three in 1996, nine in 1997, and five in 1998. Additionally,this specieshas bred in the TananaValley since 1994 (B. Kesselpers. comm.). The Red-breastedNuthatch was previouslyconsidered a casualvisitant in autumn in centralAlaska (Kesseland Gibson 1978).

Arctic Warbler (Phylloscopusborealis) The Arctic Warbler is more widely distributedin central Alaska than previouslyknown. We captured20 individualsin five of sevenyears, 15 in Fairbanksand 5 in Tok. All buttwo, on 9 Juneand 19 September,were from 10 to 27 August.The six individualscaptured in 1994 includedtwo on 15 August(UAM 6571) and one eachon 22 Augustand 19 September(UAM 6570) in Fairbanksand one eachon 16 and 22 Augustin Tok. In 1995 we bandedone in Fairbankson 16 August.In 1996 we nettedfour, on 9 June (UAM 6940) and 17 Augustin Fairbanksand on 10 and 21 August(UAM 6992) in Tok. In 1997 we bandedfive in Fairbanks(two on 17 Augustand one eachon 18, 20, and 27 August)and one in Tok (15 August).In 1998, we bandedthree in Fairbanks,on 14, 17, and 18 August.Of these 20 individuals,four were adults,captured 9 June 1996, 10 August 1996, 16 August1994, and 18 August1997. The 9 June 1996 captureis noteworthy as an extremelyearly arrival date in centralAlaska (cf. Patonet al. 1995). Arctic Warblersbreed commonlyin subalpinehabitats in centralAlaska southof the AlaskaRange, primarily west of the RichardsonHighway (D. D. Gibsonpers. comm.). Prior to thisstudy there was only one recordfrom the TananaValley, on 28 August1963 (Whiteand Brooks1964), and none in easterncentral Alaska or adjacentCanada (Godfrey 1986). All our speci- mens are P. b. kennicotti.

Golden-crownedKinglet (Regulus satrapa) Our mist-nettingresults suggest this speciesis a rare fall migrantin the TananaValley. We captured13 individualsfrom 28 Augustto 30 September in five of sevenyears, three in Fairbanksand 10 in Tok. In 1994, two were in Tok (5 and 10 September);in 1995, two in Fairbanks(11 and 25 September)and three in Tok [28 August,14 (UAM 6767) and 25 Septem- ber);in 1996, one in Tok (26 September,UAM 6982); in 1997, one in Tok (30 September,UAM 8835); in 1998, one in Fairbanks(23 September)and threein Tok (8, 9, and25 August).Only two of thesebirds were adults, those capturedon 25 September1995 and 9 September1998. In additionto our bandingresults, a window-killedspecimen was found in Fairbankson 24 September 1997 (UAM 7355).

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The Golden-crownedKinglet was previously considered a casualsummer and fall visitant in central Alaska (Kesseland Gibson 1978). Daniel D. Gibsonof the Universityof AlaskaMuseum has identifiedthese specimens as R. s. amoenus.

TennesseeWarbler (Vermivora peregrina) Our studiessupport this species being a casualsummer and fall visitant to centralAlaska (Kessel and Gibson 1978). We capturedtwo during this study, a first-yearmale on 10 August1992 (UAM 6141) in Fairbanksand an adult male on 30 June 1995 at Scottie Creek. We recorded four additional TennesseeWarblers from centralAlaska in 1995 and 1996: a singingmale and secretive female observed 10-23 June 1995 at Mile 158 of the RichardsonHighway, !a singing male observed on 24 June1995 nearDelta Junction,and a singi.n,gadult male collected (UAM 6955) on 23 June1996 at Mile 87 of the TaylOrHighway (64 ø 07' N, 141 ø33' W). The observations of the secretivefemale suggest this species may alsobreed in centralAlaska. Palm Warbler(Dendroica palmarum) We nettedtwo first-yearbirds in Fairbanks,a maleon 25 September1994 (UAM 6577) and a femaleon 14 September1995 (UAM 6717); addition- ally,immature were netted at Dry Lakein the centralTanana Valley on 11 September 1991 (UAM 5939)and 16 October 1987. We identifiedall of theseindividuals as nominatepalmarum. The Palm Warbleris a recent casual visitant throughoutAlaska; most records are from southeastern Alaska, but there have been recordsas far west as Nunivak Island and as far north as Barrow (Gibsonand Kessel1992).

MourningWarbler (Oporornis philadelphia) We nettedan immaturemale on 9 September1992 in Fairbanks.The first substantiatedrecord of a member of this genus in central Alaska, the specimen(UAM 6143) wasidentified by K. C. Parkesat CarnegieMuseum of NaturalHistory. There is only one previousAlaska record of thisspecies, of a specimencollected 29 September1987 at MiddletonIsland in the Gulf of Alaska(Gibson and Kesse11992).This specieshas recently been found to be common during summer in the La Biche River drainageof extreme southeastYukon Territow (Bowling1995). Clay-coloredSparrow ($piz½lla pallida) The first confirmedcentral Alaska record of this specieswas of an adult malenetted on 31 May 1995 (UAM 6706) in Tok. Priorto thisstudy there were three recordsof the Clay-coloredSparrow in Alaska (Gibsonand Kessel1992). The northernextreme of the documentedbreeding range of this speciesis northeasternBritish Columbia and southwesternNorthwest Territories,Canada (Godfrey 1986).

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ACKNOWLEDGMENTS

We acknowledgethe manypeople who assistedwith the bandingprograms at the AlaskaBird Observatory and Tetlin National Wildlife Refuge, without which the extent of seasonalcoverage would not havebeen possible. We are especiallygrateful to those individualswho took the time to documentspecies of unusualoccurrence: Jeffrey J. Bouton,Cory R. Davis,Todd D. Eskelin,Robert I. Frey, Keith W. Larson,Ryan C. Means,Ramiel K. Papish,Steve K. Springer,Henry K. Timm, LisaA.Webster, and Dawn R. Williams.Nancy D. DeWitt, Daniel D. Gibson,Lori Quakenbush,and TheodorR. Swemreviewed earlier drafts of the manuscript.We are indebtedto Brina Kesseland DanielD. Gibsonof the Universityof AlaskaMuseum for their yearsof compiling,maintaining, and publishingrecords relating to the distributionof Alaska birds.Our work wouldhave sufferedif not for their adviceand assistanceduring the preparationof this manuscriptas well as duringthe courseof our studies.

LITERATURE CITED

Bowling,J. 1995. Summerseason. British Columbia/Yukon region. Natl. Audubon Soc. Field Notes 49:966-970. Campbell,R. W., Dawe, N. K., McTaggart-Cowan,I., Cooper,J. M., Kaiser,G. W., McNall, M. C. E., and Smith, G. E. I. 1997. The Birds of BritishColumbia, vol. 3. Univ. Br. ColumbiaPress, Vancouver. Cooper,B. A., and Ritchie,R. J. 1995. The altitudeof birdmigration in east-central Alaska:A radarand visualstudy. J. FieldOrnithol. 66:590-608. DeSante, D.F., Burton, K. M., and Williams,O. E. 1993. The MonitoringAvian Productivityand Survivorship(MAPS) program,second annual report (1990 to 1991). Bird Populations1:68-97. Gibson, D. D., and Kessel,B. 1992. Seventy-fournew avian taxa documentedin Alaska 1976-1991. Condor 94:454-467. Godfrey,E. W. 1986. The birdsof Canada,rev. ed. Natl. Mus. Nat. Sci., Natl. Mus. Canada, Ottawa. Kessel,B. 1984. Migration of SandhillCranes, Grus canadensis,in east-central Alaska, with routes through Alaska and western Canada. Can. Field-Nat. 98:279-282. Kessel,B., and Gibson,D. D. 1978. Statusand distributionof Alaska birds.Studies Avian Biol. 1 Mcintyre,C. L., and R. E. Ambrose.1999. Raptormigration in autumnthrough the Upper Tanana River Valley,Alaska. W. Birds30:33-38. Paton, P. W. C., Pogson,T. H., and Rexstad,E. 1995. Developmentof landbird- monitoringprotocols for nationalparks in Alaska. Unpublishedreport to the NationalPark Service(order from AlaskaBird Observatory,P.O. Box 80505, Fairbanks,AK 99708). White, C. M., and Brooks, W.S. 1964. Additional bird recordsfor interior Alaska. Condor 66:308.

Accepted 18 February 2000

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