WESTEKN BIRDS Volume 28, Number 1, 1997 THE TIMBERLINE SPARROW, SPIZELLA (BREWERI) TAVERNERI, IN ALASKA, WITH NOTES ON BREEDING HABITAT AND VOCALIZATIONS TERRYJ. DOYLE, TetlinNational Wildlife Refuge, P.O. Box 779, Tok,Alaska 99780 The TimberlineSparrow was originally described as a fullspecies, $pizella taverneri,by Swarth and Brooks (1925), whodistinguished it from Brewer's Sparrow,Spizella breweri,by itsdarker color, heavier streaking, and larger averagesize but smaller,slenderer, darker bill. Subsequently,ornithologists haveclassified the TimberlineSparrow as a subspeciesof Brewer's,though Sibleyand Monroe(1990) rankedit as a full speciesagain, on the basisof unpublisheddifferences in vocalizationsand ecology. The publishedbreeding range of taverneri extendsfrom southwestern Yukon Territory, northwesternand central British Columbia, and west- central Alberta to southeastern British Columbia and southwestern Alberta (AOU 1957), where it approachesthe north end of the rangeof nominate breweri.The winterrange is poorly known, with mostU.S. specimenstaken during migration, in Arizona (Monson and Phillips 1981), New Mexico (Grinnell1932), Texas (Oberholser1974), and Washington(Jewett et al. 1953). Only one winterspecimen has beenreported, from California(Rea 1967), suggestinga winter rangesouth of the U.S. On 22 June1992, JeffreyJ. Boutonof the NationalPark Servicefound a singingmale TimberlineSparrow in the NutzotinMountains of Alaska, 100 km northwestof the species'closest known location in Yukon(Clarke 1945, PamelaH. Sinclairin litt.).Over the followingfour years I studiedthe occurrenceand statusof this speciesin Alaska.I characterizedits habitat, recordedsongs, and collectedspecimens (University of AlaskaMuseum, Fairbanks)to document its occurrenceand to help shed light on the relationshipbetween taverneri and nominatebreweri. STUDY AREA I searcheda 15-km 2 area near Gold Hill from 1993 to 1995 and an 8-km 2 areain the Upper Cheslinadrainage from 1994 to 1996 (Figure1). In addition, Western Birds 28:1-12, 1997 1 THE TIMBERLINE SPARROW IN ALASKA an independentgroup visited Gold Hill in 1996. Gold Hill is in the Nutzotin Mountains10 km northeastof Chisana,Alaska (62 ø 06' N, 141ø 54' W). The UpperCheslina drainage is in the Mentasta Mountains 80 kmnorthwest of Gold Hill (62ø 39' N, 142ø 44' W). The Mentastaand Nutzotin mountains are part of theAlaska Range, which extends east to theWhite River in Yukon(Orth 1971); the KluaneRange continues east of the WhiteRiver. Habitatswithin the GoldHill and Upper Cheslinaareas are similar(Figure 2) and may be describedwith Kessers(1979) nomenclature.Unvegetated screeslopes of ruggedmountain peaks, elevation 2300-2600 m, descendto rollingfoothills of alpineand subalpine vegetation. Mats of dwarfshrubs, <0.4 m high, in the alpinezone giveway to subalpinehabitat at approximately 1500 m in the GoldHill area and 1300 m in the Upper Cheslina.The alpine zone descendsmuch lower on north-facingslopes. Subalpine vegetation on south-facingslopes is composedof patchyopen and closedthickets of mediumwillows (Salix spp.) and alders (Alnus crispa), 1.2-2.4 m high,with DwarfBirch (Betula nana) a commoncomponent of the understory.Thickets of low shrubs,0.4-1.1 m high,dominate the subalpinezone of north-facing slopes.Dwarf spruce (Picea spp.) woodlands, <5.0 m highand <20% canopy cover,occur at elevationsbelow the subalpinezone, along with closed thickets of tall willowand alder,2.5-4.9 m high. RESULTS Status in Alaska TimberlineSparrows were observedin the GoldHill area eachyear from 1992 to 1996. Observationsincluded an adult feedinga recenfiyfledged juvenilein 1993 (Figure3), birdsgathering food in 1996, and up to six singingmales within 8 km2 in 1994 (Table1). A singingmale was in the Upper Cheslinadrainage in 1994 but not in 1995 or 1996. Elsewhere,a singingmale at sealevel in southeastAlaska at Hyder,3-5 June1996, isthe onlyAlaska record away from the breedingground. All but one of the Alaska observationshave been during the breeding season,from mid-Juneto mid-July.A reconnaissanceof the Gold Hill area 3-5 June 1995 failedto disclosea singleTimberline Sparrow even though all of the regularbreeding birds of the areawere present (Upland Sandpiper, Bartrarnia 1ongicauda;Say's Phoebe, $ayornis saya; Horned Lark, Eremophila alpestris;Townsend's Solitaire, Myadestes townsendi; Ameri- can Pipit,A nthus rubescens; Orange-crowned Warbler, Vermivora cela ta; Wilson's Warbler, Wilsonia pusilla; American Tree Sparrow, $pizella arborea;Savannah Sparrow, Passerculus sandwichensis; White-crowned Sparrow,Zonotrichia leucophrys;Smith's Longspur, Calcarius pictus). A later trip, 25-26 June 1995, revealed three Timberline Sparrows in locationswhere they had been presentin prior years.The earliestthat Swarth(1936) foundthe sparrowsin the Atlin regionof BritishColumbia was 29 May, and recentarrivals near Whitehorse,Yukon, have been from 29 to 31 May (Cameron D. Eckert, Pamela H. Sinclair in litt.). The observationat Hyder in earlyJune suggests that the birdsare stillmigrating at that time. It isnot surprisingthat the TimberlineSparrow arrives relatively THE TIMBERLINE SPARROW IN ALASKA I i 143 ø 142 ø Teain A A G T'ah A A Upper A • GoldHill 62 ø :.: , , I A 0 1020 30 mi : AlaskaIYukon 143 ø 142 ø 141 ø 140 ø I I i i Figure1. Locationsof TimberlineSparrow records in Alaskaand adjacent Yukon Territoryare denotedby solidtriangles. latein the GoldHill area,given that the knownbreeding range in Alaskais farther north than that in Yukon and British Columbia. Despitethe sparrows'late arrivalon the breedingground, their singing seemedto diminishby early July. The latestthat they were found singing was THE TIMBERLINE SPARROW IN ALASKA Figure2. BreedingTimberline Sparrows in Alaskawere foundon south-facingslopes at the transitionof the alpineand shrubbysubalpine zones. The habitatin whichthey were foundalmost exclusively was thickets of shrubbywillows 1.0-1.2 m high with a Dwarf Birchunderstory 0.4-0.5 m high. This habitatdid not occuron north-facing slopeswithin the area studied.as seenon the right sideof this canyon. Photo by Terry J. Doyle 4 July. Three were seen but not heard singingin the Gold Hill area from 2 to 17 July, and the singingmale in the Upper Cheslinadrainage was not heardthree weekslater, on 15 or 16 July. Departure dates are unknown, but Swarth (1936) found Timberline Sparrowson the breedinggrounds near Atlin, BritishColumbia, until early September. Habitat I found breeding Timberline Sparrows in Alaska to be restrictedto a narrow band at the transition between the subalpine and alpine zones, vegetatedwith low to mediumthickets of willows(Figure 2). Averagecanopy height rangedfrom 1.0 to 1.2 m, canopycover from <25% to 50%. Salix glauca wasthe dominantwillow: S. planifolia and S. brachycarpawere less common. Dwarf Birch was the primary componentof the next tallestshrub layer, with Vaccinium uliginosum and Potentilia fruticosa as subdomi- nants. Average canopy height of this layer was 0.4-0.5 m, and canopy coverwas <25%-75%. Groundcover included Rhododendron !apponicum, Salix reticulata, Poa sp., Carex sp., Mertensia sp., and trace amountsof ferns, mosses, and lichens. THE TIMBERLINE SPARROW IN ALASKA Figure3. This adultTimberline Sparrow was feedinga recentlyfledged juvenile at Gold Hill on 17 July 1993, providingthe firstdocumented record for Alaska. Photo by David W. Sonneborn All TimberlineSparrows were found on rather steep (30-40 ø) south-to southeast-facingslopes at 1460 to 1525 m in the GoldHill areaand at 1325 m in the Upper Cheslina.Below this elevation shrubs are tallerand canopies more closed;above. the vegetationquickly changes to matsof dwarfshrubs. Timber- lineSparrows were foundin contiguousbands of willowthickets rather than in smallpatches of willows.Some individualTimberline Sparrows appeared to prefer the micro relief in ravines.which has also been observedin Yukon (CameronD. Eckertpers. comm.). No TimberlineSparrows were found on north-facingslopes, which lack the medium-heightthickets of willows. The habitatin which Timberline Sparrowsoccurred was quite predictable. I flew over the Gold Hill area in 1994 in a fixed-wingaircraft and identified potentialTimberline Sparrow habitaton the basisof the prior year's field work.All potentialTimberline Sparrow habitat, within the 15 km2 surveyed on the ground, had singingmales in 1994. No Timberline Sparrowswere foundoutside the identifiedhabitat. In 19951 identifiedpotential Timberline Sparrowhabitat from a fixed-wingaircraft over a 4600-km2 area in the Mentastaand Nutzotin mountainsfrom northwestof the Upper Cheslina drainage to the Yukon border. Approximately 61 linear kilometers of potentialhabitat were identified,the majoritybetween Gold Hill and the Canadian border. Several areas more extensivethan those investigatedin thisstudy were identified.as were severalsmall patches <1 km long. Nearly all identifiedhabitat was on steep south-facingslopes, consistent with that found at Gold Hill and the Upper Cheslina. THE TIMBERLINE SPARROW IN ALASKA Table 1 Dates, locations,and observersof TimberlineSparrow sightings in Alaska. Date Location Observations Oberservers 22 June1992 GoldHill One singingmale JeffreyJ. Bouton 17 July1993 GoldHill Adultfeeding a T.J. Doyle, recentlyfledged PhilipD. Martin, juvenile DavidW. Sonneborn 18-19 June1994 GoldHill Six singingmales T.J. Doyle 24 June 1994a Upper Cheslina One Singingmale T.J. Doyle, Ryan C. Means 25-26 June GoldHill Threesinging males T.J. Doyle, 1995b GaryH. Rosenberg 3-5 June1996 Hyder One singingmale