SEASONAL STATUS OF THE AMERICAN PIPIT IN

DANIEL M. TAYLOR, 244 N. 12th, Pocatello,Idaho 83201

In Idaho, the AmericanPipit (Antbus rubescens)has been considered primarilya migrant,either locally common but erratic (Larrison et al. 1967) or uncommonin springand commonin fall (Burleigh1972). Severalother writers(Merriam 1891, Merrill 1898, Newhouse1960, Levy 1962) consid- ered it an abundantfall migrantbut gaveno indicationof actualnumbers. The one (Larrisonet al. 1967) or two (Burleigh1972) winterrecords were from Lewiston.Larrison et al. (1967) suspectedthat pipitsmight breed on someof the state'shigh mountains,while Burleigh(1972) knew of only Merriam's(1891) statementthat they breedin the Mountains and a report by L. B. McQueenof breedingin the upper Pahsimeroi drainagenear . This scantinessof breedingevidence may be why the mostrecent A.O.U. checklist(1983) statesthat the AmericanPipit breedslocally on mountaintopsin severalRocky Mountain states but does not specificallylist Idaho. In this paper I consolidateand enhancewhat is known aboutAmerican Pipit distributionin Idaho with reference to adjacent areas. I present evidenceof additionalbreeding, concentrations of thousandsof fall mi- grants,and the species'regular but erraticwintering in much of southern Idaho.I analyzeChristmas Bird Countdata for patternsin winterdistribu- tion relatedto differencesin weather,elevation, geography, and annual variability.

METHODS

I gatheredrecent American Pipit recordsfrom a literaturereview and my own fieldnotes for the last 15 years.All ChristmasBird Counts(CBCs) for Idahosince 1978 were included,as well as somefrom adjacentMontana and Washington.Long-term counts from southernIdaho were examined statisticallyin a mannersimilar to that of Lauranceand Yensen(1985) and Dunning and Brown (1982). Weather data were extracted from U.S. EnvironmentalData Servicemonthly reports from eachweather station in or closeto eachCBC. Usingnumber of birdsper party-hour,I compared differencesbetween areas and betweenyears by analysisof variance (ANOVA),and examinedinfluences of weatherand elevationby multiple regression(Zar 1974). This wasdone on a MacintoshSE computerwith a Statviewstatistical package. I alsosurveyed the extensivemudflats at the mouthof the New York Canal, Lake Lowell,Canyon Co., for American Pipits18 timesfrom August through November 1990.

RESULTS Breeding In the SawtoothMountains I observedan adultAmerican Pipit feeding a youngbird on the CusterCo. sideof the summitalong the trail between Western Birds 25:43-49, 1994 43 AMERICAN PIPIT IN IDAHO

Toxawayand Alice lakes,elevation 2775 m, on 26 July1989 andan adult behavingterritorially near Alpine Lake, CusterCo., elevation2625 m, on 3 August 1993 (Figure 1). I found a pair of pipits giving alarm calls and carryingfood in theirbeaks in the Henry'sLake Mountains,elevation 2850 m, FremontCo., on 29 July 1993. C. Trost (pers.comm.) found several nestingpairs with young at the headof the eastfork of the PahsimeroiRiver on 25 July1976 [AmericanBirds (AB) 30:981] and a neston ,Big LostRange, Custer Co., elevationabout 3200 m. Roberts(1992) foundAmerican Pipits in the nestingseason between 2400 and 3050 m in the Lemhi and Beaverhead ranges and at Long Tom Lookout, ChallisCreek Lakes, and Taylor Mountainbetween the Middle Fork and main Salmon Rivers. These locationsmight be consideredpart of the Salmon Mountainsof Merriam (1891). FallMigration At Lake Lowell (Figure1) in 1990, no AmericanPipits occurredin August,and I foundonly one to fouron fivedates from 6 to 18 September. On 27 Septemberthere were 600, and numberspeaked at 1750 on 9 October.There were stillhundreds by 16 and 18 October,and from late Octoberto mid-Novemberdozens remained. A few lingeredinto December. At thissame location J. Gatchetestimated pipits gathered in the thousands in the lastweek of September1991 (AB 46:125). Largenumber of pipitshave been reported from otherlocations in Idaho and adjacentareas in lateSeptember or October.Thousands were at Rupert in fall 1971 (AB 26:98). I foundflocks of over100 on farmlandin the Dry Lake regionof CanyonCo. in the lastweek of October1976, and 140 at AmericanFalls Reservoir, Power Co., on 22 September1990. In eastern Washington500 wereat BanksLank on 17 September1983 (AB 38:226), 200 were at Spokane on 8 October 1972 (AB 27•0), 2000 were at O'SullivanDam on 9 Oct 1971 (AB 26:91), and at least 1000 were near Reardan on 21 September 1973 (AB 28:81). Hundreds were found in alpinemeadows on SteensMountain, Oregon, on 24 September1983 (AB 38:226), 2000 were estimatedat BrighamCity, Utah, on 22 October 1972 (AB 27:298), and thousandswere in Cache Valley, Utah, on 5 October 1942 (Bent 1950).

Winter In winter,the AmericanPipit is unrecordedfrom northern Idaho, except at Lewiston,the state'slowest elevation, where Burleigh (1972) livedfrom 1948 to 1958 andrecorded pipits only twice: a singlebird on 21 December 1951 and a flock of 60 on 8 and 13 January1954. The 33 CBCs conductedat Moscow,Indian Mountain,Sandpoint, and Coeur d'Alene from 1978 to 1991 recordedno pipits.There were also no pipitson the northwesternMontana and easternWashington CBCs at Troy, Libby, GlacierNational Park, Big Fork, or Spokaneduring this time. In central Idaho,the two CBC areasof SunValley and Salmon recorded pipits just once in 14 years,but a total of 86 at Salmon in December1986. The Missoula,Montana, CBC has had justone pipit once, and a recordfor 17 44 AMERICAN PIPIT IN IDAHO

December1989 at NinepipeNWR (AB 44:297) was apparentlyonly the second for western Montana in winter. Pipitshave been found erraticallyin winter on CBCs in southernIdaho (Table1). Perhapsbecause of high variability,there were no significant differencesin numbersof pipitsbetween any of the nine southernIdaho CBC areas(ANOVA, P > 0.10 in all comparisons;Bruneau was excluded owingto its shortduration). Pipits have been recorded in about45% of the yearson the sevenof the ten CBCswhere they havebeen found more than once, but no count found them more than 58% of the time. The highest

BRITISH COLUMBIA

n Glacier N,P. 0 Troy nt[] Libby g o BigFork Spokane 0

Coeur 'd MONTANA

Moscow O Mtssoula

Lewtston'

o o Salmor o Henrys Mountatns ß

o

SawtoothMountains ß Big Lost ß 0 0 Rexl' Nampa Sun Valley Boise Falls 0

Bruneau Hagerman ] lcan Fails Reservoir Falls Rupert

NEVADA UTAH

Figure1. Locationsmentioned in the text. Solidcircles, known breeding locations; open circles,probable breeding locations; solid squares, locations of ChristmasBird Counts.

45 AMERICAN PIPIT IN IDAHO

Table 1 Numbersof AmericanPipits on ChristmasBird Counts in Southern Idaho from 1978 to 1991

Elevation Yearsof High Mean_+ SE a (Range) Area (feet) count count pipits/party-hour

Nampa 2210 14 (7)b 242 0.327_+ 0.223 (0-3.15) Bruneau 2455 7 (4) 326 1.601 _+1.306 (0-9.30) Boise 2700 14 (5) 30 0.039 _+0.022 (0-0.95) Hagerman 2900 13 (6) 34 0.135 _+0.072 (0-0.95) Twin Falls 3170 12 (4) 423 1.174 _+1.096 (0-13.22) Rupert 4150 14 (6) 70 0.382 _+0.277 (0-3.91) Am. Falls 4180 14 (8) 23 0.059 _+0.023 (0-0.29) Pocatello 4200 14 (1) 1 0.001 _+0.001 (0-0.02) IdahoFalls 4610 14 (0) 0 0 Rexburg 4800 14 (1) 200 0.510 _+0.510 (0-7.14)

aSE,standarderror. /•Numberof yearswith pipits on count. numberon any count was 423 at Twin Falls in 1986, and Nampa, Bruneau,and Rexburgeach had a singlecount with over 100 pipits. Althoughthe three southernIdaho CBCs at the highestelevations recordedpipits on onlytwo of 42 counts,pipit numbers were not signifi- cantlycorrelated with elevation(Table 2). Therewas no significantassocia- tionof the abundanceof AmericanPipits on CBCswith the climatic factors of minimum snow, mean Decembertemperature, or mean December precipitation(Table 2). The 200 pipitsin 1979 constitutingRexburg's only recordwas one of the fewyears there without snow on the ground,and the Twin Fallspeak of 423 alsocoincided with a CBC free of snow.However, therewere 3 inchesof snowin Nampawhen 175 pipitswere found, while Bruneau recorded 279 with one-half inch of snow and 44 with 3 inches of snowand temperaturesof -22 to -32 ø C.

Table 2 Relation of Various Climatic Factors and Elevation with American Pipit Numbers on Combined Idaho Christmas Bird Counts, 1978-1991 a

Factor F testa

Minimumsnow depth 0.547 (0.593) 0.46 (0.44) 0.01 (0.01) Elevation 1.303 (0.414) 0.28 (0.52) 0.02 (0.01) MeanDecember precipitation 0.008 0.928 <0.01 MeanDecember temperature 1.731 0.19 0.02

aF-testvalues of multipleregression for all counts,and in parenthesesall countsexcept IdahoFalls, Rexburg, and Pocatello,excluded because of theirhigher elevation. /•Probabilityvalues of F tests. CAmountof variationexplained by thesefactors. 46 AMERICAN PIPIT IN IDAHO

For all southernIdaho CBCs combined(Bruneau excluded because of its shorter duration), numbersoi: pipits were highest in 1979, 1981, and 1986. The numberof pipitsper party-hourwas significantly higher in 1986 than in mostother years (ANOVA, P < 0.05), but thiswas probably due to the singlevery largetotal at Twin Falls.In yearswith few birds,pipits were stillfound on at leasttwo CBCs, exceptin 1983 when only four birdswere at Rupert.In the three yearswith the highestcounts three or four CBC areasstill lacked pipits.

DISCUSSION

The two new definitebreeding records and other midsummerobserva- tions further establishthe American Pipit as a breedingspecies in Idaho. The alpinezone in the statehas been inadequatelysurveyed, and it is likely there are more areasin the high countrythat supportpipits, especiallyas breedingpipits are known from adjacent alpine zones in Yellowstone NationalPark and on the BeartoothPlateau, Wyoming (McEneaney 1988, Hendricks1991), and in the Wallowa Mountainsof northeastOregon (Gabrielsonand Jewett 1940). Whether the new Idaho recordsreflect a recent increaseof the breedingpopulation, as in the Sierra Nevada of California (Miller and Green 1987), is indeterminable. Late Septemberand October may be the time of peak pipit movement throughIdaho and adjacentregions becuase the specieswaits to migrate untilit completesits postnuptialmolt, which occursin Augustand Septem- ber (Bent 1950, Verbeek 1973). The winter absenceor extremerarity of AmericanPipits in northernand central Idaho is consistent with their avoidance in the western of dry-beltpine forest (Root 1988). Numbersof winteringpipits in southern Idahodo not appearto be governedby weatheror elevation.Root (1988) found that in the eastern United States the subspeciesA. s. rubescerts wintersin areasof averageJanuary temperature greater than -1 ø C, but in the western United States pipits are hardier, wintering in areas with minimumJanuary temperatures as low as -7 ø C. Pipits appear to winter in southern Idaho randomly. The variation recordedon CBCs may be due in part to the countsthemselves. However, the patternof one or a few pipitssome winters and many pipitsin a few wintersis similarto what Burleigh(1972) foundin Lewiston,what I have observedat Lake Lowell, and what Littlefield (1990) found at Malheur NationalWildlife Refuge, southeastern Oregon. Erraticannual fluctuations have alsobeen foundin sparrowswintering in the northernGreat Basin (Lauranceand Yensen1985) and SnowyOwls (Nycteascandiaca) winter- ing on the Great Plains(Kerlinger and Lein 1988). In Europe,the closely relatedWater (Antbus spinoletta) and other winteringpipits responded almostimmediately to a new food sourcecaused by canal dredging(van Ardenne 1986), and the AmericanPipits I observedin late October 1976 were directlybehind a plow. Numbersof AmericanPipits wintering in Idaho may reflectthe species'ability to respondquickly to erraticfood sources. It is possiblethat winteringof pipitsin southernIdaho is recent.Before the 1970s there were few ornithologistsin winter in southernIdaho, but 47 AMERICAN PIPIT IN IDAHO

Davis(1934) spent 1919-1921 in the Rupertarea, and PierceBrodkorb collectednumerous rare and uncommonwinter birds throughout southern Idahoin the early1930s (Burleigh1972). Bothfailed to recordpipits at this season.Earlier in the century,however, pipits were known to winterin both southeasternOregon (Gabrielson and Jewett 1940) and the OgdenValley, northeasternUtah (Bent 1950), so I suspectthe lack of early recordsin southernIdaho was due to the paucityof observers,not pipits.

SUMMARY

In Idaho, AmericanPipits breed in the Pahsimeroi,Lemhi, Lost River, and Sawtoothmountains, and probablyin the Beaverhead,Henry's Lake, and Salmon River mountains.Migrating pipits sometimesconcentrate in the thousandsin Idahoand adjacentareas in late Septemberand October. In winter, pipits are absentfrom northern Idaho and adjacentregions, extremelyrare in centralIdaho, and erratic but occasionally numerous in the southernpart of the state.There are no significantcorrelations between numbersof pipitson southernIdaho Christmas Bird Countsand elevation, snowcover, mean Decemberprecipitation, or mean Decembertempera- ture.There are no significantdifferences in pipitnumbers between different ChristmasBird Countareas. In one year, I986, numbersof pipitswere significanfiyhigher than in manyother years from 1978 to 1991, butthis wasprobably due to one exceptionallyhigh count at Twin Falls.

ACKNOWLEDGMENTS

Thispaper was improved significanfiy by reviewsby N. A. M. Verbeekand David F. DeSante.

LITERATURE CITED

AmericanOrnithologists' Union. 1983. Checklistof NorthAmerican Birds, 6th ed. Am. Ornithol. Union, Lawrence, KS. Bent, A. C. 1950. Life historiesof North Americanwagtails, shrikes, vireos, and their allies. Bull. U.S. Natl. Mus. 197. Burleigh,T. D. 1972. Birdsof Idaho.Caxton, Caldwell, ID. Davis,W. B. 1934. An analysisof thebird population in thevicinity of Rupert,Idaho. Condor 37:233-238. Dunning,J. B. Jr., and Brown,J. H. 1982. Summerrainfall and winter sparrow densities:A testof the foodlimitation hypothesis. Auk 99:123-129. GabrielsonI. N., and Jewett,S. G. 1940. Birdsof Oregon.Ore. StateUniv. Press, Corvallis. Hendricks,P. 1991. Site fidelityand renestingof femaleAmerican Pipits. J. Field Ornithol. 62:338-342. Kerlinger,P., and Lein, M. R. 1988. Populationecology of SnowyOwls during winter on the Great Plains of North America. Condor 90:866-874. barrison,E. J., Tucker,J. L., and Jollie,M. T. 1967. Guideto IdahoBirds. J. Ida. Acad. Sci. 5:1-220.

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Laurarice,W. E, andYensen, E. 1985. Rainfalland winter sparrow densities: A view from the northern Great Basin. Auk 102:152-158. Littlefield,C. D. 1990. Birdsof MalheurNational Wildlife Refuge. Ore. State Univ. Press, Corvallis. Lew, S. H. 1962. Additionalsummer southern Idaho bird notes. Murrelet 43:10- 14. McEneaney,T. 1988. Birdsof Yellowstone.Robert Rhinehart, Boulder, CO. Merriam,C. H. 1891. Resultsof a biologicalreconnaissance of south-central Idaho. N. Am. Fauna 5:1-108. Merrill, d.C. 1898. Notes on the birdsof Fort Sherman, Idaho. Auk 15:14-22. Miller,d. H., and Green,M. T. 1987. Distribution,status, and originof Water Pipits in California. Condor 89:788-797. Newhouse,V. F. 1960. Birdsof selectedirrigated river valleys of west-centralIdaho. Murrelet 41:1-6. Roberts,H. B. 1992. Birdsof east-centralIdaho. NorthwestPrinting, Boise, ID. Root, T. 1988. Atlas of WinteringNorth AmericanBirds. Univ. ChicagoPress., Chicago. Van Ardenne,J. 1986. Use of an unpredictedfeeding area by pipits(Antbus spp.) and White Wagtails(Motacilla alba). Limosa59:141. Verbeek,N. A.M. 1973. Pterylosisand timingof molt of the WaterPipit. Condor 75:287-292.

Accepted 15 August 1993

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