WILLOW FLYCATCHER SURVEYS IN THE

JOHNH. HARRIS,Department of Biology,Mills College, Oakland, 94613 SUSAN D. SANDERS, 133 North St., Woodland, California95695 MARY ANNE FLETT, 1764 Newell Ave., Walnut Creek, California94595

The Willow Flycatcher(Empidonax traillii) was formerly a common sum- mer residentin California, breedingin riparian willow thickets.It has been extirpatedfrom mostof itsCalifornia range, and is currentlyunder considera- tion for state Threatened or Endangeredstatus (R. Schlorffpers. comm.). Most of the remainingpopulations occur in isolatedmountain meadowsof the Sierra Nevada and alongthe Kern, Santa Margarita,and San Luis Rey rivers (Remsen 1978, Serena 1982, Unitt 1987). The CaliforniaDepartment of Fish and Game conducteda surveyfor Willow Flycatchersin six Sierra Nevada nationalforests and in 1982 (Serena 1982). This paper describesthe resultsof the 1986 Willow Flycatchersurvey in the SierraNevada and summarizesinformation about the species'status in Califor- nia. The purposesof our studywere to surveysites at whichWillow Flycatchers had been previouslyseen, searchfor new sites,and attemptto refine our knowledgeof the species'habitat requirements.

METHODS

We conductedour surveysbetween 23 June and 31 July 1986 in order to minimizethe likelihoodof countingmigrant birds. Studies at Dinkey,Poison, and Long meadowsin the SierraNational Forest (Stafford and Valentine1985) suggestthat Willow Flycatchersfrequently arrive at their breedinglocation aslate as mid-June,occasionally as late as early July. In the samearea, Willow Flycatchersdepart at any time from the end of July to late August, with a peak in mid-August.During the 1982 surveysome siteswere visitedin the first week of June. Birds observed at this time could have been migrants. We conductedour surveysearly in the morning, generallyfrom sunrise until 1000. Spontaneoussinging declines after 1000 (King 1955, Flett and Sanders 1987), although individualscan be heard at any time of day. A second,less intense, period of singinggenerally occurs before dusk. At each site, we walked alongthe perimeterof all willow habitat, listeningand play- ing taped songsand calls of Willow Flycatchers.We recordedthe number of singingmale Willow Flycatchersat each site and mapped the locationsof all Willow Flycatcherson sketchedmaps of the sites.A significantfraction of the singingmales may remain unpairedthrough the breedingseason, as current studies on the Little Truckee River and Shaver Lake area indicate (Flettand Sanders1987, Staffordand Valentine1985). The assumptionthat singingmales represent pairs may thuslead to an overestimateof the number of breedingbirds. On the other hand, songfrequency declines after pairing (Staffordand Valentine1985); thussuccessfully paired males may be missed in a song survey.

Western Birds 18:27-36.1987 27 WILLOW FLYCATCHER SURVEYS

During 1982 the lnyo, Sierra, Stanislaus,Tahoe, Plumas, and Lassen nationalforests were surveyed(Serena 1982). Other areassurveyed includ- ed The Nature Conservancy'sKern River Preserveand Yosemite National Park. We visitedmost of the sitesof the 1982 survey,including all locations which had Willow Flycatchersin 1982 or subsequentyears. New areas of coverageincluded portions of the El Dorado,Toiyabe, and Sequoianational forests,Sequoia National Park, and KingsCanyon NationalPark. We also visitednew sitesin the Lassen,Plumas, lnyo, Sierra, and Tahoe national forests.

RESULTS

We visited125 sitesduring the 1986 survey,recording 110 singingmale Willow Flycatchersat 30 sites.In addition,we have receivedreports of an additional6 birdsin the Sierra/Cascadesregion, for a total thusfar of 116 singingmales. Fifty-sixof the sitesvisited were not surveyedin 1982. These siteswere addedto the surveyon the basisof suggestionsby biologistsand sightingsof Willow Flycatchersbetween 1982 and 1986. Visitsto thesenew sitesresulted in sightingof 11 singingmales at 6 of the sites.Areas with more than 2 singingmales are shownin Table 1. The NatureConservancy's Kern River Preservehad the largestnumber of singingmales (39). The preserve containsseveral miles of ripariancottonwood-willow forest (Populus fremontii, $ai•x iaevigata,and $. gooddingii).The LittleTruckee River drainage, which had the largestnumber of singingmales in 1982, had 25 in 1986. This area

Table 1 WillowFlycatcher Concentrations in the SierraNevada 1982-1986'

Location 1982 1983 1984 1985 1986

Perazzo Meadow (Tahoe N.F.) 11 17 12 8 11 Lacey Valley (Tahoe N.F.) 13 14 10 12 7 Little Truckee R. Total (Tahoe N.F.) 39 ------25 Kern River Preserve (Nat. Conserr.) 26 -- 23 29 39 Shaver Lake Area (Sierra N.F.) 10 -- 15 8 9 Beasore Meadow (Sierra N.F.) 2 ------4 Hodgdon Meadow (YosemiteN.P.) 2 -- -- 3 1 Ackerson Meadow (StanislausN.F.) 5 ------2 • Westwood Meadow (Lassen N.F.) 4 ------6 Gurnsey Meadow (LassenN.F.) 0 ------3 Faith, Charity Valleys (ToiyabeN.F.) .... 5 KlamathRiver (SiskiyouCo.) ------3 c --

ßFor eachsite the numberof singingmale Willow Flycatchers is indicated for yearsin whichsurveys havebeen conducted. The tableincludes all sitesthat hadmore than 2 singingmale Willow Flycat- chersat sometime duringthe studyperiod. Only sitesin the SierraNevada and Cascaderanges areincluded. A totalis given for the LittleTruckee River drainage, which includes Perazzo Meadow and Lacey Valley. 'Reportsindicate that there may have been 3 singingmales (J. Winter pers. comm.). 'Reported by M. Robbins.

28 WILLOW FLYCATCHER SURVEYS includes extensive meadows near Webber Lake, Perazzo Meadow, and ad- ditionalmeadows along the Little Truckee River west of Highway 89. The Shaver Lake area, Sierra NationalForest, had 9 singingmales. This area in- cludesDinkey, Long, and Poisonmeadows. Dinkey Meadow had 6 singing malesin 1982 and 3 singingmales in 1986. The LittleTruckee River, Kern River,and ShaverLake areastogether account for 6756 of the WillowFlycat- chersightings in the Sierraduring 1986. Thesethree areas accounted for 73 56 of the Sierra Nevada sightingsduring 1982. Roughlythe samenumber of birdswas seen at the sitessurveyed in both 1986 and 1982 (99 in 1986, 103 in 1982). Sevensites that hadWillow Flycat- chersin 1982 had nonein 1986. Six of thesesites had onlyone birdin 1982. Six additionalsites decreased in number. Most importantamong this group wereLacey Valley (declinedfrom 13 to 7), LittleTruckee River (one site de- clinedfrom 8 to 2), and Dinkey Meadow (declinedfrom 6 to 3). Three sites that had no Willow Flycatchersin ,1982 had birdsin 1986. In two casesthree birdswere presentin 1986, in the other casetwo birdswere present.Seven additionalsites increased in numbersof Willow Flycatchers.Most important amongthese were Westwood(increased from 4 to 6), BeasoreMeadow (in- creasedfrom 2 to 4), Long Meadow (increasedfrom 1 to 3), and the South Fork of the Kern River (increasedfrom 26 to 39). The three mostnumerous Sierran populations have beensurveyed during at least4 of the last5 years.Perazzo Meadow and LaceyValley are two Little TruckeeRiver sitesthat have been consistentlysurveyed over the lastfive years.The PerazzoMeadow population has fluctuated, but there were the samenumber of singingmales in 1986 and 1982. The LaceyValley popula- tionappears to be declining,and accountsin partfor the overalldecline along the Little Truckee River. The Shaver Lake area (9 sites) has been studied intensivelysince 1983. The populationduring 1985 and 1986 was smaller than that in 1982. Dinkey Meadow had 6 singingmales in 1982 (thismay have been an overestimate,B. Valentinepers. comm.), but has had 3 in all subsequentyears except 1985, whenthere were only 2 singingmales. Long Meadow, whichhad only 1 singingmale in 1982, has had 3 in every year since1984. The Kern Riverpopulation apears to have increasedsteadily since 1984. The increaseis distributedfairly evenly over the area. Grazinghas been eliminatedin severalof the areasof concentrationwithin the preservesince 1981 or 1982. Prince Pond, which has had as many as 13 birds, was ac- quiredby the NatureConservancy in 1982 and hasbeen ungrazed since 1983. MariposaMarsh, ungrazedsince 1981, hasincreased from 7 to 12 birdsin the lastthree years.Prince Pond had fewer birds(7) in 1986 than in the last two years,but the birdsmay havemoved to adjoiningflooded habitat. Flooded areaswest of PrincePond had at least6 singingmales where none had been sightedpreviously. These areasare not flooded every year. Willow Flycat- cher distributionon the Kern River floodplainmay be relatedto the distribu- tion of floodedareas in a givenyear. Grazedareas adjoining the preserve, such as Onyx and BloomfieldRanches, had no birdsthis year. Among the new sitesvisited, 6 siteshad Willow Flycatchers.A siteon the Feather River near Clio had 1 Willow Flycatcher.Other new sitesincluded one on the Little Truckee River (3 birds), Summit Meadow 2 (Shaver Lake area, 1 bird), Faith Valley and Charity Valley (ToiyabeNational Forest, 3 29 WILLOW FLYCATCHER SURVEYS and 2 birds,respectively), and Troy Meadow (SequoiaN.F., 1 bird; 1 has been seen in previousyears). The Faith Valley and Charity Valley sitesare only a few milesapart, and thereis someapparently suitable habitat nearby in Hope Valley, althoughwe did not locate singingmales there during the 1986 survey.

DISCUSSION

The Willow Flycatcherwas formerly consideredcommon and widely distributedin the state wherever suitablehabitat existed (Grinnell and Miller 1944). Areas where it was mostcommon includedthe Central Valley, the southerncoastal region, and centralCalifornia in general.Specific areas men- tioned in whichWillow Flycatcherswere commonor abundantinclude the KingsRiver (Goldman1908), the vicinityof BuenaVista Lake (Linton1908), the southcoast (Wilier 1912, 1933), swampythickets near Los Angelesand the valley riversof centralCalifornia (Belding 1890), the San FranciscoBay region (Barlow 1900), and Yosemite Valley (Grinnell and Storer 1924). Ridgwayconsidered it to be the mostabundant and generallydistributed Ern- pidonax species(cited in Belding1890). In the Sierra Nevada, Willow Fly- catcherswere felt to be commonalong willow-lined streams, especially in broad river bottomlands (Grinnell and Storer 1924, Grinnell et al. 1930, Sumner and Dixon 1953). Nestingsites were found from sea level to about 2500 m (8000 ft) (Grinnell and Miller 1944). As a breedingspecies, the Willow Flycatcherhas been extirpated from most of itsformer range, surviving only in mountainmeadows of the SerraNevada, andalong the south fork of theKern River, the Santa Margar•ita River, and the San LuisRey River(Remsen 1978, Garrettand Dunn 198!/, Serena1982, Unitt1987). As a springand fall transient, the Willow Flyca•:her isstill fairly commonin riparianwillow habitat throughout the state (McCaskie et al. 1979, Garrettand Dunn 1981). Willow Flycatchersno longerbreed in the Central Valley (McCaskieet al. 1979), and recordsfrom the southerncoast and cen- tral coasthave been sporadic (Stallcup and Greenberg1974, Garrettand Dunn 1981, Roberson 1985, Unitt 1984). Extensive searches in the Sacramento River Valley (Gaines1974) have revealedno breedingWillow Flycatchers. Carefulsearch of riparianhabitat in southernCalifornia in the summerof I978 revealedonly two singingmales (Garrettand Dunn 1981), althoughsubse- quent surveyshave revealedpopulations on the Santa Margaritaand San Luis Rey riversin San Diego County (L. Salatapers. comm., Unitt 1987). Even in the SierraNevada, the specieshas apparentlydeclined (Gaines 1977, Serena 1982), having become alarminglyscarce in the Yosemiteregion. Our surveyresults indicate that the majorityof SierraNevada Willow Fly- catchersare locatedin three generalareas. Betweenthe Little Truckee River (Tahoe National Forest) and Westwood Meadow (Lassen National Forest), we found 43 singingmales, most of whichwere alongthe LittleTruckee River (Table1). Nineteensinging males were foundin the centralSierra, from Acker- son Meadow (StanislausNational Forest) to the Shaver Lake area (Sierra National Forest). The south fork of the Kern River had the largestpopula- tion, with 39 singingmales. In additionto thesemajor areas,small numbers of singingmales were locatedon the eastside of the Sierra, near Mono Lake

3O WILLOW FLYCATCHER SURVEYS

(3 singingmales) and in the vicinityof CarsonPass (5 singingmales). There is a largegap in the distributionof sightingsbetween the centralSierra and the Kern River.There havebeen a few reportsin recentyears of WillowFlycat- chersin the Sequoiaand KingsCanyon National Parks (L. Norrispets. comm. to R. Schlorff)but no birdswere found duringthis year'ssurvey, and there seemsto be insufficienthabitat to support large populations. Portionsof northernCalifornia, particularly the areanorth of LassenNational Forest,from the Nevada borderto the coast,should be surveyedin the future. Duringour survey,a singingmale was locatedalong the FeatherRiver, near Clio. Thissite was visited briefly, and thereappears to be moresuitable habitat that shouldbe surveyedin the future. Singingmales have been reported in recentyears from the forksof the Salmon (1), the vicinityof Mr. Shasta(1), and LowerKlamath Lake (3 nests)(M. Robbinspets. comm.). Singingmales have been reportedfrom HumboldtCounty in the vicinityof Garbervil]e(R. LeVal]eypets. comm.) and from WillowCreek (Serena1982). Thesesightings may havebeen of migrants(R. LeVa]]eypets. comm.). RecentBreeding Bird Surveyshave produceda few sightingsin the northerntier of counties(S. Drogepets. comm.). There are 29 surveyroutes in Humboldt,Trinity, De] Norte, Siskiyou,Shasta, and Modoc counties.Seven of these routeshave recordedWillow Flycatchersduring the periodfrom 1982 to 1985 (4, 3, 3, and 6 birdsin the four years). A singlemale was observedat the Modoc Na- tional WildlifeRefuge for the firsttime in 1985, and a pair fledgeda single youngthere in 1986 (W. Radke pets. comm.). This successfulnesting may have resultedfrom protectionof riparian habitatover the last 6 years. Fur- ther surveysin northernCalifornia wi]] likely produce more sightings,but there is no indicationthat large populationsoccur in this region. The subspecificidentity of CaliforniaWillow Flycatcherpopulations pro- videsfurther reasonfor concernabout the speciesstatus in the state. Three subspeciesoccur in California(Unitt 1987). Empidonaxtrai!!ii brewsteri breeds from FresnoCounty north, from the coastto the Sierra Nevada crest.Em- pidonastraiilii adastus breeds east of the Sierra/Cascadeaxis. The t•pe localit• for this taxon is in southernOregon, and it is known to range into Modoc County (Phillips1948) and perhapssouth to northernInyo county (Unitt 1987). WillowFlycatchers in northernCalifornia may representa zoneof in- tergradationbetween E.t. brewsteriand E.t. adastus(Phillips 1948). Southern Californiapopulations of WillowFlycatchers have recently been shown (Unitt 1987) to belongto the subspeciesE.t. extimusPhillips (1948). The northern limitsof breedingfor thistaxon are Independencein the OwensValley, the southfork of the Kern River, and the Los Anõelesbasin. It hasalso suffered seriousdeclines in the portionsof itsrange outside of California(Unitt 1987). Thusthe smallnumber of breedingWillow Flycatchers in Californiais further divided among three subspecies,each of which has declinedto very low numbers within the state. Remsen(1978) listedthe WillowFlycatcher as a speciesof highestpriori- ty, facingextirpation if currenttrends continue. In 1980, reportsfrom the Pacific coastand southwestregions led to the speciesbeing added to the Audubon Blue List (Arbib 1979). The Blue List for 1981 included Utah, Arizona, and New Mexicoas areasof concern(Tare 1981). In 1983, the KingsRiver Con- servationDistrict began studies of Willow Flycatchersat DinkeyMeadow and

31 WILLOW FLYCATCHER SURVEYS othernearby meadows in the vicinityof ShaverLake (Staffordand Valentine 1985). DinkeyMeadow, known to harborbreeding Willow Flycatchers, is due to be inundatedby the Dinkey Creek Hydroelectric Project. In 1984, theWillow Flycatcherwas added to the U.S. ForestService Region 5 SensitiveSpecies list.The U.S. Fishand Wildlife Service has also designated the WillowFlycat- cheras a SensitiveSpecies for Region1 (,Idaho, Oregon, Califor- nia,and Nevada) on thebasis of significantdeclines in thisregion (Sharp 1986). The WillowFlycatcher is currently under review for possiblelisting as a state Threatenedor EndangeredSpecies (R. Schlorffpers. comm.). Many authorsagree that alterationand lossof riparianhabitat, especially in the CentralValley, had a rolein the declineof WillowFlycatchers (Reinsen 1978, Garrettand Dunn 1981). However,the absenceof WillowFlycatchers in apparentlysuitable habitat suggests that other factorsare also at work. Brown-headedCowbird (Molothrus ater) nest parasitism has been suggested as a causeof the WillowFlycatcher's decline (Gaines 1974). Studiesat low elevationsin southernCalifornia suggested that the WillowFlycatcher is suscep- tibleto cowbirdparasitism (Hanna 1928, Rowley 1930). Friedmann(1963) reported150 instancesof Brown-headedCowbird parasitism of WillowFly- catchers,41 of whichwere reportsfrom southernCalifornia. Gaines (1974) concludedthat 9 of 12 species(including the Willow Flycatcher)known to havedeclined along the SacramentoRiver are highlysusceptible to cowbird parasitism.Decline of WillowFlycatchers in centraland coastalCalifornia coin- cideswith the spreadof cowbirdsin the 1920sand 1930s (Gaines1974, Gar- rett and Dunn 1981). The lackof overlapin breedingseasons between Brown- headedCowbirds and WillowFlycatchers in the ShaverLake area and the lackof observedparasitism (Stafford and Valentine 1985) suggestthat cowbird parasitismmay be lessimportant in the Sierra Nevada than at lower eleva- tions (but see Flett and Sanders 1987). Grazingin riparianhabitats has been suggested as a possiblefactor in decline of the Willow Flycatcherin the SierraNevada and elsewhere(Serena 1982, Staffordand Valentine1985, Taylor 1986, Flett and Sanders1987). Cattle canadversely affect Willow Flycatchers by disturbingnests (Stafford and Valen- tine 1985, Flettand Sanders1987) and by changingthe structuralfeatures of riparianhabitat such as meadowwetness (drying of meadowsby soilcom- pactionand gullying), willow foliage height, and willow foliage volume (Serena 1982, Taylor 1986). At the MalheurWildlife Refuge in Oregon,ungrazed transectshad higherwillow foliage density and volumeand hadmore Willow Flycatchersthan grazed transects (Taylor and Littlefield1986). Theseauthors alsopresent data indicatinga correlationbetween increases in Willow Fly- catchernumbers and decreasesin grazing.Other factors that might be involved in the decline of Willow Flycatchersin the Sierra Nevada include lossof meadowhabitat due to reservoirand hydroelectricdevelopment, fires set by grazers,Lodgepole Pine (Pinuscontorta) encroachment on meadows,and eventson the winteringgrounds (Serena 1982). The habitatrelationships of WillowFlycatchers in the SierraNevada were studiedby Serena (1982). Complete analysisof our habitatdata will be reportedelsewhere (Harris et al. 1987), but we presenthere a few briefcom- mentson the habitatpreferences of WillowFlycatchers. In agreementwith Serena(1982), we foundthat most birds (104 of 110)were in meadowslarger 32 WILLOW FLYCATCHER SURVEYS than 8 ha. Broad, flat areasseem to be preferred,as suggestedby Grinnell and Storer (1924) and Gaines (1977). Serena reported no associationbet- ween occurrenceof Willow Flycatchersand the wetnessof meadows.During our survey, Willow Flycatchersappeared to prefer wet meadows(see also Flett and Sanders 1987; Stafford and Valentine pers. comm.). Virtually all of the siteswith more than one singingmale had standingwater. Willow Fly- catcherswere only found wherethe willowcover was at least2 m high. The total amountof willowcover, obviouslycorrelated with meadowsize and per- cent coverof willow, is alsoimportant, though the percentagecover of willow alone may showno associationwith Willow Flycatcherpresence or absence (Serena 1982). Most of the siteswith Willow Flycatchershad highfoliage den- sity.Meadows in whichthe willowswere very arborescent,or in whichwillows had been severely"high-lined" by cattle, generallydid not supportWillow Flycatchers.Meadows with clumpsof willow separatedby openingswere preferredover solidmasses of willow,as suggested by Serena(1982), although WillowFlycatchers were sometimesfound at the edgeof suchmasses of willow.

SUMMARY AND MANAGEMENT RECOMMENDATIONS

The 1982 survey resultedin the observationof 103 singingmales in the SierraNevada. Nineteen sightings were reported in addition,giving a statewide total of 122 singingmales for 1982. Our surveysresulted in sightingsof 110 singingmales. We have also receivedreports of an additional6 birdsin the Sierra/Cascadesregion, for a totalthus far of 116 singingmales. Unitt (1987) and L. Salata (pers.comm.) suggestbreeding populations of about 15 pairs on the Santa MargaritaRiver and about 12 pairson the San Luis Rey River (both in San Diego County). This givesa statewidetotal for 1986 of about 143 singingmales. It appearsthat in Californiathe specieshas been reduced to a smallnumber of marginalpopulations. These belong to three subspecies, one of which (E.t. extimus) has declineddramatically in most of its range. Threer•atively smallareas account for abouttwo thirdsof the knownSierra Nevada population.With the two San Diego County populations,these ac- countfor 70 percentof the knownstatewide population of WillowFlycatchers. We believethat our resultsand the resultsof pastsurveys justify the follow- ing managementrecommendations:

1. The Willow Flycatchershould receive Threatened or Endangeredstatus becauseof its smallpopulation size, evidence of severedecline in numbers, and the concentrationof the majorityof the state'sbreeding Willow Flycatchers in five areas. This situationis criticalbecause the Little Truckee River popula- tion appearsto be declining,the Shaver Lake populationis threatenedby hydroelectricdevelopment, and two dams, which would flood much of the existingriparian habitat, have been proposedfor the Santa MargaritaRiver. Managementplanning should recognize the plightof all threeof the recognized subspeciesof Willow Flycatcheroccurring in Californiaand shouldaddress the preservationof genetic variation in this species. '). Futuresurveys should attempt to clarifythe statusof the speciesin areas not previouslysurveyed, including north coastal California, the KlamathMoun- 33 WILLOW FLYCATCHER SURVEYS

rainsand Cascades,and northeasternCalifornia in general. Areas of con- centrationshould continue to be surveyed. 3. Existingmeadow sitesshould be protectedfrom habitat loss (as from hydroelectricprojects or housingdevelopments). Acquisition of privateparcels or purchaseof conservationeasements by publicagencies or conservation organizationsmay be appropriate in some situations. •1. Planningfor the speciesshould recognize that a site that is unoccupied duringa given year shouldnot be consideredto be unsuitable,as it may be reoccupied.This is likelyto be importantespecially for smallsites. 5. Riparianvegetation should be protectedfrom grazingwherever possible, particularlywhere grazingis reducingfoliage density or dryingmeadow sites by soilcompaction and gullying.Furthermore, grazing in riparianzones should be curtailedduring June and July, when Willow Flycatchersare breeding. More studiesare needed to clarifythe effectsof grazingon riparian birds. 6. Furtherstudies are neededon the responsesof WillowFlycatchers to Brown- headedCowbird nest parasitism, particularly at lowerelevations. Experiments in cowbirdremoval would provide useful data and might enhance Willow Flycatcherpopulations. 7. Responseof Willow Flycatchersto revegetationand meadowrestoration should studied, as a possiblemeans of increasingthe amount of available habitatand of attractingWillow Flycatchersto otherwisesuitable meadows. Restorationof Willow Creek, Modoc County, providesan encouragingmodel for meadow restoration(Clay 1984).

ACKNOWLEDGMENTS

This studywas funded by the CaliforniaDepartment of Fish and Game (contract 1986-1529). RonaldW. Schlorffinitiated the studyand providedbackground data, advice,and encouragement. Many people provided suggestions for surveytechniques andsites to visit,observations of WillowFlycatchers, or assistancein the field,including Dan Airola, Bob Barnes,Ted Beedy, Sam Droge, David Gaines, Mary Halterman, Stan Harris,Rick Hewe.tt, Tom Lambert,William Laudenslayer, Steve Laymon, Ron LeValley,Zev Labinger,Larry Norris,Mike Prather,William Radke, Mike Robbins, LarrySalata, Michael Stafford, Philip Unitt, BradleyValentine, and Jon Winter.The followingindividuals reviewed the manuscriptand made many helpful suggestions: Ted Beedy,Kay Franzfeb,David Gaines, John Gustarson,Steve Laymon, Ron Schlorff, Philip Unitt, and Bradley Valentine.

LITERATURE CITED

Arbib, R. 1979. The Blue List for 1980. Am Birds 33:830-835. Barlow, C. 1900. Some additionsto Van Denburgh'slist of land birdsof Santa Clara Co., California. Condor 2:131-133. Belding,L. 1890. Land birdsof the Pacificdistrict. Occ. Pap. Calif. Acad. Sci. 2. Clay, D.H. 1984. High mountainmeadow restoration, in CaliforniaRiparian Systems (R.E. Warnerand K.M. Hendrix,eds.), pp. 477-481. Univ. Calif.Press, Berkeley. Flett, M.A., and Sanders, S.D., 1987. Ecologyof the Sierra Nevada populationof Willow Flycatchers.Western Birds 18:37-42. Friedmann,H. 1963. Host relationsof the parasiticcowbirds. U.S. Natl. Mus. Bull. 233.

34 WILLOW FLYCATCHER SURVEYS

Gaines,D. 1974. A new lookat the nestingriparian avifauna of the SacramentoValley, California. W. Birds 5:61-80. Gaines, D. 1977. Birds of the Yosemite Sierra. Cal-Syl Press, Oakland. Garrett, K., and Dunn, J. 1981. Birdsof SouthernCalifornia: Status and Distribution. Los Angeles Audubon Soc., Los Angeles. Goldman, E.A. 1908. Summerbirds of the Tulare Lake region. Condor 10:200-205. Grinnell, J., Dixon, J., and Linsdale,J.M. 1930. Vertebratenatural historyof a sec- tion of northern California through Lassen Peak. Univ. Calif. Publ. Zoo[ 10:197-406 Grinnell, J., and Miller, A.H. 1944. The distributionof the birds of California. Pac. Coast Avifauna 27. Grinnell, J., and Storer, T.I. 1924. Animal life in the Yosemite. Univ. Calif. Press, Berkeley. Hanna, W.C. 1928. Notes on the Dwarf Cowbird in southern California. Condor 30:161-162. Harris, J.H., Sanders, S.D. and Flett, M.A. 1987. The status and distribution of the Willow Flycatcher(Empidonax trailriO in the Sierra Nevada. Calif. Dept. of Fish and Game Wildlife Mgt. Branch Admin. Rep. 87-2. King, J.R. 1955. Noteson the life historyof Traill'sFlycatcher {Emp•donax tra#l•O in southeasternWashington. Auk 72:148-173. Linton, C.B. 1908. Notesfrom Buena Vista Lake, May 20 to June 16, 1907. Condor 10:196-198. McCaskie, G., De Benedictis, P., Erickson, R., and Morlan, J. 1979. Birds of Nor- thern California:An AnnotatedField List. GoldenGate AudubonSoc., Berkeley. Phillips,A.R. 1948. Geographicvariation in Empidonaxtraill•i. Auk 65:507-514. Remsen,J.V., Jr. 1978. Birdspecies of specialconcern in California.Calif. Dept. Fish and Game, Nongame Wildlife Invest. Rep. 78-1. Roberson,D. 1985. MontereyBirds. Monterey Peninsula Audubon Soc., Carmel, CA. Rowley, J.S. 1930. Observationson the Dwarf Cowbird. Condor 32:130. Serena, M. 1982. The statusand distributionof the Willow Flycatcher{Empidonax traillii)in selectedportions of the Sierra Nevada, 1982. WildlifeMgt. BranchAd- min. Rep. 82-5, Calif. Dept. Fish and Game. Sharp,B. 1986. Managementguidelines for the WillowFlycatcher. U.S. Fishand Wildlife Service, Portland, OR. Stafford,M.D., and Valentine, B.E. 1985. A preliminaryreport on the biologyof the WillowFlycatcher in the centralSierra Nevada. CaI-Neva Wildlife Trans. pp. 66-77. Stallcup,R., and Greenberg,R. 1974. The nestingseason. Middle Pacific Coast region. Am. Birds 28:943-947. Sumner, L., and Dixon, J.S. 1953. Birdsand Mammals of the Sierra Nevada. Univ. Calif. Press, Berkeley. Tate, J. 1981. The Blue List for 1981. Am. Birds 35:3-10. Taylor, D.M. 1986. Effectsof cattlegrazing on passefinebirds nesting in riparianhabitat. J. Range Mgt. 39:254-258. Taylor, D.M., and Littlefield,C.D. 1987. The influenceof cattlegrazing on Willow Flycatchersand Yellow Warblers.Am. Birds40:1169-1173. Unitt, P. 1984. The birdsof San DiegoCounty. San DiegoSoc. Nat. Hist. Memoir 13.

35 WILLOW FLYCATCHER SURVEYS

Unitt, P. 1987. Empidonaxtrai!!ii extimus: An endangeredsubspecies. W. Birds18: in press. Willett,G. 1912. Birdsof the Pacificslope of southernCalifornia. Pac. Coast Avifauna 7. Willett, G. 1933. A revisedlist of the birdsof southwesternCalifornia. Pac. Coast Avi- fauna 21.

Willow Flycatcher Sketch by Keith Hansen