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Home , Belmont Slough, Mowry Slough, Tolay Creek

STATUS OF THE BLACK RAIL IN CENTRAL

TIM MANOLIS, EPO Biology,Universi• of Colorado,Boulder, Colorado 80309

The CaliforniaBlack Rail (Laterallusjamaicensis coturniculus) isclassified "Rare"by the CaliforniaFish and GameCommission, but thissecretive rail's statusalwavs has been difficult to assess.Wilbur (1974) and Gill (1977)concluded that recordsof singingbirds in springand immatures in late summerindicated probable breeding by BlackRails in the'San FranciscoBav area. Within recentyears, calling Black Rails were located in springand summerin Solano,Napa and SanJoaquin counties (Jurek 1976,Department of Fishand Game files). These findings prompted this study,which began 25 March 1977and concludedon 14July 1977.Its purposewas to clarify.the statusof the speciesin northernand central Californiaand attemptto identifyits habitatrequirements. METHODS Census sites were selected based on the historical distribution of BlackRails in centralCalifornia. An attemptwas also made to censusas widea varietyof differentmarsh types as possibl& Censusing involved walking through or adjacentto suspectedBlack Rail habitat while playingtape-recorded Black Rail callsin an attemptto elicitresponses from birds on territories.Calls were broadcastusing a cassettetape recorderconnected to a 15 watt powerhorn. A standardcensus tape, with alternating"grr" and"kicokic-kerr"call sequences(Repking and Ohmart1977) separated by 1 minutepauses, was used most frequently, particularlyduring the firstvisit to a site.Information recorded for each sitecensused included: date, time, weather, habitat description, number and kindsof responsesand otherrelevant data. The locationsof calling birds were plotted on photocopiesof U.S. GeologicalSurvey topo- graphicmaps. A numberof visitsto representativemarshes around San FranciscoBay were made during peakhigh tide periodsin lateMay and June to view the effectsof thesetides on the habitat. DISTRIBUTI ON At least32 BlackRails were heard during this survey in 14localities in thenorthern area and the delta of theSacramento-San Joaquinriver system.Only one BlackRail wasseen. Twenty-two of the birdsfound in thisarea were in marshesbordering or the riversystems (Napa and Petaluma)that emptyinto SanPablo Bay from the north.No BlackRails were found in marshesbordering the Pacific Ocean, or in San FranciscoBay south of the Richmond-SanRafael Bridge(Figure 1). SevenBlack Rails were heardin a censusof marshes borderingMorro Bay,San Luis ObispoCounty, on 14 and 15 April. Western Birds 9:151-158, 1978 151 BLACK RAIL

The followingarea-by-area review of thepast and present distribution of BlackRails in northernand centralCalifornia is basedprimarily on the resultsof this study and the followingsources: Wilbur (1974); specimensin the Museumof VertebrateZoology (MVZ), Berkeley,and

•% {• • 21 I •rt• - ' ' •

0•_•..•.__•0 29 MILES •3•36 310 ,o•5•'O 2,o • KILOMETERS 35

Figure 1. Locationswhere Black Rails were heard (numbersin solid circles)and searchedfor but not found (uncirclednumbers) in the San FranciscoBay area, California,during spring and summer 1977. Broken circles indicate where birds were heard by others in 1976 and 1977 (see text). Locationsare: 1--Kehoe Marsh; 2 = Inverness; 3 = Olema Marsh; 4 = San Antonio Creek mouth; 5 = Black Point; 6 = ; 7 = Midshipman'sPt., Tubbs I.; 8 = north shoreSan Pablo Bay; 9 = SouthSlough; 10 = Napa Slough;11 = Fly Bay; 12 = FaganSlough; 13: China Slough;14--South Sloughmouth; 15= White Slough;16--Dutchman's Slough; 17= SouthamptonBay; 18-- Cordelia(vicinity); 19 = PeytoniaSlough; 20 = Duck Slough;21 =Joice I.; 22 = GrizzleyI.; 23 = Mallard I.; 24 = Port Chicago(vicinity); 25=Martinez Marina; 26=Pinole; 27=Pinole Pt.; 28=: 29 = CoyoteHills RegionalPark; 30 = Ideal CementMarsh; 31 = DumbartonPt.; 32= ; 33 = Albrae Slough; 34= Triangle Marsh; 35 = Palo Alto Baylands;36 = GrecoI.; 37 = CorkscrewSlough, Bair I.. 152 BLACK RAIL

the CaliforniaAcademy of Sciences(CAS), San Francisco; Audubon Field Notes(AFN) and AmericanBirds (AB); and informationobtained by Departmentof Fishand Gamepersonnel and compiled in the Depart- ment's CaliforniaBlack Rail file in Sacramento(DFG.)

WESTERNMARIN COUNTY. BlackRails were frequently collected during high floodtides in thefall and winter (September through February) in saltmarshes on the edgeof near Marshall and Point Reyes Station from 1897 to at least 1940 (Wilbur 1974,MVZ, CAS),and onewas observed during a hightide at the headof the bay on 5 February1974 (DFG). From 1965to 1967,one pair inhabiteda small, brackishmarsh near Invernessand apparentlybred, as chickswere reportedseen one summer(AFN 21:73, 1967;Gerald Brady pers. comm.). Salt marshes around TomalesBay, not checkedin this study,may yet harbornesting Black Rails. Black Rails have been found at Kehoe Marsh and Olema Marsh between October and Feb- ruaryand havebeen heard calling at OlemaMarsh in April andMay in recentyears (AB 29:903,1975;DFG). In thisstudy, one was calling at the upperend of Olema Marshon 5 April 1977,and it is possiblethat they breed at thislocation. A BlackRail collectedat Elk Valley on 13 March 1945 (MVZ) was probablya migrant or non- breedingwanderer. MARSHES.No recordsfrom thesemarshes existed prior to this study.Six birdswere heard at the mouth of SanAntonio Creek,Marin and Sonomacounties on 4 May 1977, indicatingthat a potentiallylarge, previously unsuspectedpopulation inhabits these marshes. NAPARIVER MARSHES. There appear to be norecords for thesemarshes prior to 1976;tworesponded to tapedcalls near Fagan Slough, Napa County, on 14Julyof thatyear (DFG). In thisstudy, Black Rails responded to tapedcalls at fivelocations in the NapaMarshes: a minimumof threebirds along Tolay Creek, Sonoma County; onealong Napa Slough, Napa County; one along South Slough and two to threealong theNapa River at the mouth of South Slough, Solano County; and one at the mouth of WhiteSlough, Solano County. A substantialbreeding population is indicated. SAN PABLO BAY MARSHES. Prior to the 1970s, there seem to have been no recordsof BlackRails around this bay. Five were seen at themouth of GallinasCreek, MarinCounty, on 11 December1973; one was seen there on 7January1974, and one was seen at Pinole, Contra Costa County, on 19 November 1975 (DFG). An abandonednest, reportedly of this species,was found at Pinolein fall 1976 (AB 31:1184,1977). A singlebird was seen or heardat Midshipman'sPoint, , SonomaCounty, on 14 and26 February,21 July and 10September 1977 (Gail Scott andJack Arnold pers. comm.); two birds were found there 19 May 1978(AB 32:1050, 1978);and a callingbird was at Black Point, Marin County, on 24 May 1977 (Robert M. Stewartpers. comm.). During this study, at leastthree singing birds were heard in a marshat Pinole,Contra Costa County; a singlebird was heard at PinolePoint, Contra CostaCounty; and at leastthree birds were heard in a sectionof theextensive marsh borderingthe northeastshore of SanPablo Bay in SolanoCounty. Much of the remainingmarsh fringing San Pablo Bay appears suitable for BlackRails. SOUTHAMPTON BAY MARSH. Two were observedin this marshon 2 April 1958(AFN 12:383,1958) and therehave been numerous sightings during high win- ter tidessince 1973 (AB regional files, DFG). Onewas heard in the marshon 22 May 1975 (Roberson1975) and singlecalling birds were heardon 2 and 26 June 1976 (DFG).During frequent censusing in summer1977, as many as three birds were call- ingat one time, and four pairs were estimated present (Frank Beyer pers. comm.). One foundin nearbyBenicia, Solano County, on 18July1941 (Stoner 1945)was probably a migrantor post-breedingwanderer. 153 BLACK RAIL

SUISUN MARSHES and NORTHERN CONTRA COSTA COUNTY. Black Rails were collectedin the SuisunMarshes, Solano County, on 11 September1913, 19 October 1910 and 15 January 1911 (MVZ). Individualswere reportedseen on 13 December1975 and 29 December1976 near Cutoff Slough, and 28 December1974 nearSuisun Slough, both in SolanoCounty •e•de Frank Beyer pers. comm.). In Contra CostaCounty there is an old winterrecord for Martinez(Grinnell and Wythe 1927) and there are recent(1975-76) winter sightings,probably valid, near Port Chicago (DFG). During this survey,one BlackRail was heard at PeytoniaSlough, Solano County, on 5 July 1977 and two or three birds were heard and one was seenon ,Contra Costa County, on 2July 1977.An immatureBlack Rail was founddead near Peytonia Slough on 11August 1977 (DFG). Three calling Black Rails were in a marshbordering the Big Breaknear Oakley,Contra Costa County, on 18 May 1978(AB 32:1050,1978). Black Rails apparently breed in the limitedsuitable habitatremaining in this area. SAN FRANCISCO BAY. BlackRails were frequently collected in fall and winter (Octoberthrough February) at ,Bay Farm Island and Newark,Alameda County;Alviso and PaloAlto, SantaClara County;and RedwoodCity, SanMateo County,between 1892 and 1913(Wilbur 1974,CAS, MVZ). Sightrecords in theyears sincehave been in approximatelythe sameareas in the samemonths (AB regional files, DFG). There is one definitespecimen (CAS 208), and anotherpossibly mislabeled(bearing two conflictingspecimen labels, CAS 207 and 12938),for Palo Alto on 24 May 1930. One wasseen along , San Mateo County,in August1972 (Barry Sauppe pers. comm.) and anotherwas seen on 7 August1958 at DumbartonPoint, Alameda County (AB regionalfiles). Wheelock (1916) claimed, without presentingevidence, that Black Rails nestedat Alviso.A nest with eggs collectednear Newark in 1911is the firstproof of nestingby BlackRails in northern California(Kiff 1978).Black Rails were not found in marshesaround San Francisco Bayproper during this study, and the lackof suitablehabitat (high marsh) indicates thatthey may no longernest around this bay. There are two specimens from northSan FranciscoBay, both in Marin County:one found dead near Manzanita on 11August 1929(MVZ) and one from Kentfieldon 8 February1932 (CAS). High marsh habitat in thisarea hasbeen reduced greatly since the time of theserecords. Of 12 recordsof BlackRails away from tidal marshesin the SanFrancisco Bay region,6 arefrom San Francisco, 2 are from upland sites in AlamedaCounty and 4 are from the FarallonIslands (Wilbur 1974, CAS and MVZ). Sixof themainland records arefor theperiod August through October and suggest migration or post-breeding wandering. CENTRAL VALLEY. Belding (1879) vaguelyrecollected possibly collecting a BlackRail near Stockton,San Joaquin County,in the mid 19th century.One was found dead nearthere on 26 August1959 (Arnold1960). Department of Fishand Gamepersonnel discovered Black Rails calling in summer1974 in a marshnear Lodi, sanJoaquin County, and threewere heard there during this study. Although suitable habitatis fairlylimited there now, Black Rails should be expectedelsewhere in the Sacramento-SanJoaquin Delta where high, tidal marsh occurs. One otherdefinite recordexists for the CentralValley; a bird, mostlikely a.vagrant, was found dead at GrayLodge Wildlife ManagementArea, Butte County, in March 1962(AFN 23:516, 1969). Sightingshave been reportedfrom Colusa(AB regionalfiles) and Yolo (Kimball1974) counties, but breeding season surveys at SacramentoNational Wildlife Refuge,Glenn County,at Gray Lodge,and at Los BanosWildlife Area, Merced County,have yielded negative results in recentyears (DFG). MONTEREY BAY. Black Railswere collectedat SantaCruz, SantaCruz County, on 19July 1930and 25 August1941 (MVZ), and onewas found dead there in Sep- tember 1903 (Emerson1904). One was found dead in PacificGrove, Monterey

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County,on 29 September1967 (VernalYadon pers. comm.).These are probably recordsof post-breedingwanderers or migrants. MORRO BAY.A BlackRail wascollected in Morro Bay,San Luis Obispo County, on22 April 1961(AFN 15:439,1961); one was found dead there on 18December 1972 (AryanRoest pers. comm.); and singleswere seenthere 30 November1968 (AFN 23:107,1969) and 2January 1969 (AFN 23:521, 1969). Seven Black Rails were heard in marshesaround Morro Bayduring this study,and the evidencepoints to a resident population.

HABITAT Grinnelland Miller (1944) describedthe habitatpreferred by Black Railsas "chieflytidal salt marshes,where associatedcharacteristically with heavygrowths ofpickleweed (Salicornia). But also occurs in brackish and freshwatermarshes..." This study confirmedtheir description. Thirty-sevenof the 39 BlackRails found werein marshesdominated by eitherSalicorniavirginica or bulrush(Scirpus spp.), and 7 of the 13 birdsin Scirpus-dominatedmarshes were in or near parts of the marsh where Salicorniavirginica was present and fairly abundant.The typesof Scirpus frequentedby Black Rails are low-growing forms (e.g., S. americanus at the Big Break,Contra CostaCounty; David Gainespers. comm.) found in the higherparts of marshes.The bird at Pe,vtoniaSlough was in an area wherematted salt grass (Distichlis spicata) merged with a standof cattails (Typhasp.) and Scirpus, and the bird in OlemaMarsh was calling from a standofTypha. The frequentassociation of BlackRails with pickleweed is probablya reflectionof their preferencefor high marshes,but the importanceof pickleweed,and possiblysalt grass, as sources of nesting materials and substrates remains to be examined. Exceptfor thebird at OlemaMarsh, all BlackRails found in thisstudy were in tidal marshes. Areas within these marshes where Black Rails were heard are near the upper limits of tidal flooding.No BlackRails re- spondedin salt or brackishmarshes that are no longer under tidal influence(e.g., Figure 1: sites 18, 20, 21 in part,22, 29),or in lowmarshes that are dominatedby Scirpusspp. (sites11, 21 in part, 34) or Salicornia virginicaand/orSpartinaJbliosa (sites 28, 30, 31, 32, 33, 35, 36, 37) but are frequentlycovered by high tides. Postand Enders(1969) hypothesizedthat Black Rails find tidal marshesmore attractivethan diked marsheswith similar vegetation possiblybecause of higherfood resource levels in tidalmarshes. Little is knownabout BlackRail food habits(Wilbur 1974)but apparentlythey feedon arthropods(Huey 1916).The varietyand abundance of arthro- podsin a marshare probably affected considerably by thefrequency and magnitudeof waterlevel fluctuations in themarsh. Black Rails found in thisstudy were often in theimmediate vicinity of tidalsloughs, indicating a concentrationof activityin thispart of themarsh. These sloughs teem with invertebrates,a featurenoticeably lacking in dikedmarshes. 155 BLACK RAIL

In a surveyof marshesalong the lower Colorado River, Repking and Ohmart( 1977)found a definiterelationship, similar to thatobserved in this study,between Black Rail distributionand marshelevation. They found BlackRails in high, shallowwater marsheswith litde annual and/or daily fluctuationsin water level, but not in low, deep water narshes or marshes with considerable fluctuations in water level. Ingersoll(1909), Huey ( 1916)and Stephens( 1919) found evidenceof profoundeffects by hightides on BlackRail populations,and Grinnell andMiller (1944)felt that the "most important hazards to existence[of BlackRails] on saltmarshes appear to be extrahigh tides." The factthat BlackRails were not foundaround San Francisco Bay properin thisstudy may reflect the lackof highmarsh habitat around thisbay. Many areas of saltmarsh in southSan Francisco Bay have sub- sidedin the pastquarter-century because of humanremoval of ground water(Conradson 1966) and large tracts of low-lyingmarsh in thisarea abutabruptly against salt pond dikes and other human-made structures, insteadof graduallymerging into uplandhabitats as they formerly did. Nearly all the remainingsalt marsh in the southbay is completely coveredby peak high tides, and often extensivelyflooded by even moderatelyhigh tides Qeu/e San Francisco Bay personnel,pers. obs.). Similarly, in areassuch as the Suisun Marshes and the Sacramento-SanJoaquin Delta, where dikes have reclaimed much tidalmarshland and left onlynarrow borders of deepwater tidal marsh, BlackRails were probablymuch more commonin the pastthan at present.Suitable high marsh vegetation for nesting,then, appears to be the most limiting factorin determiningthe currentdistribution of breedingBlack Rails in the SanFrancisco Bay area. Thisstudy was conducted during a severedrought in northernCali- fornia.A majoreffect of the droughtwas an increasein salinitylevels throughoutthe Sacramento-SanJoaquin Delta and SanFrancisco Bay area.The salinityof marshesin which BlackRails were heardwas not measured,but it no doubtvaried considerably from very low (Olema Marshand the marshnear Lodi) to ratherhigh (San Pablo Bay) levels. Salinitydid not appearto be a factoraffecting the distributionof Black Rails in the area. This surveyfound BlackRails in a number of marshesin the San FranciscoBay area, but many bay marshesthat may have summer populationsof BlackRails have yet to be checkedfor thisspecies. Effec- tive managementprograms to preservesuitable nesting habitat for CaliforniaBlack Rails require more surveywork and a betterunder- standingof the interrelationshipsbetween this speciesand other elements,living and non-living,of the marshecosystem.

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ACKNOWLEDGMENTS This studywas supportedby the U.S. Fish and Wildlife Service throughthe EndangeredWildlife Program, Nongame Wildlife Investi- gations,California Department of Fishand Game. RonJurek provided the groundworkand assistedin programmingthe study;Charles Repkingprovided the tapedcalls used; and LaurenceBinford, Frank Beyer,Jack Booth, Jerry Cawthon, Dick Erickson,Kent Fickett, Don Grider, SusanneLuther, Jim Michaels,Cathy Osugi,Bob Personius, AryanRoest, Glen Rollins and R. M. Winemanwere of indispensable help.Jeanne Conry and Alan Craig providedhelpful comments on draftsof thispaper. My specialthanks to thoseI failedto mentionbut whohelped in anyway, and to HowardLeach, California Fish and Game NongameWildlife Investigations, for allowingme to workon suchan enjoyableproject.

LITERATURE CITED Arnold,J. R. 1960.Black Rail in SanJoaquin Valley of California.Condor 62:405. Belding,L. 1879.A partiallist of thebirds of centralCalifornia. Proc. U.S. Natl.Mus. 1:388-449. Conradson,D. R. 1966. Exploringour baylands.The Palo Alto Chamberof Commerce,Palo Alto. 60 pp. Emerson,W. O. 1904. Destructionof birds by wires.Condor 6:37-38. Gill, R. Jr. 1977.Breeding avifauna of the SouthSan Francisco Bay estuary. West. Birds 8:1-12. Grinnell,J.and M. W.Wythe. 1927. Directory of the bird-life of the San Francisco Bay region. Pac. CoastAvif. 18. Grinnell,J. and A. H. Miller. 1944.The distributionof the birdsof California.Pac. Coast Avif. 27. Huey, L. M. 1916.The Farallonrails of SanDiego County. Condor 18:58-62. Ingersoll,A.M. 1909. The only known breedingground of Creciscuscoturniculus. Condor 11:123-127. Jurek,R. M. 1976.California Black Rail survey.Proj. No. W-54-R-8,JobI-1.3. Job ProgressReport. California Dept. Fishand Game,Nongame Wildl. Invest.3 pp. Kiff, L. 1978.Probable Black Rail nestingrecord for AlamedaCounty, California. West. Birds 9: 169-170. Kimball, B. 1974. Seasonalobservations. Observer 24:40. Post,W. and F. Enders. 1969. Reappearanceof the Black Rail on . Kingbird19:189-191. Repking,C. F. and R. D. Ohmart. 1977. Distributionand densi• of BlackRail populationsalong the lower ColoradoRiver. Condor 79:486-489. Roberson,D. 1975. May andJune observations.Gull 57:88. Stephens,F. 1919. Random notes.Condor 21:123-124. Stoner, E. A. 1945. The Black Rail at Benicia, California. Condor 47:81. Wheelock,I. G. 1916. Birdsof California.A. C. McClurg and Co., Chicago. Wilbur, S. R. 1974. The literature of the California Black Rail. U.S. Fish Wildl. Serv. Spec.Sci. Rcp. Wildl. 179. 17 pp.

Accepted25 October1978 157 Sketchby Tim Manolis

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