and Wildlife Research Unit, Holdsworth Natural Resource Center, University of ... Black Rails were first detected in the Colorado River delta in. 1998, at the Ciâ¢nega ... We conducted call-response surveys from March to June 2000 during Yuma.
NOTES
DETECTIONS
OF CALIFORNIA
THE COLORADO
BLACK
RAILS
IN
RIVER DELTA, MEXICO
OSVEL HINOJOSA-HUERTA and WILLIAM W. SHAW, 104 BiologicalSciences East,Schoolof RenewableNaturalResources, Universityof Arizona,Tucson,Arizona 85721
STEPHENDeSTEFANO,U. S. GeologicalSurvey,Massachusetts CooperativeFish and Wildlife ResearchUnit, HoldsworthNatural ResourceCenter, Universityof Massachusetts, Amherst, Massachusetts 01003
Populationsof CaliforniaBlackRails(Laterallusjarnaicensiscoturniculus)have been drasticallyreducedin westernNorth America over the last severaldecades (Repkingand Ohmart 1977, Evenset al. 1991). The CaliforniaBlackRail is listedas threatenedby the CaliforniaDepartmentof Fish and Game and is considereda "speciesof concern"by the U.S. Fishand WildlifeService(www.dfg.ca.gov/endangered/birds.html). In Mexico,the CaliforniaBlackRailislistedasendangered (Diario Oficialde la Federaci6n2000). Currentmanagementof the lowerColoradoRiver, includingthe difficultymaintainingshallowand stablewater levelsat potentially suitablewetlands,is the criticalfactorlimitingthe distribution of BlackRailsinland (Eddiemanet al. 1994). Black Railswere first detectedin the ColoradoRiver delta in 1998, at the Ci•nega de SantaClara (Piestand Campoy 1999), despiterail surveys havingbeen conductedthere in the 1980s and early 1990s (Abarcaet al. 1993, Eddlemanet al. 1994). Evenset al. (1991) speculatedthat BlackRailswere absent fromthesewetlandsbecause of massive habitatdegradation. The purposeof ourstudy was to assessthe presenceor absenceof BlackRailsin the remnantwetlandsof the ColoradoRiverdelta,BajaCaliforniaand Sonora,Mexico. Our surveyswere focusedin the Ci•nega de Santa Clara, at about5800 ha the largestmarshin the delta.Thisweftandlieswithinthe Upper Gulfof Californiaand ColoradoRiverDeltaBiosphereReserve.Other surveyed areaswereHardyRiver,E1 Mayor River,Pescaderos River,Riito Drain, Cucap• Complex,E1Indio Lagoon,E1 Doctor weftands,and EasternDrains (Figure 1). The surveyedwetlandsincluded emergentmarshesfed by agriculturalrunoff and natural springs.Vegetationwas dominatedmostlyby cattail(Typhaclorningensis), with commonreed (Phragrnites australis),bulrush(Scirpusspp.),saltcedar(Tamarix ramosissirna), and saltgrasses (Distichlisspp.)presentalso.Glennet al. (2001) described eachwetland. We conductedcall-responsesurveysfrom March to June 2000 during Yuma ClapperRail(I•allusIongirostrisyumanensis) surveys (Hinojosa-Huerta et al. 2001). After completingthe Yuma ClapperRail surveyprotocol,we playedtapedvocalizationsof CaliforniaBlackRailsfor 2 minutes,followedby a silentperiodof 2 minutes in whichwe recordedall responding individuals. The tape includedtwo typesof calls (starting withkickee-cloo, followedbygruntvocalization) arrangedin a 1-minuteloop. Surveysstartedat sunriseand continuedno later than 1030. Surveystationswere circularplots(30-m radius)locatedat least200 m apartandgroupedintoroutes.We visitedeachstationonceduringthe earlybreedingseason(11-17 March)and again duringlatebreedingseason(18-22 May).We selected the locationof the routesin the Ci•negade SantaClararandomly(16 routes,173 stations,coveringabout9% of the total area of the ci•nega).Other wetlandsconsidered potentialhabitatwere much smaller,and we placedroutesin them nonrandomly to maximizecoverageof these areas(8 routes, 55 stations). 228
Western Birds 32:228-232,
2001
NOTES
Key to Features Colorado River
HardyRiver El MayorRiver Lagunadel lndio Cienegade SantaClam El Doctor
Detections of Black Rails
5
0
5
/•
Streams
•_-•
Wetland areas
10 Kilometers
Wetlands
1- Riparian comdor
n
2-HardyElMayor A 3 - Floodplain 4 - Lagunadel lndio -Eastem Drains 5 - Cienegade Sm•taClara- El Doctor
Figure1. Wetlandareaswhere CaliforniaBlackRailswere detectedin the Colorado Riverdelta,BajaCaliforniaand Sonora,Mexico.
We detecteda totalof 19 BlackRailsat 18 surveystations (3.94 % of the surveyed stations) duringthetwosurveyperiods(Figure2). Mostwerelocatedin theCi•negade SantaClara,wherewedetected10 BlackRailsat ninestations (5.20%of thesurveyed stations) duringearlybreedingseasonandsixat sixstations (3.46% of the surveyed stations) duringlatebreeding season. All of thedetections in thelatebreeding season were>500 m awayfromanydetectionin theearlybreedingseason(Figure2). Cattail wasthe dominantvegetation(>50% of vegetationcover)at all stationswhereBlack Railswere detectedin the ci•nega. Bulrushwas an importantvegetationfeature 229
NOTES
Detections ofblackmils
duringearlybreedingseason
Detections ofblackmils duringlatebreedingseason
Open water
I
Figure2. SurveystationswhereCaliforniaBlackRailsweredetectedin the Ci•nega de Santa Clara, Sonora, Mexico during2000.
(•15% of the vegetationcoverage)at five of thesestations,saltcedaronlyat two. We detectedthree BlackRailsat other wetlandsin the deltaduringMarch (early breedingseason) (presentat 5.45% of thesurveyed stations). One individual wasalong E1Mayor River in a shallow(12-30 cm) agricultural drain dominatedby cattail.A secondBlack Rail was at E1Doctor weftandsin Sonora, which are maintainedby naturalsprings.This area has constantshallowwater throughoutthe year, and its vegetationisdominatedby bulrush.The thirdindividual wasat E1IndioLagoon,Baja California,a recentlyrestoredwetlandsupportedby agriculturaldrainagewater, dominatedby saltcedarbut with substantial cattail.We detectedno BlackRailsat
230
NOTES
HardyRiver,Pescaderos River,RiitoDrain, CucapfiComplex,or EasternDrains.This absencemay be relatedto the dominanceof saltcedarand the lack of a constant sourceof water at thesewetlands(Hinojosa-Huerta2000). CaliforniaBlackRailswere scarceand locatedat only a few sitesin the Colorado River delta during our surveysin 2000. However, these detectionsdocument CaliforniaBlackRailsoccurringin thesewetlandsduringthe breedingseason.These sitesshouldbe monitoredfor changesin the population,with a surveydesignspecific for the subspecies, to avoidpotentialdisruptioncausedby other procedures(e.g., elicitingtapedcallsof YumaClapperRails).An optimumprotocolto surveyCalifornia BlackRailsshouldfollowrecommendations by Spearet al. (1999), althoughfurther researchis needed.The sequenceof callsin the surveytape shouldbe reassessed, as thekickee-doocallmayinterferewiththegruntvocalization (M. Legarepers.comm.). The subspecies shouldbe includedin managementplansfor the biospherereserve, with specificpracticesto enhanceor restoreBlackRail habitat.Our resultsindicate thatthereispotentialin agricultural drainagewaterandremnantwetlandsin the delta for the conservationof the subspecies. This informationshouldbe consideredin the development of conservation andrecoveryplansfor inlandpopulations. This researchwas funded by the U.S. Fish and Wildlife Service, Region 2, (agreementnumber1448-20181-98-G942), throughthe ArizonaCooperativeFish andWildlifeResearchUnit. We thankLin Piest,Jos• Campoy,andMarthaRomfinfor their continuoushelp throughoutthe project. Jules Evens, Robert A. Hamilton, MichaelLegare, and Philip Unitt made helpfulcommentson an earlierdraft.
LITERATURE
CITED
Abarca, F. J., Ingraldi,M. F., and Varela-Romero,A. 1993. Observationson the desertpupfish(Cyprinodonmacularius),YumaClapperRail(Ralluslongirostris yumanensis),and shorebirdcommunitiesin the Ci•nega de Santa Clara, Sonora, Mexico. Nongameand EndangeredWildlifeProgramTech. Rep., Ariz. Game and FishDept., 2221 WestGreenwayRoad,Phoenix,AZ 85023-4312. Diario Oficial de la Federaci6n. 2000.
PROY-NOM-059-ECOL-2000
16/OCT/
2000 Protecci6nambiental--Especies de flora y faunasilvestres de M•xico.-Categoriasde riesgoy especificaciones para suinclusi6n,exclusi6no cambio.-Listade especiesen riesgo.Secretariade Gobernaci6n,M•xico, D.F. Eddieman,W. R., Flores,R. E., and Legare,M. L. 1994. BlackRail (Laterallus jamaicensis),in The Birdsof NorthAmerica(A. PooleandE Gill, eds.),no 123. Acad. Nat. Sci., Philadelphia. Evens,J. G., Page, G. W., Laymon,S. A., and Stallcup,R. W. 1991. Distribution, relative abundance, and status of the California Black Rail in western North America.
Condor 93:952-966.
Flores, R. E., and Eddieman,W. R. 1995. California Black Rail use of habitat in southwestern Arizona.J. WildlifeMgmt. 59:357-363. Glenn, E. P., Zamora-Arroyo,F., Nagler,P. L., Briggs,M., Shaw, W., and Flessa,K. 2001. Ecologyand conservation biologyof the ColoradoRiverdelta,Mexico.J. Arid Env. 49:5-15.
Hinojosa-Huerta,O. 2000. Distribution,abundance,and habitat use of the Yuma Clapper Rail (Rallus longirostrisyurnanensis)in the ColoradoRiver delta, Mexico. M.S. thesis,Univ. of Ariz., Tucson. Hinojosa-Huerta,O., DeStefano,S., and Shaw, W. 2001. Abundanceand distribution of the YumaClapperRail (Ralluslongirostrisyumanensis)in the Colorado Riverdelta, Mexico.J. Arid Env. 49:171-182. 231
NOTES
Piest,L., andCampoy,J. 1999. Reportof YumaClapperRailsurveys at the Ci•nega de Santa Clara, Sonora, 1998. Ariz. Game and FishDept., Yuma Regional Office,9140 E. County101/2St., Yuma,AZ 85365.
Repking,C. F., and Ohmart,R. D. 1977. Distribution anddensityof BlackRail populations alongthe lowerColoradoRiver.Condor79:486-489. Spear,L. B., Terrill,S. B., Lenihan,C., andDelevoryas, P. 1999. Effectsof temporal andenvironmental factorson the probabilityof detectingCaliforniaBlackRails. J. Field Ornithol. 70:465-480.
Accepted27 September2001
Black Rail
232
Sketch by Tim Manolis
