WESTERN BIRDS
Volume 12, Number 1, 1981
THE BREEDING
SNOWY
PLOVER
STATUS OF THE
IN CALIFORNIA
GARY W. PAGE and LYNNE E. STENZEL, Editors, Point Reyes Bird Observatory,
4990 ShorelineHighway, StinsonBeach, California94970
The westernrace of the Snowy Plover (Charadriusalexandrinusnioosus)
breeds on the Pacific coast from southern Washington to southern Baja
California, inland in Oregon, California, Nevada, Utah, Colorado, New
Mexico, Kansas, Oklahoma and Texas, and along the coastsof Texas and
northeasternMexico (AOU 1957). For many yearsornithologists
believed
that the number of Snowy Plovers breeding along the Pacific coast was
decliningas developmentdestroyedsuitablehabitat.In May, June and July,
from 1977 to 1980, Point Reyes Bird Observatory(PRBO) biologistsand
volunteers conducted surveys of potential breeding habitat throughout
Californiato gather informationon the distributionand abundanceof Snowy
Plovers.Thispapersummarizes
the resultsof thosesurveysand the available
data on the species'past abundanceand distribution.We attempt to define
suitablebreedinghabitatand to describethe effectsof human activitieson it.
Detailedstudiesof markedbirdsundertakenby John and Jane Warriner at
PajaroDuneson MontereyBay have been very helpfulin interpretingthe
surveyresults.Their informationon migrationperiods,mid-breedingseason
movements and the detection rate of birds on censuses is summarized in this
paper. Detailed information on the occurrenceof birds at specificsites is
available in a report (Page and Stenzel 1979) on file with the California
Department of Fish and Game in Sacramento. If readers have information
indicatinggreaterbreedingnumbersor know of breedingsitesnot mentioned
here, we and the Departmentof Fishand Game encouragethemto contactus.
METHODS
The breedingsurveycoveredthe coastbetweenthe Golden Gate and the
Oregon border in 1977, the remainder of the Californiacoastand interiorin
1978, and the ChannelIslandsfrom 1978 to 1980. A listof all sitessurveyed
on the mainlandcan be derivedfrom Appendices1 and 2.
SusanPeasleeand Gary Page,with occasional
helpfrom others,covered
the coastfrom the Golden Gate to the Oregonborderbetween16 May and
11 June 1977. From USGS topographicalmapsthey locatedbeachesapWestern Birds 12:1-40,
1981
1
SNOWY PLOVER BREEDING STATUS
pearingto have sand or pebblehabitatabove the high water mark. They
surveyedthesebeaches,startingin Marin Countyand proceedingnorthto
Del NorteCounty.Additionalcensuses
to recheckcertainbeachesduringthe
last3 daysweretakenin HumboldtCounty.On everybeachall openhabitat
wascheckedand heavilyvegetatedor litteredareaswere sampled.Physical
characteristics,
vegetation, debriscover, evidence of nest predators, and
level of human disturbancewere recorded. The age and sex of Snowy
Ploverswere determinedwhen possible.Adult maleswere distinguished
by
their blackforehead,cheekand shoulderplumage;somemalesalsohad a
distinctive
rustycapwhichfemaleslacked.Adultfemaleswererecognized
by
brownerfeatheringin theseregions,and juvenilesby distinctive
pale edgings
on wingcoverts.We attemptedto find the nestsof all birdswhosebehavior
suggestedthey mightbe incubating.Descriptions
of each nestincludedthe
presenceor absenceof nearbyobjects,substratetype, distancefrom water
and opennessof habitatwithin a 10 m radius. Broods of chicksalso were
locatedand the sizeand numberof youngrecorded.
In someareasit was impossibleto detectall plovers,and estimateswere
madeto partiallycorrectfor missedbirds.We usedfour methodsto estimate
the numberof breedingpairs:1) totaladultsdividedby 2; 2) totalpairsseen;
3) total singlefemalesor maleswith nestsor broods;and 4) total pairsseen
plussingleadultswith nestsor broods.For eachareathe methodresultingin
the highestnumberof pairswas used.
From 8 May to 26 June and on 9 July 1978 Lynne Stenzeland Susan
Peasleemadecensuses
or spotchecksof beaches,lagoons,rivermouthsand
bars, bay shores,salt pans and saltworksalong the coastbetweenBorder
Field, San Diego County, and the Golden Gate. Suitableareasfor censuses
were selectedfrom USGS topographicalmaps, referencesin the literature,
and many unpublishedfield observations.Only in Los Angeles County,
where we assumedbeach groomingactivitiesprecludedthe possiblityof
nesting,did we knowinglyexcludesomesandbeachfrom our survey.Our
findingson the similarlygroomedbeachesof OrangeCountyand a description of how groomingmakesplover nestingvirtuallyimpossibleare reported
in the results.Althoughthe surveyprogressed
from southto north,therewas
someback-tracking
or skippingahead so that censusescould be made at
heavilyusedareason weekdaysand at restrictedaccessareason weekends.
Survey methodswere similarto those used in 1977 except that nest
descriptionswere more detailed and included information on the
topographicrelief within 1 and 10 m. A searchwas made for nestsand
broodsto establishevidence of breedingin each locality,but to minimize
surveytime and disturbance,particularlyin Least Tern ($terna albifrons)
nestingareas, no attempt was made to locate all nests.
The interiorsurveylastedfrom 26 Apriluntil 13 July 1978. PhilipHendersonfirstcheckedareasin the San JoaquinValleyand aroundthe SaltonSea.
He thengenerallymovednorthward,workingaloneuntil1 JunewhenGary
Pagejoinedhim in Inyo County.Potentialbreedingareaswereselectedfrom
USGS topographicalmaps, from ornithologicalliteratureand from discussionswith personsfamiliarwith the distribution
of Californiabirds.Alkaline
lakesparticularlywere soughtout, but if theselackedstandingwaterthey
were not surveyedbecauseploverswere assumedto be absent.
SNOWY
PLOVER
BREEDING
STATUS
Survey methodsvaried accordingto each area'sphysicalcharacteristics
and accessibility
by car. At eacharea we took manyphotographsand notes
on vegetationand physicalcharacteristics.
We recordedthe age and sex of
ploverswheneverpossiblealthoughsometimesglaring,middaylightingor
the largenumberof ploversencounteredat one time madethistaskimpossible. We attemptedto find some nestsor broodsin each area and described
nestssimilarlyto thoseon the coast.
NancySpearconductedsurveysof the breedingpopulationson four of the
Channel Islands.On 25 and 26 April 1978 she searchedbeacheson San
ClementeIslandand between19 and 21 May 1978, with Hal Spearand Bob
Jackman, beacheson San NicolasIsland. From 13 to 18 July 1979 the
Spearsand Mike Hill coveredmostof San MiguelIsland'sbeaches,and on
22 July Bud Antonelissurveyedfive additionalones.From 4 to 7 June 1980
the Spears surveyedbeacheson the east end of Santa Rosa Island. On all
surveysthey recordedthe numberand locationof all ploversand whenever
possible,their age and sex.
The historical
statusof breedingSnowyPloversthroughoutthe statewas
inferredfrombreedingrecordsin the literature,fromunpublished
fieldnotes,
and from egg and nestcollectionrecordsand summarizedin Appendix1.
Sourcesof unpublished
recordsare listedin Appendix3.
RESULTS
I. CHANNEL
NANCY
ISLANDS
L. SPEAR
Basedon my surveys,at least 130 pairsof Snowy Ploversbreed on San
Nicolas,San Migueland SantaRosaislands(Table1). The speciesalsomay
breedon Santa Cruz Island, althoughthe lack of nestrecordsfrom earlierin
the centurywhenthe islandwasregularlyvisitedby eggcollectors
(Killpers.
comm.), as well as the low numberof wide sandybeaches,doesnot attest
well to the species'presencethere.The remainingislandsprobablyare not
used by breeding plovers. As the following accountsillustrate, habitat
availabilityratherthan human disturbance
appearsto be the majorfactor
limitingbreedingdistributionon the Channel Islands.
San ClernenteIsland. This 34 km long, narrow islandlies 69 km southsouthwest
of PointFermin.Sandybeaches,oncereportedascommonalong
the westand north sides,now existonly on the north;beachareasto the
south,oncereportedlysandy,are now primarilycoveredwith rocks.The
Navy maintainsa smallbaseon the islandand infrequentlyconductslargescalemaneuverscoveringthe islandand usingbeachesas entrypoints.
Snowy Plovers probably do not breed on this island. Howell (1917)
reporteda few birdsin fall 1907, buttherehavebeenno reportsduringthe
breedingseason.I surveyed40% of the coastlineby foot and observedfrom
a distanceanother40%. I foundno SnowyPlovers,nor muchappropriate
breedinghabitat.That habitatwhichdid existisat NorthwestHarbor,a beach
usedfor recreational
purposes
aswellasfor minormilitarymaneuvers.
Island
Foxes(Urocyonlittoralisclementae)and Common Ravens(Coruuscorax)
occurbut I doubtthat their presenceis a major reasonfor the absenceof
plovers.
SNOWY
PLOVER
BREEDING
STATUS
Santa Catalina Island. The 30 km long Santa Catalina Island is rugged,
mountainous
and hasprecipitous
shoreswithfew sandybeaches.It isheavily
used by the public for boatingand other recreation.Although Meadows
(1934) reported Snowy Ploversas common on the beach at Howland's
Landing, it is now generallyagreedthat they do not breed regularlythere
(Jones pers. comm.).
San Nicolas Island. San Nicolas, the Channel Island farthest from
the mainland, lies 98 km south-southwest
of Point Mugu. It is 13 km long
and 5 km wide. The Navy maintainsa basewith an airstripon the northeast
side. Sandy beachesare common along the perimeter and are backedby
dunes, bluffsand sandstonerock.
Snowy Plovers are regular breeders;evidence dates back to the early
1900s when Willett (1912) found them "fairlycommon"and Howell (1917)
reportedtheirbreeding.Reportsfrom 1976 and 1977 indicatedbreedingac-
tivity with Jones (pets.comm.)describingthem as "a widespreadbreeder
every year," and Schroeder (pets. comm.) reporting them to be common
and breedingin 1977 on the five beacheshe surveyedmonthlyfor birdcarcasses.On my 1978 surveyof 24 beaches,133 adult, 2 juvenileand 9 chick
(4 broods)Snowy Ploverswere found. Adding estimatesfor three additional
beachessurveyedby telescopefrom nearby bluffs, I estimate74 breeding
pairs (Table 1). No scrapesor nestswere found mainlybecausethere waslitfie time to look for them.
Althoughploverswere found around all the island,the heaviestconcentrationsoccurredon the northwestedge at Red Eye Beach, on the sandspitat
the eastend, and from just west of Dutch Harbor to Daytona Beach. Competitionfor spacemay occuron southwestsidebeaches,which supportseal
Table 1. Numberof SnowyPloverpairson the ChannelIslands.Sourcesare discussed
in the text.
ESTIMATED
ISLAND
PAIRS
From 1978 Survey
San Clemente
0
San Nicolas
74
From 1979 Survey
San Miguel
From 1980 Survey
35
Santa Rosa
21
Estimates Based on Other Sources
Santa Catalina
0
Santa Barbara
0
Anacapa
Santa Cruz
TOTAL
4
OBSERVED
0
--
130
SNOWY
PLOVER
BREEDING
STATUS
and sea lion rookeries.Althougha few adultsand chickswere reportedon
oneof thesebeachesin 1977, we foundnoneduringthe 1978 survey.Island
Foxes,CommonRavensand fetal catsare presentbut not abundant,suggestinga low threatfrom predators.
The birdsdid not appearto be disturbedby humanactivity,but increased
navaloperations,withan expectedincreasein personnelare proposedfor the
nearfuture.Thisalmostcertainlywillincreasebeachuseandbreedingactivity may be affected.
Santa Barbaraand AnacapaIslands.Santa Barbaraand Anacapaare the
smallestislands.Their shoresare bold and almostperpendicular.As there
are no beaches,Snowy Ploverscannot breed on either island (pers. obs.,
Jones pers. comm.).
Santa Cruz Island.Santa Cruz, the largestChannelIsland,is 34 km long
and is located 27 km west-southwest of Port Hueneme. Beaches around the
islandare interspersed
with steepcliffsrisingdirectlyfrom the water; the
largerbeachesare on the eastand westends.A dozenanchorages
around
the islandare heavilyused duringlate springand summerby cruising
yachtsmen.Althoughaccessis by permit only and restrictedto hiking,
beachesnear popularanchorages
probablyreceiveheavyuse, whichcould
deterSnowy Ploversfrom nesting.
The Snowy Plover'sbreedingstatuson Santa Cruz is uncertain.Howell
(1917) reportedthe birdsto be "fairlycommonduringthe latefallof 1907."
Observers
conductingbird carcasscensuses
founda few SnowyPloversusingeightbeachesduringAugust1976 andfromJanuaryto March1977, but
none from April to June, suggesting
the specieswintersbut doesnot breed
on the island.
SantaRosaIsland.Lying39 km southwestof GoletaPoint, SantaRosais
24 km long and 16 km wide. Precipitousrocky shorelinesconstitutethe
northand southsides,whilethe eastand westcoastsconsistof manysandy
beaches.
At least43 Snowy Ploversbreed there. BetweenMarch and September,
1968 to 1976, from 2 to 40 birds have been found on the island (Collins
pers. comm.). Duringmy survey,whichincludedall beachbetweenSkunk
and Eastpointson the eastend of the island,43 adultand 2 juvenileSnowy
Ploverswerefound. It is highlyprobablethat a similarnumberof ploversoccur on unsurveyedbeachesbetween Cluster and Sandy points on the
southwest side of the island.
Santa Rosa'sbeachesare privatelyowned and receivelittlehuman disturbance. A potentialpredatoron plover eggsand chicksis the Island Fox,
whose tracks were found on most beaches.
San l•iguel Island. The westernmost island of the northern group, San
Miguellies37 km southeastof PointConception.The shoresvaryfrombold,
rockycliffsto stretches
of beach.Willett(1912) reportedSnowyPloversthere
in summer. Recentobserversreportedsightingsin May and June 1977 and
believedthe speciesprobablybred in restrictedlocalitiesevery year (jones,
Collinsand Kelly pers. comm.).
Duringour 1979 survey84 adult, 8 juvenileand 4 chickSnowy Plovers•
were found. As thisspeciesbeginsautumnmigrationin July, all birdsseen
werenot necessarily
breedingon San Miguel.Mostbirdswerefoundsinglyor
SNOWY
PLOVER
BREEDING
STATUS
in smallgroupsbutone flockof 10 mayhavebeenmigrantsand hencehave
not been includedin the estimatedtotal of 35 breedingpairs (Table 1).
Except for Cuyler Harbor, beacheson San Miguel suffer little human
disturbance;howeverplansare currentlybeingconsideredto open the island
to increasedpublicuse. IslandFoxesare abundantand may destroysome
nests.We found fairly fresh fox trackson mostbeaches.
II.
MAINLAND
COAST
LYNNE E. STENZEL, SUSAN C. PEASLEE and GARY W. PAGE
Survey CensusResults
Duringthe 1977 and 1978 breedingsurveys954 adults,representingan
estimated498 pairs of Snowy Plovers,were found on the mainlandcoast
(Table2). They occurredin 45 locationsand in all but4 eithernestsor chicks
were found. In the remainingfour areas, all in San Diego County, another
observerfound nestsor chickseitherlaterin the seasonor the followingyear.
Breedingploverswere locatedin all coastalcountiesexceptLos Angelesand
San Francisco.Accountsfor each county,startingat the Mexicanand ending
at the Oregon border, follow.
SAN DIEGO COUNTY, with 26% of the estimatedpairs on the coast,
supportedthe mostbirds.We found breedingploverson spitsand alkaliflats
at the TijuanaRiver mouth, on saltevaporators,bay fill and beachesaround
San DiegoBay, on the northernlagoons,and on spitsand alkaliflatsat the
Santa MargaritaRiver mouth (Table 2). When surveyed, BatiquitosLagoon,
flooded from winter and springrains, had only a narrow ring of potential
habitat.Later, droppingwaterlevelsexposedadditionalsuitablenestingflats.
A countof 39 adultsmade by otherslaterin 1978 and, in otherrecentyears,
of 75 adults (Appendix 1), probably are more representativeof plover
numbersat Batiquitosthan our count of 6 adults. Althoughwe found no
positiveevidenceof breedingat the SweetwaterRiver mouth, SilverStrand
bay shoreor BatiquitosLagoon, nestingat thesesiteswasconfirmedlaterin
1978 by Parkeraswell as by severalobservers
in otheryears (Appendix1).
We found threeplovers,whichshowedno signsof nesting,at FrenchCreek
mouth. No subsequentvisitswere made that season,but in July 1979 Parker
found a chickthere. At PenasquitosLagoon in 1978 he found four adultshe
suspected
werenestingand, in 1979, a pair witha nestwherewe hadfound
no plovers in 1978.
San Diego County has historicalrecordsof breedingploversfor a number
of coastalsites(Appendix 1). Imperial Beach and Coronado beachfronts,
Ocean Beach, MissionBay beachfront,Pacific Beach, Del Mar Beach,
Buena Vista Lagoonand the Oceansidebeachfront,all formernestingsites,
have beenso alteredin recentyearsby development,erosionor humanuse,
that habitatno longerexistsfor nestingSnowyPlovers.Conversely,a major
breedingsitein the San DiegoBay areawascreatedwith the construction
of
the Western Salt Works where a number of plovers nest undisturbedon
levees.
ORANGE COUNTY once supported substantialnumbers of nesting
SnowyPlovers(Appendix1) butduringour surveyheldonly2% of thepairs
on the mainlandcoast;all were at the BolsaChica Oil Fields(Table2). These
SNOWY
PLOVER
BREEDING
STATUS
oil fields,on disusedsaltevaporators
in BolsaChicaBay, offerrelativelyundisturbed
alkaliflatsfor nesting.BayfillnearSunsetAquaticParkconstitutes
theonlyotherrecentlyusednestingareain OrangeCounty.Nestswerecollectedfrombeachesin OrangeCountyuntil1940. By 1947 Cogswell(1947)
notedthat formerlygood beachnestinghabitathad deteriorateddue to increasedhumanuse.Becauseof rakingand heavyhumanuse,beachnesting
habitatis no longersuitablefor Snowy Plovers.Beachesare now raked
regularlyfromNewportBay northto SunsetBeach.NewportBay spitand
SunsetBeach have some unraked, vegetatedportionsof upper beach, but
BolsaChicaand Huntingtonstatebeachesare completely
rakedand denuded
of vegetation.Althoughwe found no ploversat the fenced-offLeastTern
nestingsiteat the SantaAna Rivermouthon the southend of Huntington
StateBeach,we suspectone or two ploverpairscouldnestat thissmall,undisturbed oasis.
Althoughno ploverswere found during our survey, LOS ANGELES
COUNTY oncesupportedmanybreedingpairs.Recordsof nestson beaches
adjacentto metropolitanLos Angeles,at Redondoand Ballona,are all prior
to 1908 (Appendix 1), althougha plover incubatinga nest amid many
humanbatherswasphotographedon ManhattanBeachin 1947 (Cogswell
1947). In 1903 one eggcollectorreportedcounting50 pairsof ploversalong
a 2 milestretchof beachbetweenBallonaand SantaMonica(NMNH eggset
31481). In 1938 a set of eggswascollectedfrom a beachwheresixplover
nestswere said to be present among those of Least Terns 8 km north of
Malibu (WFVZ egg set 3497). We have been unable to find recordsof
nestingon beachesin LosAngelesCountysince1949, when one incubating
adultwasreportedfrom MalibuBeach(Stager1949). The frequentrakingof
all countybeachesnow precludesthe possibility
of SnowyPlovernesting.
In VENTURA COUNTY beachesand river barsfrom Mugu Lagoonto the
Santa Clara River mouth supported14% of the plover pairs on the coast.
Sixtypercentof the Ventura Countybirdswerefoundon the relativelyundisturbedspitsof Mugu Lagoonat Pt. Mugu Naval Air Stationwhichis offlimitsto the public. On Ormond Beach, adjacentto Mugu Lagoon and extendingnorthwestto Hueneme, ploverswere found on pond marginsthat
are a continuationof the Mugu Lagoon wetlands.Exceptat Mugu Lagoon
and McGrath State Beach, where we found the remainingSnowy Plovers,
beachhabitatin VenturaCountyis mostlyraked,residentially
developedor
heavilydisturbedby off-roadvehicles.While recordsfrom museumeggcollectionssuggestthatploversoncenestedalongmostof the beachfromMugu
Lagoonto the cityof Ventura, on our surveyploverswere absentfrom the
mostdisturbedsections(Appendix 1).
SANTA BARBARA COUNTY held the secondhighestnumberof coastal
breedingSnowy Plovers,with 16% of the estimatedpairs.The moststriking
changethat hasoccurredin thiscountyis the disappearance
of the species
from breedinggroundssoutheastof Point Conception(Appendix1). At El
Esterospits(Carpinteriaand Sandyland),SantaBarbaraBeachand Goleta,
where at least58 clutcheswere collectedbetween 1891 and 1948, we were
unableto find suitablywide or untrampledbeachhabitat(lessthan 100%
coveredby human footprints).In 1927 one collectorcounted24 pairsat
Goleta (WFVZ egg set 31500) where we found no plovers on the small,
7
SNOWY
PLOVER
BREEDING
STATUS
heavilyusedpublicbeach.On smailbeaches
westof Goletawefoundsome
suitablehabitatbut no plovers.Apparentlyerosionof habitathasbeena major factoreliminatingSnowyPloversfrom southeastern
SantaBarbaraCounty. We discoveredlargenumbersof ploverson the beachesand river mouths
of northern Santa Barbara County, primarily on Vandenberg Air Force
Base'sPurisimaPoint beach, which is off-limitsto the public.
SAN LUIS OBISPO COUNTY, with 9% of the coastalbreeders,hasonly
two large, potentialnestingareas,the northernsectionof the Niporeo Dunes
(extendingfrom the Santa Maria Rivernorthto PismoBeach)and Morro Bay
spit (Table2). At the Nipomo Dunesfew ploverswere found away from the
SantaMaria River.Two nestsat PismoBeachin 1965 arethe onlypreviously
reported nests on this sectionof the coast, which seemed to be suitable
breedinghabitat.Heavy human use, includingintensivevehicletraffic,probablyresultsin the paucityof nestingploversaway from the Santa Maria River
mouth. Plovers were dispersedalong the entire length of Morro Bay spit,
whichappearedto be lightlyusedby humans.Documentationfor nestingin
the Morro Bay area extends back to 1926.
MONTEREY
COUNTY
held 12%
of the coast's and over two-thirds of
MontereyBay'ssizableSnowyPloverpopulation.Ploversoccurredprimarily
from Marina Beach to MossLanding'sWesternSalt Works. While increased
human disturbancehas probablyreduced the number of ploversthat now
breed on the accessiblebeaches north of the Salinas River mouth, the loss
hasprobablybeenpartiallycompensatedfor by the developmentof relatively
undisturbednestinghabitat at the Moss Landing salt evaporators.Where
ploversonce nestedfrom PacificGrove to Marina Beach (Appendix 1), they
no longer do so since high tides now wash to the base of high wave-cut
dunes.
SANTA CRUZ COUNTY supported5% of the coastalbreedingplovers,
all in two locations(Table2). At the PajaroRiver mouthploversnestedon
the beach and on open alkali flats in a salt marsh behind the housing
developmentnorthof the river. Wilder Beach,known as a nestingarea since
1922, held an unusuallyhigh numberof ploversfor its small(0.5 km long)
size.Eggrecordsfrom Palm Beachand the mouthsof Moore, Four-Mileand
Scott creeks indicatethat in the past other small pocket beacheson north
Monterey Bay supported nestingplovers (Appendix 1). In 1979 Vollmer
(pers.comm.) found three adultsand a broodat the LagunaCreek mouth,
and Metropulos(pers.comm.) found eightadultsand at leasttwo broodsat
the mouth of Waddell Creek. Apparentlythe speciesstillbreedssporadically
on some of these publicly-usedpocket beaches.
In SAN MATEO COUNTY, which supportedjust over 1% of the coastal
birds, breedingSnowy Ploverswere found on the little disturbedbeach at
Afio Nuevo State Reserve and on the beach and sand flats at Pescadero
Creek mouth. Nesting records from Afio Nuevo are very recent but
Pescaderohas been a known nestingarea since 1927 (Appendix 1). The
beachat FranklinPoint,just north of Afio Nuevo, whereeggswerecollected
early in the century,haserodedto a narrowterracebackedby dunesperched
on a 1-3 m high bank. At the time of our surveyit was an unsuitablenesting
site.
SNOWY
PLOVER
BREEDING
STATUS
It is understandablethat the heavilyeroded and intensivelyused beaches
of SAN FRANCISCO COUNTY currently provide no habitat for nesting
Snowy Plovers, but it is interestingthat no historicalrecords of breeding
could be found. Probablythey nestedon the dune-backedOcean Beach
before urban development spread to the shoreline.
The ploversfound in MARIN COUNTY represented4% of the coastal
population.All but one pair werefound on the beachesof the PointReyes
National Seashore;the remainingpair was on the Bolinas Lagoon spit.
Althoughthere appearedto be suitablehabitatat Dillon Beach, at the mouth
of Tomales Bay, no ploverswere found. Historicalrecordsin Marin County
are limited to a singlenest found on Point Reyes Beach in 1926 (Booth
1926) and a few unpublishedobservationsof nestsor broodsat Limantour
Esteroand BolinasLagoon by PRBO personnelin the 1970s.
Beachesnear Bodega Bay in SONOMA COUNTY are only occasionally
used by small numbersof nestingplovers.Although we found no plovers
during the 1977 survey, a nest was found in late April on Salmon Creek
Beach in 1978 (Appendix 1). The nest and incubatingadult disappeared
within two days. Snowy Plovers probably bred regularly on the spit of
BodegaHarbor but, sincethe area hasbeen developedand becomeheavily
usedfor recreation,breedingis now probablyirregularat best.
MENDOCINO COUNTY'S share of the coastal population, 2%, was
locatedon 7.4 km dune-backedMacKerricherBeach.We found no previous
countybreedingrecords,but suspecta lack of observersis responsible
for the
absenceof previousrecords.
HUMBOLDT COUNTY, with 6% of the coastalplovers,held more birds
than any countynorthof MontereyBay. Thisundoubtedlywasrelatedto the
extensiveamount of potential habitat, consistingof 115 km of sand beach
backedby dunesor wetlands(Anon. 1971). Recordsof nestingin the HumboldtBay area extendbackto 1899 (Appendix1) but are lackingfor beaches
to the north where we found breedingbirds (Table 2). Absenceof past
recordsfor the northern area probablyis related to a lack of observers.We
cannot explain the absenceof nestingSnowy Ploverssouth of Humboldt
Bay, at the north and south spitsof the Eel River and at McNutt Beach.
DEL NORTE COUNTY held just over 1% of the coastalpopulationwith
nestingbirdson the beachat Lake Talawa and the Smith Riverspit.Yocom
and Harris (1975) suspectedbreeding in the Lake Talawa area but no
definiterecordswerereporteduntilWidrig (pers.comm.)foundthem nesting
there in May 1977. Lack of observercoverageis undoubtedlyresponsible
for
the paucityof historicalrecordsfor thiscounty.
Coastal Habitat
Coastalhabitatsweregroupedintosixtypes:1) bluff-backed
beach:beach
backedby cliffs,bluffsor other non-dune, non-wetlandhabitat;2) dunebackedbeach:maybe interruptedbya river,creek,pond, lagoonor saltflat;
3) smallpocketbeach:shortbeachat the mouthof a river, creekor lagoon
anddelimited
anddominated
bybluffsor rockypoints;4) spit:a sandspitor
bar separatingthe ocean from a coastalwetland;5) estuarinemargin:
disturbed
or naturallyopenareain or at the marginof an estuaryor a lagoon
(often a saltflat); 6) salt evaporator.
SNOWY
PLOVER
BREEDING
STATUS
Table2. Numbers
ofSnowyPlovers
breeding
incoastal
California.
SanDiegoCounty
to SanMateoCountyfrom1978survey;MarinCountyto DelNorteCountyfrom
1977survey.
Areatypesareexplained
in thecoastal
habitat
section
of text.
Area
Est.
Type
Pairs Adults Males Females niles Broods Nests
131
257
19
37
16
8
1
1
1
San DiegoCounty
Total
Known
Known
Juve-
TijuanaR Mouth
4
Silver Strand Beach
4
3
5
1
2
SilverStrandBayShore
4
3
6
1
2
WesternSalt Works
6
16
31
12
12
Sweetwater R Mouth
5
9
18
3
6
SanElijoLagoon
5
12
23
6
4
BatiquitosLagoon
5
3
6
3
AguaHedionda
Lagoon 5
StaMargarita
R Mouth 4
27
37
54
74
23
16
French,AlisoCr Mouths
OrangeCounty
BolsaChica Oil Fields
3
19
19
2
1
5
2
10
10
8
8
71
136
MuguLagoonSpits
4
41
82
36
27
2
6
Ormond Beach
2
14
25
14
6
1
1
McGrath State Beach
Santa Clara R Mouth
2
2
3
13
4
25
2
12
1
5
1
1
2
1
Santa Barbara County
Santa Ynez R Mouth
Purisima Point Beach
2
2
82
5
55
158
10
109
1
30
1
38
2
6
So. NiporeoDunes
2
4
4
Santa Maria R Mouth
2
18
35
10
13
2
1
43
86
3
40
6
80
2
24
3
27
13
4
8
2
9
3
VenturaCounty
San LuisObispoCounty
No. NiporeoDunes
MorroBaySpit
2
4
MontereyCounty
60
115
2
12
3
23
SalinasR Spit
4
16
31
SalinasR State Beach
Western Salt Works
2
6
4
24
7
47
3
7
MossLndng.-Zmudowski2
2
4
25
50
4
17
34
Wilder Cr Beach
3
8
16
San Mateo County
3
2
1
2
1
2
4
2
2
PajaroR Spit
1
6
Point Sur Beach
Marina Beach
SantaCruz County
1
2
2
6
2
1
5
2
1
2
1
4
7
2
2
8
1
2
2
5
6
8
5
3
7
13
Afio Nuevo Beach
2
5
9
4
4
1
Pescadero
Cr Spit
4
2
4
2
2
1
10
SNOWY
PLOVER
BREEDING
STATUS
Table 2 (Cont.)
Area
Est.
Type
Pairs
Marin County
BolinasLagoon Spit
Limantour EsteroSpit
DrakesBeach Spit
Point Reyes Beach
Mendocino County
4
4
4
2
21
1
4
1
15
9
MacKerricher Beach
Total
Known
Adults Males
40
1
8
2
29
15
Known
Females
Jureniles
Broods
Nests
1
3
3
1
1
12
9
7
8
2
9
15
Humboldt County
So. HumboldtBay Spit
No. HumboldtBay Spit
Elk R Spit
Lanphere Dunes Beach
Mad R Spit
4
4
4
2
4
32
4
6
I
2
10
54
7
11
1
3
17
Clam Beach
2
1
2
1
1
Big Lagoon Bar
Del Norte County
4
8
7
13
11
4
8
3
2
5
5
1
2
9
7
1
1
Lake Talawa Beach
2
3
5
2
2
1
Smith R Spit
4
4
6
2
4
2
498
954
TOTALS
287
275
25
57
72
Smallpocketbeaches
aresometimes
similarto spitsbutaredistinguished
byseveral
characteristics.
Because
pocketbeaches
areshortandusually
span
less
than1.5kmofcoastline,
theyarealmost
always
dominated
byalelimiting
cliffsor bluffs.Significant
vegetated
duneor hummock
development
behind
thebeachis usuallylacking.Spitsmaybe delimited
at eitherendby cliffs,
bluffs,dunesor lowlands
but, because
of theirlengthand the presence
of
fairlyextensive
lowwetlands
behindthem,theyarenotdominated
bytoweringtopographic
features.Theyusuallyhavewelldeveloped
duneor hummock structures between the beach and the wetland.
The six habitats
differedin importance
to nestingSnowyPlovers.The
habitat
typeforeachareasupporting
plovers
onthesurveyisdesignated
in
Table 2.
Noneof the manybluff-backed
beaches
surveyed
heldnesting
Snowy
Plovers;
mostwerelowandnarrow,offering
littlehabitat
freefromperiodic
tidalinundation.
Oneexception,
theprivately
ownedisolated
5.8 kmMcNutt
Beachin HumboldtCounty,wasbackedby a stretchof upperbeachover
100 m wideabovethe hightidelinebut, likeotherbluff-backed
beaches,
heldnoplovers.
No obvious
reason
fortheirabsence
therewasapparent.
Dune-backed
beaches
supported
34% ofthepairsonthecoast;
allexcept
PointSur, DillonBeachandLanphere
Beachwereinterrupted
at leastonce
by rivermouths,creekmouths,pondsor lagoons.
Althoughthesewetlands
11
SNOWY
PLOVER
BREEDING
STATUS
spannedonly 7% of the 112 km of dune-backedbeachesthat supported
plovers,46% of the 170 pairson thesebeacheswere near thesewetlands.
Densitiesof ploversalong dune-backedbeacheswere not particularlyhigh
comparedto thosealong spitsexceptat PurisimaPoint and Afio Nuevo State
Reserve (Table :3).
Small pocketbeachesproved to be generallypoor nestinglocations,collectivelyholdingonly 2% of the estimatedpairs;we foundploverson only 2
of 25 with potentialnestinghabitat.At one of these,FrenchCreek mouthon
Camp Pendleton,we found three adultsthat showedno signsof nesting.
The othersite,Wilder Beach, Santa Cruz County, wasunusualamongsmall
pocketbeaches,havinga smallbut welldevelopedterraceof vegetatedsand
hummockson its upper beach. Frenchand Wilder creek mouthssharetwo
importantcharacteristics:
both are off-limitsto the publicand both are near
other major nesting areas; French Creek is :3.4 km north of the Santa
MargaritaRiver mouth and Wilder Creek is on the north side of Monterey
Bay. Other Santa Cruz County pocket beachesoccasionallyhold plovers
suchas in 1979 when nestingbirdswere found at Lagunaand Waddellcreek
mouths.Usually,however,smallpocketbeachesprovidethe only beaches
alonglong stretchesof bluff-backedcoast,are consequentlyheavilytrampled
by bathers,and thereforeare difficultplacesfor ploversto nestsafely.
Some of the highestdensitiesof ploverswere on spits(Table:3).Sand spit
habitat, which held 43% of the pairs along the coast, was undoubtedly
enhancedby the fairly extensiveborderingwetlands.Tidal flatsand other
open areas in marshesafforded alternate, often productivefeeding areas,
and a refugefrom humandisturbance
on the beaches.At the TijuanaRiver,
Santa MargaritaRiver, Mugu Lagoon and Pajaro River spits,saltpans in adjacentmarsheswere also usedfor nesting.Snowy Ploversoften were seen
moving between salt pans, tidal flats, and beaches,indicatingthese areas
function together in providing habitat. Supplemental feeding and nesting
areasprovidedby wetlandsand saltflatscausedplover densities(measured
along the lengthof the spits)to be higherthan they might otherwisehave
been. For example,spitsat the TijuanaRiverand nearbySilverStrandbeach
in San Diego County both receiveheavy human use. However, the spit at
the Tijuana River adjoins a salt marsh with extensivesalt flats which the
ploversuse, while Silver Strandbeachis separatedfrom the few remaining
undevelopedportionsof the bay shoreby a major roadway.The densityof
ploversalongthe Silver Strandspitwas lessthan a tenth that alongthe Tijuana River spitsand wasnoticablylowerthan that on otherspits(Table:3).
Spitsthat supportednestingploversvaried in topography,vegetationand
compositionof the adjacentwetlands.South of Point Conception,Santa
BarbaraCounty, most spitswere coveredby low, vegetatedmounds, but to
the north they were oftencoveredby extensivevegetateddunes,sometimes
over :30 m high.
Open areasaroundestuaries,whichheld 12% of the coastalpairs,include
lagoonmargins,disturbedareas(saltpans)in saltmarshes,and bayfill. All of
theseareaswere usuallylevel, with topographicreliefexceeding50 cm only
at San DiegoBay fill sites,whichwere 2 to :3m abovethe bay margin,and at
Bolsa Chica Oil Fields, where roadwayswere built 2 m above the marsh.
Substratewas alwaysat leastlightlycompactedand debrisusuallycovered
12
SNOWY PLOVER BREEDING STATUS
lessthan1% ofthearea.Marshsaltpanalsooccurred
behindthespitsat the
TijuanaandPajarorivermouths,at MuguLagoonandat theMossLanding
Salt Worksbut, becausesaltpansfunctionedas part of a broaderhabitat
systemat theseareas,they are considered
as subareas
of the spitsor salt
worksrather than separatelyas open areasin estuaries.
Saltevaporators,
whichsupported
8% of the pairson thecoast,afforded
Snowy Ploversa man-madehabitatat estuaries.Ploversnestedon low dikes
separating
evaporator
pondsandonfloorsof driedevaporators.
Theyfedon
theabundant
brineflies(Ephydridae)
atpondmargins.
Dikesvariedin height
fromlessthan1 m to 2 m abovethewatersurface.
We foundmostplovers
on unvegetatedportionsof the lower dikes, except where WesternGulls
(Larusoccidentalis),CaspianTerns ($terna caspia),Forster'sTerns ($.
forsterOor BlackSkimmers(Rynchops
niger)werenesting.
In generalthe densityof nestingploversdecreasedfrom southto north
(Table4), indicating
thatwhenhumandisturbance
wasnot overwhelming,
southernratherthan northernbeachesprovidedthe besthabitat.
Table3. Densities
of SnowyPloverpairsestimated
fromcensus
totalsin Mayand
June1978 in fourof sixhabitattypessurveyed
in southern
and centralCalifornia.
Kilometers Hectares Pairsper
of Coastline'of OpenArea Km or Ha
Small Pocket Beaches
FrenchCr Mouth
WilderCr Beach
Dune-backed
0.5
0.5
4.0
16.0
12.5
2.3
9.2
20.9
0.9
5.6
10.1
1.1
1.9
2.2
6.0
1.2
2.2
2.1
0.6
4.6
Beaches
Ormondto VenturaBeach
Santa Ynez R Beach
PurisimaPoint Beach
Nipomo DunesBeach
Point Sur Beach
Marina Beach
SalinasR to PajaroR
Afio Nuevo State Reserve
Spits
TijuanaR Mouth
SilverStrand
3.7
(15)
13.4
SantaMargaritaR Mouth
MuguLagoonSpits
Morro Bay Spit
SalinasR Spit
PajaroR Spit
1.9
8.6
8.0
2.0
2.6
PescaderoCr Spit
EstuarineMargins
SweetwaterR Mouth
San ElijoLagoon
BatiquitosLagoon
Agua HediondaLagoon
BolsaChica Oil Fields
1.0
5.1
0.4
(52)
(12)
(3)
17.5
63
1.5
20
68
19.5
4.8
5.0
8.0
6.5
2.0
0.5
0.2
2.0
1.4
0.1
'Does not includeriprapped,urbandevelopedor bluff-backed
shoreline.
13
SNOWY
PLOVER
BREEDING
STATUS
Table4. Densitiesof SnowyPloversalongsandbeachesin coastalCaliforniacounties.
Lengthsof sandbeachin each countyfrom Anon. (1971).
Estimated
Pairs on
Estimated
Estimated
Beaches&
Pairsper
Pairsin
Pairsper
of Sand
Beach
Associated
Flats't'
Kilometer
of Beach't
Coastal
Habitatõ
Kilometer
of Beachõ
San Diego
Orange
LosAngeles
36.7
41.4
70.8
73
0
0
2.0
0.0
0.0
131
10
0
3.6
0.2
0.0
Ventura
Santa Barbara
29.0
27.7
71
82
2.4
3.0
71
82
2.4
3.0
SanLuisObispo
Monterey
41.7
33.5
43
36
1.0
1.1
43
60
1.0
1.8
19.6
12.4
4.0
35.1
17.4
12.4
115.4
19.8
25
7
0
21
1
9
32
7
1.3
0.6
0.0
0.6
0.1
0.7
0.3
0.4
25
7
0
21
1
9
32
7
1.3
0.6
0.0
0.6
0.1
0.7
0.3
0.4
Kilometers
County
Santa Cruz
San Mateo
San Francisco
Marin
Sonoma
Mendocino
Humboldt
Del Norte
Estimated
Omitsbirdsat saltworks,oil fieldsand northernSan DiegoCountycoastallagoons.
Includesall estimatedpairsfrom alongthe coast.
Generallynestswerelocatedin flat openareasdevoidof, or sparsely
coveredwith,vegetationor driftwood.On beachesin particular,nestswere
oftenplacednextto someobjectsuchasa pieceofdriftwood,
kelporplastic.
Siteswereusuallywithin100 m of waterbutoccasionally
wereseveralhundredmetersawaywhentherewasnota formidable
barrierof vegetation
between the nestand the water. The absenceof sucha barrieris probablyim-
portantso thatnewly-hatched
chicksmayhaveeasyaccess
to the shore.
Broods
generally
werelocated
feeding
nearwater,butwhendisturbed
would
retreatto the upperbeachwherethe chickswouldcrouchby driftwoodor
run into vegetationto avoid beingseen.
Disturbance to Coastal Habitat
Severalfactorsaffectthe qualityof breedinghabitat.Humanshavea con-
siderable
impact
through
theirrecreational
activities
andbyphysically
altering
areaswithresidential,industrial
and recreational
development.Otheragents
of disturbance
identifiedin otherstudies(Pageunpubl.data)are highwinds,
highwater levelsand nestpredators.
14
SNOWY
PLOVER
BREEDING
STATUS
The intensityand type of human activityvaried considerablyamongsites.
Someactivitiesprecludedthe useof beachesfor nesting.In all of Los Angeles
County and partsof Orange County, entirebeachesare groomedwith large
rakeswith tines 5 to 8 cm apart. These rakesare draggedbehind motorized
vehiclesfrom the waterlineto pavementor the low retainingwall bordering
the beaches.Since this is done once a week or more often, no nestcould survive even if human use were not as intensive as it is. Other activities, such as
the drivingof publicoff-road and militaryall-terrainvehicles,while causing
considerabledisturbanceand sometimesnestdestruction,do not alwaysprevent ploversfrom nesting.
To measurethe effectof human activityon the densityof nestingplovers
we had hoped to find physicallysimilarsegmentsof coastlinethat received
different intensitiesof human use. We found only one place where
reasonablysimilarareascouldbe compared.In Santa Barbaraand San Luis
Obispo countiesthere are two fairly long neighboringstretchesof dunebacked beach, the dunes north of Purisima Point on Vandenberg Air Force
Baseand the vastNipomo Dunes System(SantaMaria River dunes)farther
north. They differ primarilyin the extent of associatedwetlands;Purisima
Point dunesare interruptedby one creek mouth and the Nipomo Dunesby a
river and two creeks. However, the human use that these beachesreceive is
quite dissimilar,with the Purisima area receiving almost none and the
Nipomoarea receivinga lot, includingextensiveoff-roadvehicletraffic.The
densityof nestingploversalong Nipomo Dunes beachis lessthan a fifth of
that along PurisimaPoint beach, despitethe fact that the Nipomo systemhas
more wetlandhabitat.In addition,nestingploversare dispersedalongmuch
of the Purisimacoast,whereas78% of the ploverson Nipomo Dunesbeach
were concentratedaround the mouth of the Santa Maria River. Although a
more thoroughpopulationand habitatstudywould be necessaryto assess
the causesof thesedisparatedensities,they do suggestthat human activities
can severelydepressthe number of nestingplovers.
The introduction of Marram Grass (Ammophila arenaria) to stabilize
coastalduneshas alteredthe physicalstructureof beachesand has almost
certainlydetrimentallyaffectednestingSnowy Plovers.We found Marram
Grassfrom Ventura County north; it was well establishedin many areas
north of Point Conception.The formationof the foreduneparallelto the
shorelinetypicallybuiltby the sand-binding
rootsof MarramGrassdecreases
open, unvegetatedareasabovethe tidelinesand thereforethe amountof
potentialnestinghabitat.Vegetateddunesof beachesdominatedby the
nativedunegrass(Elymusmollis)are usuallyperpendicular
to the shoreline
and are oftenseparatedby expansesof fairlyflat sandthatextendbackfrom
the upperbeachand are favoredplovernestingsites.Barbouret al. (1976)
foundthatAmmophila-dominated
beachheldabouthalfthe numberof plant
species,had lessopen area and had steeperslopesthan adjacentbeach
dominatedby Elymus. Slobodchikoffand Doyen (1977) found that Ammophilamarkedlydepressed
the abundanceand diversityof sanddunearthropodsin California.SinceSnowyPloversoftenfeedon insects
wellabove
the high tide line, their food supplymay be detrimentallyaffectedby the
presenceof Ammophila.The PipingPlover (Charadriusmelodus),a bird
15
SNOWY
PLOVER
BREEDING
STATUS
with similar habits, declined in numbers on a New York State beach after
Ammophilawas planted in its nestingarea (Wilcox 1959).
Among non-humanrelatedfactors,predators,whichon the coastappear
to be mainlycorvids,are knownto have a markedeffecton plovernesting
success(Pageunpubl. data and Wilsonpers. comm.). Ravenswere seenat
only 6 and crowsat 4 of 107 sitessurveyedsouthof the Golden Gate. This
spottycorvid distributioncontrastswith the north coast, where ravenswere
seenon 34 and crowsat 10 of the 41 sitessurveyed.We believethat nesting
ploverssouthof the GoldenGate may sufferlessfrom corvidnestpredation
than those to the north.
Strongwindsand high water are the other factorsaffectingbreedingsuccess.At Pajaro Dunes, Santa Cruz County, strongwindswere found to be a
major causeof nest loss (Warrinerand Warriner unpubl. data). Extremely
high tides, especiallyspringtides in June and July, washedaway nestsat
Limantourspit, Marin County (Pageunpubl. data). Eggcollectorsnoted that
hightideswashedaway a nestin San DiegoCounty (WFVZ eggset91,240)
and nearlyinundatedone in Santa BarbaraCounty (CMNH egg set 1192).
Althoughit is impossibleto reach any valid conclusionabout the effectof
high winds on Snowy Ploversduring this survey, we can comment on the
probableeffectsof high water. The winterof 1977-78 was unusuallystormy
and high wavesseverelyeroded beachesin southernand centralCalifornia.
By early May, when we startedthe surveyof the southcoast,many eroded
beacheshad not yet recoveredtheir normal sand loads. One employeeat
SilverStrandState Beach, San Diego County, told us that 45 m of the normal 100 to 130 m of beachwidth had beenremovedby stormsthe previous
winter. We also found that several coastal lagoons, whose level sandy
marginspreviouslyprovidednestinghabitat,were floodedby winterrainsup
to the vegetatededgesor steepbanksand thereforelackedsuitablebreeding
habitatat that time. Later in the seasonwater levelsdroppedin mostlagoons,
whichthen were usedby nestingplovers.Becausemuch of the floodedand
eroded coastalhabitateventuallywasrestored,nestingareasappearedor increasedin sizein some locationsafter our survey. These habitatalterations
undoubtedlywere responsiblefor some shiftingof nestingbirds between
locationsduringthe summer.
III.
SAN FRANCISCO
R. PHILIP
HENDERSON
BAY AND THE INTERIOR
and GARY
W. PAGE
,SanFranciscoBay
Havinghabitataffinitieswiththe interiorand beingsomewhatisolatedfrom
the open coast,San FranciscoBay fallsinto an intermediatecategorybetweenthe coastand the interiorand thereforeis consideredseparately.During the survey351 adultploverswerefoundin the bay with 90.6% of these
in ALAMEDA COUNTY, 5.4% in SAN MATEO COUNTY• and 4.0% in
SANTA CLARA COUNTY (Table 5); they occurredat functioningand
abandonedsalt evaporatorssouth of the San Mateo Bridge. The majority
were on the east side of the bay, on leveessurroundingevaporatorsbrimming with water and on leveesand flats in partly dry evaporators.Their
16
SNOWY
PLOVER
BREEDING
STATUS
distributionon levees was patchy and their absencefrom some was inexplicable, although when found, birds were almost always on levees
separatingone evaporatorfrom another and seldomon leveesseparating
evaporatorsfrom the bay or the land. Nestswere locatedon leveesaround
filled or partly dry evaporatorsor on dry flats in partly empty or disused
evaporators.
Snowy Ploversbred at saltevaporatorsin South San FranciscoBay as early as 1918; Grinnell et al. (1918) noted that "a great many pairsnestedon
dikesseparatingsalt ponds on the eastside of the bay, at the Alvaratio salt
works, and that workmen had reported having broken many eggs with
wheelbarrows,"As one nest was collected 15 May 1919 on a levee near
RedwoodCity, they alsonestedon the westsideof the bay earlyin thiscentury. Subsequentscatteredbreedingrecordsat the Haywardsaltponds,near
the DumbartonBridge, near Alvisoand near Belmont are summarizedin Appendix 1; we found birdsin all theseareas.We found none on sandfill at the
end of the main runway at Oakland InternationalAirport where Manoils
(pers. comm.) found a few adultsin 1977, and Feeney (pers. comm.) saw
five adults in 1979, nor did we have any reportsof breedingon the south
shoreof Alameda where there have been occasionalrecentrecords(Appendix 1).
In summer, 1971, during an extensive survey of the breeding birds of
South San FranciscoBay, Gill (1972) found 15 Snowy Plover nestsat two
locations,on the Knapp Gun Club property4 km northwestof Alviso, and
on levees at the east end of the Dumbarton Bridge. He concluded that
"breedingpopulationsof SnowyPloverswithinthe studyareawouldapproximate . . . 150 pairs. This would include nestingactuallyobservedduring
1971 plusobservationof otheradultbirdswithinthe majornestingareasand
sightings
of additionalbirdsin areaswith suitablenestinghabitatsuchas Bair
Island,Moffett Field, and the Drawbridge-CoyoteCreek areas."
We found ploversbreedingin both areaswhere Gill found them breeding
but at one, the Knapp Gun Club property,they were much lessnumerous
duringour survey.At Bair Island,the MoffettField area and the DrawbridgeCoyote Creek area where Gill found birds but no nests, we found neither
nestsnor birds.At mostonly 199 of the ploverswe countedwere withinthe
area Gill estimatedheld 150 pairsin 1971. Becauseof the patchinessof the
plovers' distribution in South San Francisco Bay, Gill may have
overestimated numbers, so that the two setsof data should not be construed
as indicatinga decline. At bestthe data indicatethat sinceat least 1971 the
man-made salt evaporatorsof South San FranciscoBay have been one of
the most important breeding areas in the state.
AlthoughGill (pers.comm.) foundthreepairsnestingon a saltevaporator
levee in July 1975 at Little Island, NAPA COUNTY, our searchof this and
many other leveesin North San FranciscoBay failed to turn up a single
Snowy Plover in 1978. The levee at Little Island was covered with 600
nesting Caspian Terns, several hundred roosting California Gulls (Larus
californicus)and 80 roostingWhite Pelicans(Pelecanuserythrorhynchos).
Sincethis crowdedlevee seemedto be the only suitablenestingarea, we
believethat the breedingof smallnumbersof ploversat saltevaporatorsin
North San FranciscoBay is probablyirregular.
17
SNOWY
PLOVER
BREEDING
STATUS
Table 5. Number of Snowy Ploversin San FranciscoBay during June 1978 survey.
Total
Adults
Known
Males
Known
Females
Juveniles
Broods
Nests
San Mateo County
Santa Clara County
Alameda County
19
14
318
10
7
85
2
4
83
2
3
3
3
2
50
1
35
TOTALS
351
102
89
8
55
36
Table 6. Numbersof Snowy Ploversfound in 1978 in the Californiainterior.
Asterisks(') indicatefirstreportedbreedingrecords.
Imperial County
Salton Sea
Riverside County
Salton Sea
Total
Known
Known
Adults
Males
Females
216
78
82
4
1
77
61
14
8
' Seaties Lake
16
4
4
Kern County
34
6
4
2
' Koehn Lake
26
10
8
Goose Lake
2
Kings County
1
1
' Tecopa Marsh
Owens Lake
7
4
3
499
115
81
Deep SpringsLake
Mona County
1
2
1
1
13
384
6
5
181
139
33
Mono Lake
384
208
' Honey Lake
Modoc County
208
391
81
' Lower Alkali Lake
92
22
' Middle Alkali Lake
36
13
' Upper Alkali Lake
230
33
1843
TOTALS
18
2
1
1
9
2
1
1
4
35
21
1
Lassen County
Goose Lake
10
1
522
' Tinemaha Reservoir
7
1
Inyo County
Salt Lake
Nests
10
10
Corcoran Reservoir
Broods
216
San Bernardino County
Harper Lake
Rosamond Lake
Juveniles
1
3
31
28
20
4
11
8
11
10
3
13
5
45
38
51
42
18
8
4
11
597
433
110
147
11
90
SNOWY
PLOVER
BREEDING
STATUS
The Interior
Duringthe 1978 surveywe found1843 adultSnowyPloversat 18 interior
locations;nestsor chickswere found at all except4 (Table6). At 2 of those4
locations,RosamondLake and GooseLake in Kern County, the presenceof
suitablenestinghabitatsuggestedprobablebreeding.
The male to female ratio was unbalancedat 10 males to 8 females, probablybecausefemalesincubatefor mostof the daylighthoursand were more
difficultto find on their scatteredneststhan males, which concentratedat
feedingplacesby water.Unfavorablelightingconditionsor largenumbersof
birdsoftenpreventedus from determiningthe sexof somebirds.Becauseof
these factors, we have used the total number of adults rather than the
estimatednumber of pairs as a measureof populationsizein the interior.
The Salton Sea in IMPERIAL
and RIVERSIDE
COUNTIES
accounted for
12.3% of the adultsfound in the interior.This percentagemighthave been
slightlyhigherhad we not accidentally
omittedthe LupineWash areain ImperialCounty. Of the 226 adultsfound, 96% werein IMPERIAL COUNTY
and 4% were in RIVERSIDE COUNTY. Althoughthey occurredaroundthe
entire Salton Sea perimeter, the major concentrationswere on the west side
from Desert Shores to the north half of the Salton Sea Naval Test Base and at
the mouthof San FelipeCreek, and on the eastsidefrom BombayCreekto
the Wister Unit of Imperial Wildlife Area and on beachessouth of the Wister
Unit. They occurredalongopen, gentlyslopingshorelinesand in the region
of washes. A few were found on fiats inside diked reservoirs but none on diked
or denselyvegetatedshoreline.Althoughmostploverswerelocatedin areas
with little human disturbance,some were found between Desert Shores and
SaltonCity, at DesertBeachand at BombayBeach,threeareasheavilyused
by people.
The Salton Sea formed from 1905 to 1907 when structural flaws in a canal
systemallowed water from the Colorado River to flow uncheckedinto the
Whitewater River Basin. Since then agriculturalrunoff has maintainedand
even causeda risein waterlevels.We found no informationsuggesting
that
Snowy Ploversbred in the WhitewaterRiver Basin prior to 1905; a nest
taken in 1929 is the earliestknown breedingrecord.This and other reports
(Appendix1) indicatethat Snowy Plovershave been breedingat the Salton
Seafor at least50 years.Our surveyresultsindicatethatit iscurrentlyone of
the mostimportantbreedingsitesin the state (Table 6).
The only otherknownbreedinglocationin RIVERSIDECOUNTY is Lake
Elsinore.Recordsdate from a nestfound in 1939 to the sightingof three
"juveniles"(possibly
chicks?)in April 1974 (Appendix1). At the time of our
1978 surveyhighlakelevelsfloodedintosurrounding
vegetation,leavingno
suitablehabitatfor nestingploversand none were found.
SAN BERNARDINO COUNTY held 4.2% of the interiorploverpopulation at two sites,Harper and Searleslakes. Harper Lake, an alkalisink with
somemarshand open standingwater,accountedfor 79.2% of the ploversin
the county.They werefoundon the southwestmarginof the lakebedin three
separateareaswith 37 birdsat the central, 15 at the southeast,and 9 at the
northwesternmost
site. Sincewateris pumpedto at leasttwo of theseareas
afterit hasbeenusedfor irrigationin nearbyalfalfafields,the birds'habitatis
19
SNOWY
PLOVER
BREEDING
STATUS
largelyunderhumancontrol.SnowyPloverswerefirstknownto be breeding
at Harper Lake in 1977 when Hendersonfound at least67 adults,3 broods
and one nest. The lack of earlierrecordsis probablydue to the absenceof
observers.
The first reported breedingrecord at SearlesLake occurredduring our
1978 surveywith the discoveryof 16 adultsand 9 broods.Sinceall birds
werefeedingaroundstandingwaterleakingfrom a pipe at the westfacilityof
the Kerr-McGeeChemicalCorporationplant,ploverbreedingat thisheavily
industrializedlocationmay have been unusual. The only other standing
water on the alkali lakebed was a concentrated brine solution in solar
evaporationponds and an effluent smellingof sulfur from the chemical
plants.
Three locations,RosamondLake, Koehn Lake and Goose Lake in KERN
COUNTY, collectively
held1.8% of theinteriorpopulation.AlthoughRosamondLakeis usuallydry, 25% of the lakebedwasfloodedby fresh-tasting,
silt-ladenwater when surveyed.On the unvegetatedeastshorelinethe six
ploversseenwere believedto be breedingalthoughno nestsor broodswere
found. Two smallbodiesof water lay on the otherwisedry alkali flatsat
Koehn Lake. By the larger,25 ha body on the westedge of the lakebed,25
adults,2 broodsand 1 nestwerefound.One additionaladultwasseenby a 5
ha body of water near the old Saltdalesaltworks.At Koehn Lake strong
windshamperedsurveyingsothat our populationestimateisprobablylow.
We foundno previoussummerrecordsfor eitherKoehnor Rosamondlakes.
Agricultural
practiceshavechangedthe landscapeof the Sacramentoand
San Joaquinvalleysconsiderably
duringpastdecades.Most alkalinelakes
whichprovidedgoodnestinghabitathavedisappeared.The onlysuchareas
we found were in the San Joaquin Valley on the Kern l•lationalWildlife
Refugeand at GooseLake in KERN COUNTY. The onlyploversfoundwere
two birdsbelievedto be nestingat Goose Lake and a probablemigrantat
CorcoranReservoir,and an area lackingsuitablebreedinghabitat,in KINGS
COUNTY.
Historicallythe SacramentoValley probablywas not a major nestingarea
and we thereforeomittedit from the survey.The only three documented
breedingrecordswere an adultwith youngat both the WoodlandSewage
Pondsand the DavisSewagePondsin YOLO COUNTY, and a nestthatwas
collectedin 1913 near Reigo in BUTTE COUNTY (Appendix 1).
Historicallythe San JoaquinValley was probablymore importantas a
breeding area than the SacramentoValley. There are several breeding
recordsfrom near Los Banos in MERCED COUNTY (Appendix 1); one that
wasparticularly
well documented(Unglish1938), notesthat5 milesnorthof
LosBanosa 5 acrepond witha few smallislandsheld 11 SnowyPloversand
at least4 nestsin 1937. It wasthe firsttime Unglish"in fifteenyearsof field
workin the LosBanosarea"andonlythe secondtimehiscompanionTyler,
"in forty yearsin this section,"had ever recordedSnowy Plovers.Dawson
(1923) mentionsthat ploverswere breedingnear Los Banos as early as
1912. Other recordsfor the San JoaquinValley includea pair that was
"probablypreparingto nest"just eastof Firebaughin MADERA COUNTY
(Tyler 1916) and recordsfrom BuenaVistaLake in KERN COUNTY. Judgingfrom the accountsof Linton (1908) and Lamband Howell (1913) signill2O
SNOWY
PLOVER
BREEDING
STATUS
cant numbersmay have once bred at Buena Vista Lake. Both accounts
reportploversin June, and Linton reporteda two egg clutchon 2 June
1907. Linton'sdescriptionof the lake indicatedidealbreedinghabitat.Today
SnowyPloversrarely breedin the San JoaquinValley.
INYO COUNTY held the largestnumberof ploverswith 28.3% of the interiorpopulation.At Tecopa Marsh, wherethe meanderingAmargosaRiver
createdsomemarshand open standingwateron an old lakebed,Henderson
found seven adults and one brood of chicksfor the first definite breeding
record. However, the specieswas reported in small numbersduring past
breedingseasonsby Tarble (pers.comm.); the highestnumbershesawwas
12 birdson 18 June 1975. Undoubtedlysome were breeding.
Owens Lake, with 499 birds, held more Snowy Ploversthan any other
locationin the state.While we were there, waterfrom Cartago,Ash, Cottonwood and Carroll creeksbypassedthe Los AngelesAqueduct and flowed
onto the alkalinelakebedwhere it formed a shallowbody of water on the
west side. Water also seeped onto the lakebed at several locationsat its
north, southand eastsides.Most birdswere found around water, especially
alongcreeks,at creekmouthsand at seeps.Pondsadjacentto the southend
of the lake also held some plovers.Areas we were able to reach along the
marginsof the mainbodyof the lakeheldno birdsexceptnearcreekmouths.
Most nests were found on the west side but broods were found almost
everywherewhere adultswere near water. At OwensLake in 1891 Fisher
(1893) found the Snowy Plover "near Keeler, May 30 to June 4, where it
was common in small flocks of five to ten on the alkaline flats which border
the lake." He believed"the specieswasevidentlybreedingat the time, but
no eggsor young were found." The only publishedinformationwe found
verifyingnestingat OwensLake was Heindel'sobservation
in July 1975 of
130 adult-sizedploversaccompaniedby downyyoungat Dirty Socks(McCaskie 1975) at the south end of the lake.
Although Hendersonfound one Snowy Plover at Salt Lake in Saline
Valley in May 1978 and two in June 1977, he found no evidenceof
breeding.Since the birds may have been transientsor summeringnonbreedersand sincethere are no pastbreedingrecords,the ploversbreeding
status at Salt Lake remains uncertain.
A pair of nestingploversfound by Hendersonin June 1978 at the Los
AngelesDepartmentof Water and Power'sfreshwaterTinemahaReservoir
represents
the firstbreedingrecordfor thislocation.An employeeof LADWP
indicatedthe flat on whichthe plovernestedwould soonbe floodedby rising
waterso the nestmay have beendestroyed;normallythe area may not be a
nesting site.
The final INYO COUNTY sitewith SnowyPloverswasthe alkalineDeep
SpringsLake, where13 adultsand 3 broodswerefound,mostlyneara small
seep on the northwestmargin of the lakebed. LeValley (pers. comm.)
reportedseeingabout30 ploverson the lakeon 29 and 30 May 1971, a time
when migrantsshouldhave been absent.Two nestsfound in 1964 (McCaskieand Pugh 1964) are the only previousnestingrecords.
Mono Lake accounted for 20.8% of the adults in the interior and all of the
SnowyPloversin MONO COUNTY. The lake's384 birdsrepresentedthe
state'ssecondlargestconcentration.Birdswere found from Navy Beachon
21
SNOWY
PLOVER
BREEDING
STATUS
the south side counterclockwise
along the shorelineto Black Point on the
north side. A small,isolatedpocketof birdsalsooccurredat Mono County
Park on the northwestsideof the lake. Nestswereon unvegetatedgraveland
sandridgesup to 1.5 km from waterand on dry alkalifiatsas closeas 100 m
to the recedingwater line. In all, 128 nestswere locatedin 1978 (Pageet al.
1979).
No one reportednestingSnowyHoversat Mono Lake before1976 when
Winklet et al. (1977) found 3 nests,at least6 broodsand, on 14 September,
had a highcountof 100 adult-sizedbirdson a censusof the entirelake. Page
and Peasleevisitedthe area for 2 days in mid-June 1977 and found 90
adultsand 8 nestsalong part of the shoreline.
Snowy Hovers occurredat one locationin LASSEN COUNTY, Honey
Lake, where 208 birds made up 11.3% of those in the interior. Most birds
were found alongthe southeastsideof the lake from just southof Wende] to
the baseof a broad peninsulathat bisectsthe southshore,alongthe westside
of that peninsula,and along the north shore of the lake, especiallyin the
vicinityof HartsonReservoir.Becausewe did not coverthe shorelinefrom 3
km eastof HartsonReservoirto 0.8 km southof Wendel, we may have missed
somebirds.The only nestsfoundswere in clumpsof DistichIlsnear Hartson
Reservoir but we suspectbirds also nested on dried, cracked mud several
hundred meters from water on the east side of the lake. We found broods in
all areaswherethere were adults.Priorto our surveythe only recordfor the
Honey Lake area was an observationof two pairs on the floor of Hartson
Reservoiron 11 June 1977 {Gainesfide Jurek pers. comm.).
Four sites,Lower Alkali Lake, Middle Alkali Lake, Upper Alkali Lake and
Goose Lake, in MODOC COUNTY held 391 birds or 21.2% of those in the
interior.By the time we reachedthis area in early July the alkali lakeshad
evaporatedconsiderably,exposingwide expansesof lakebed. On Lower
Alkali Lake, where water coveredabout50 % of the lakebed,all ploverswere
found at the northeastend where open standingwater abutteda marsh.Ten
nests were found in the same area but several hundred meters from the water
on a low plateauborderingthe lakebed.Middle Alkali Lake was nearlydry
but we foundsomeploverswithbroodsby open wateradjoiningmarshnear
the north end of the lakebed. Ploverswere found along the eastside of Upper Alkali Lake where 75% of the lakebedwas stillcoveredby water;there
was no suitableopen habitaton the west side. Some nestsat Upper Alkali
Lake were near the edge of the lakebedon alkaliflat as far as 2-3 km from
water; other nestswere much closerto water. Broods were found by water
mostlyat the northeastend of the lake.Oursarethefirstbreedingrecordsfor
all of the Alkali Lakes.
The 33 adults and 11 broods near water on alkali flats at the southwest end
of Goose Lake, MODOC COUNTY, were the lastploverswe found on the
interior survey. Dawson (1923) reported breedingplovershere in June
1912, providingthe only other record.
Since there was a breedingrecord in the Tule-Lower Klamath Lakes
regionof SlSKIYOU COUNTY in 1957 (Gilesand Crabb1958), we visited
thisarea but found no plovers.It is unlikelythat the speciesbreedsregularly
there, exceptperhapsat White Lake justacrossthe borderin Oregonwhere
we saw a few plovers.JamesHainline, a biologistat Klamath Lake National
22
SNOWY
PLOVER
BREEDING
STATUS
WildlifeRefuge, told us he had seen 8 adultsand 5 chicksat White Lake a
few daysbeforeourvisitin earlyJulybutthathe had notseenSnowyPlovers
on the Californiasideof the refuge.
Inland Habitat
Breeding habitat consistedprimarily of shallow lakes bordered by
unvegetatedor sparselyvegetatedflats.Inhabitedlakeswere distributedover
the lengthof the state,mainlyin the Upper and Lower SonoranLife Zones
(Grinnell 1915); most were alkaline.
Nestsweregenerallylocatedin flat, openareas,althoughmanywerepartly concealedby microhabitat
features.Of 45 nestsat the SaltonSea, Owens
Lake, Honey Lake and the Alkali Lakes, 40% were within 15 cm of
somethingsuchas a stick,rock or clumpof vegetation,even thoughthese
wereusuallyscarcein the generalarea.Exceptfor 11% of the neststhatwere
in fiat (topographic
reliefwithina 1 m radiuslessthan5 cm) areasawayfrom
vegetationor other surface irregularities,the remaining nests were on
substratewith enough topographicrelief or disruptivecoloration (sandpebblesubstrate)
to providesomeconcealment
for the eggsand in many
casesthe incubatingbird.
At inland lakeswe usuallysawbroodsfeedingwithina few metersof the.
water. When disturbedthey often ran acrossdry open flats to avoid us.
Chicksreadily hid in availablemarshvegetation,particularlyat the Alkali
Lakes in Modoc County.
Disturbanceto NestingHabitat
Exceptat RosamondLake, habitatat eachbreedingsitehad apparently
been alteredby human activitiesover the past 200 years.In the Central
Valleyagriculturaldevelopmenthasconfinedwetlandsto suchan extentthat
suitable
breedinghabitatislargelydepleted.The onlyhistorical
nestingsiteof
any sizewe were ableto identify,BuenaVista Lake in Kern County,has
disappeared.At severalbreedingsitesin the Mohave Desertand the Great
Basin, agriculturalor municipalwater demands have altered habitat. The
moststrikingexamples,OwensLake whichhasalmostcompletelydriedup,
andMono Lake whoselevelsarerapidlydropping,heldthe largestconcentrationsof birds.Becausemuchhabitatremainsin theseareasandpractically
nothingisknownaboutbreedingnumberspriorto the 1970s, we refrainfrom
assessing
the effectof thesechangeson the plover.Man'sintervention
at the
Salton Sea has produced breedinghabitat for a substantialnumber of
plovers.Whether the additionalhabitatoffsetsthe lossat other locationsremains unanswered.
We saw nestpredators,particularlyCommon Ravens, at almostall locationssurveyed.One ravenwasseentakingthe eggsof a ploverand thoseof
several American Avocets (Recuruirostraamericana) at Owens Lake. At
Mono Lake CaliforniaGulls, ravensand Coyotes(Canislatrans)destroyed
many plover nests(Page et al. 1979).
23
SNOWY
IV. SEASONAL
JOHN
PLOVER
VARIATION
S. WARRINER
BREEDING
STATUS
IN PLOVER NUMBERS
and JANE C. WARRINER
To help interpretthe resultsof the statewidesurveyswe studiedbreeding
Snowy Ploversat Pajaro Duneson MontereyBay, measuringthe degreeto
which observerscould detect birds on censusesand definingthe species'
migrationperiods.PajaroDunesis a beachfronthousingdevelopmentat the
Pajaro River mouth in extremesouthwesternSanta Cruz County. Plovers
breedon eithersideof the rivermouthand on a smallunvegetatedflat in salt
marsh 1 km away. During I977 and 1978 we tried to find all nests,and at
approximately7 day intervalscountall birdsin the area. Justprior to nesting
in March 1978, 25 adults were individuallycolor banded by placingtwo
stripsof differentlycoloredplastictape on each of two aluminumbands,one
on eachleg. Additionalbirdswere latercapturedon their nestsand similarly
marked. From the time of markingonwardscountsof markedand unmarked
birdsenabled us to use the Lincoln Index [P = (T x M)/N, where P = total
number of ploversin area, T = total number of birdsseen on census,M =
I10-
I00--
90-
8070-
60-
50-
40-
.:50-
I0-
O-
20
29
MARI
6
12
19
APR
26
2
I
I0
17
2430
MAY
7
i
14
21
JUN
305
1014
21
I JUL
Figure la. Number of adult Snowy Ploverscounted(solidbar) and estimated(open
bar) at Pajaro Dunes in the 1978 breedingseason.
24
SNOWY
PLOVER
BREEDING
STATUS
number of marked birds known to be in the area and N - number of marked
birdson census]to estimatethe total number of ploversin the area.
Experiencedobserversconducted19 censusesof ploversin the Pajaro
studyarea betweenMarch and July 1978. The numberof markedplovers
sightedvaried between54% and 91% and averaged72% (s = 9.1%) of
thoseassumedto be presentbecausethey were sightedbeforeand afterthe
census(Figure la). Pajaro Dunes was a difficultarea to surveybecause
ploversmovedbetweenthreeseparateareas.Due to the more difficultthan
averagecensusconditionsat Pajaro,Pageand Stenzel(pers.comm.) believe
that on the coastalsurveyas a whole it waspossibleto detectat least72% of
the ploverspresent.The detectionrate for interiorsitesmay be lower since
nestingareas,up to 3 km wide, were difficultfor two peopleto cover (Page
pers comm.).
It appearsthat mostspringmigrantsand winteringbirdsleft Pajaro Dunes
by early May. Of 19 markeddepartingbirdsmostleftbetween20 Marchand
26 April (Figure lb). Two remained until 2 and 8 May respectivelyand exhibitedsome nestingbehaviorbeforeleaving. Four of the 19 birdsreturned
for briefperiodsduringsummerbeforedepartingagain.Markedbirdsdid not
begin to return in numbersuntil early July (Figure lb). It appearsthat the
most appropriatetime to conductthe statewidesurveyswas May and June
sincethis is the period that migrantsare leastlikelyto be encountered.
Some breedingbirdsmove betweenareasin May and June. For example,
after 14 June 1978 nine ploversfrom failedPajaronestswerefound 6 km to
the southat MossLanding saltworks. At leasttwo of the nine renestedthere.
Two other birdsdispersedeven farther, one turningup 27 km to the northwest at Wilder State Beach and one 75 km northeast at South San Francisco
Bay. Midsummermovementsof breedingbirdsto and from a sitemay vary
annually.In 1977 the breedingpopulationincreasedat Pajaro Dunesfrom
early May to early June and then leveled off. In contrastin 1978 numbers
wererelativelyconstantin May but declinedin June. The aboveexamplesillustratedthat repeatedcensusesof particularbreedingsitesoften produce
variable numbers, hence any singlecensusmay not reflect the maximum
capacityof the area to supportploversthat year.
20-
15-
,o_
ill
o-
MARI
APR
I ! .
I
I
.
MAY
I
JUN
I JUL
Figurelb. Numberof marked,locallynon-breedingSnowyPloverson censuses
at Pajaro Dunes in 1978.
25
SNOWY
DISCUSSION
AND
PLOVER
BREEDING
STATUS
SUMMARY
GARY W. PAGE and LYNNE
E. STENZEL
BreedingSnowy Ploverswere distributedwidelyover the state(Figure2)
but, unexpectedly,
mostwerein the interiorratherthanon the coast(Table
7). Apparentlyfew observershad exploredthe interiorso that the large
numberof birdsthere had escapednoticeuntil this survey. On the coast,
largerconcentrations
of birdswerein the souththanin the north,suggesting
the centerof the species'coastaldistribution
liescloserto the southernthan
the northernboundaryof the state;therefore,Baja Californiamay alsosupport substantial
numbersof breedingbirds.
Throughoutthe stateopennessof habitatseemedto be a key requirement
for nesting.Of 116 nestsobservedon the coastand in the interior,46% were
vegetation-free
withina 10 m radiusand an additional23% lackedvegetation within a 1 m radius.At only 12 nestsdid vegetationcoverexceed 10%
within10 m and at only5 did it exceed10% coverwithin1 m. Ploverswere
absentfrom beachesheavilylitteredwith driftwood.
Accessto water is probably a breeding requirementalthough birds
sometimesnestedhundredsof metersaway when no obstacleprevented
movementsof chicksbetweenthe nestand water. Thusploversnestaround
shallowalkaline lakes where the waterlinemay retreat severalhundred
metersfrom the nest duringthe month betweenthe layingand hatchingof
eggs.
We did not find ploversnestingon bluff-backedbeacheson the mainland
as we did on San Miguel and San Nicolas islands. Island bluff-backed
beacheswith plovershad generousareasof strandwhichwere lightly
vegetatedor were 50% or more coveredby driftwood,kelp, shellsor small
rocks. In contrastthe upper strandon mainlandbluff-backedbeacheswas
generallynarrow,barrenand oftenwashedby the highesttides.
The amount of availablehabitatat any site may vary seasonallyor from
year to year. On the coastwinter stormsregularlyerode beachesand fill
lagoonswith water, thusreducingpotentialbreedinghabitat.Thisreduction
is followedby a slow increasein habitatduringspringand summerwhen
beach width increasesand shrinkingwater levels in the lagoonsexpose
suitablenestingflats.Thisprocessis relatedto the severityof winterstorms,
which variesconsiderablyfrom year to year. Similarly,intensityof winter
rains, in the absence of human induced water diversions, determines
whetherinteriorbreedingareas,suchasshallowalkalinesinks,are dry, partly
filled or flooded to surroundingvegetation.Thus the number of breeding
Snowy Ploversmay change annually or even mid-breedingseason,in
responseto naturalalterationsin habitatavailability.
Humans have altered breedinghabitat, at least on the mainlandcoast.
Some coastalareashave been developedto the extentthat they no longer
supportplovers;at othersdisturbance
probablyreducesbreedingnumbers
and lowersbreedingsuccess.At ZmudowskiState Beachin MontereyCounty the Warriners(unpubl.data) found hatchingsuccessto be much lower
than on undisturbed
saltpan just 1 km away. At Zmudowskisomeeggswere
obviouslypickedup by peopleand otherswereprobablysteppedon. Others
apparentlywere lostto highwindswhen disturbedbirdswere unableto in26
SNOWY
PLOVER
BREEDING
STATUS
cubateand preventtheir eggsfrom beingscatteredand buriedby blowing
sand. In some instanceshumans have enhanced habitat for the species
throughthe construction
of saltevaporatorsin coastalbaysor floodingof dry
interiorareas. However, suchenhancementprobablydoes not compensate
for the degradationof other areas.
Our conclusionsconcerningthe plover'schangein statusover the past
centuryare limitedby the paucityof historicaldata, particularlyfor the interior. Numbershave definitelydeclinedon the coast;the specieswas not
foundbreedingin 33 of the 53 locations
withbreedingrecordspriorto 1970.
•Im•BIGLAGOON
GOOSE
L' (I• 1UPPER
ALK
ALl
L
!
'• '
ß MIDDLE
ALKALI
L
•HUMBOLDT
BAY
AREA
iILOWER
ALKAL
L
• ....
OtONEY
L
_•,PT
REYES
B
•.
\I
s SA,.,,
':RANCISCO
BA•
'-•
WILDER
CRB •'--"•PAJARO
R MOUTH
'k
NUMBER
OFADULT
ß '[11•EMA•'MA
RES
.
i•SANTA
MARIA
R AREA
ßHARPER
L. •
SNOWY
PLOVERSi•FURISI•A-STA
YNEZ
AR.
OROSAMON
DL
'•
I7 -32
ß
•6
2 :ß
,-2
•
II•SAN
NiCOL•AS
IS'•ik
BALTON
SEA
•,
I•N BAN
DIE(SO
CO
•
Figure2. Distribution
of breedingSnowyPloversin Californiafrom 1977-80surveys.
27
SNOWY
PLOVER
BREEDING
STATUS
Table 7. Number of adult Snowy Ploversfound during 1977-80 surveysin California.
Channel Islands
Mainland coast
San FranciscoBay
Estimated Pairs
Total Adults
130
498
261
954
351
Interior
1843
TOTAL
3409
Of the 33 areas28 are not likelyto have regularbreedingpopulationsagain
becausethe habitathasbeendestroyedor humanuseof the areaistoo great.
The greatestlosseshave occurredin southernCaliforniawhere breeding
plovershave vanishedfrompartsof San Diego, Ventura and SantaBarbara
counties,most of Orange County and all of Los AngelesCounty. In all these
areas the plover's absencecan be correlatedwith industrialor residential
developmentand/or heavy recreationaluse of former beachnestingareas.
To the north, such human factorscome into play lessfrequently,although
they may stillhave causeddeclinesin placesaround Monterey Bay, at San
Francisco,at BodegaBay and the north spitof HumboldtBay.
Current emphasison coastaldevelopmentfor recreationby the State of
Californiaprobablymeansa further lossof habitatfor the plover. If no exchangeoccursbetweeninteriorand coastalbreedingpopulations,a subject
currentlyunderinvestigation,
then the statusof coastaland interiorpopulationsmustbe consideredseparately.There may be a greatersurvivalproblem
on the coastif there is no recruitmentfrom the lessdisturbedinteriorbreeding
areas.
Thissurveylocatedthe importantCaliforniabreedingsitesand developed
an indexof the SnowyPlover'sabundanceagainstwhichfuturesurveyscan
be compared. We encourageinterestedpersonsto keep track of breeding
numbersin areasnear them, especiallywhen habitatalterationsare occurring, and to promotethe protectionof importantbreedingsites.
ACKNOWLEDGMENTS
This projectwas supportedby the membersof PRBO; contractsfrom the
California Department of Fish and Game under Federal Aid in Wildlife
RestorationProjectW54R, NongameWildlifeInvestigations;
and donations
from the Union Oil Company Foundation of California. Rita Halbeisen,
DouglasJudell, Lynda Orman, David Shuford, Chris Swarth and Ralph
Widrig helped with the north coastsurvey;Mark Annis, JonathanAtwood,
Anthony Bledsoe, Gilberto Cabrera, Richard Erickson, Alice Fries, Jan
Larsen, Peter Metropulos,Dennis Parker, Evelyn Peaslee,Michael Silbernagle, PhilipUnitt and the Warrinerswith the southcoastsurvey;and Bud
Antonelis,Michael Hill and RobertJackmanwith Channel Island surveys.
28
SNOWY
PLOVER
BREEDING
STATUS
Hal Spear gave major assistance
with field work and the preparationof the
manuscripton the Channel Islands;Alan Craig, Ronald Dow, Paul Kelly,
Jan Larsen, A1 Vail and Nick Whelan assistedin obtainingaccessto the
islands.We thank the many personsin the military,at saltponds, at oil fields,
in the stateand nationalpark servicesand with The Nature Conservancy
who provided us with accessto many restrictedlandsalong the coast.Jane
Gull Mossand RobertPersoniusof the South San FranciscoBay National
WildlifeRefugeand JamesWaltonof the LeslieSalt Companyalsohelped
arrangeaccessfor surveyson restrictedproperties.Volunteerswho contributedto the studiesat PajaroDunesincludedSusanCorbus,DorothyLilly,
Irene Manicci,Randy Morganand Barry Sauppein 1977; SteveAllison,Anthony Bledsoe, Carolyn Frederiksen,Mark and Natalie Hopkins, David
Ramer, Barbara and Chris Swarth in 1978; and Dorothy Hunt, Peter
Metropulos,DennisParker, RobertRamer and Edna Vollmer in bothyears.
Chris and Barbara Swarth, Ralph Widrig, David Bontrager, Lt. R.W.
Cosgriff,Alice Fries, Evelyn Millar, Peter Robinson,Nancy and Hal Spear,
A1Tuckerand John and RickyWarrinergenerouslyextendedhospitalityto
the personsconductingthe coastalsurveys.
Theunpublished
fieldnotes
ofpersons
listed
inAppendix
3, Jonathan
Atwood, Paul Collins,Lee Jones,PaulRoush,J.G. Tyler (suppliedby Robert
Hansen),RuthWilsonand DavidWinklergreatlyaddedto our knowledgeof
the Snowy Plover in Californiaand Oregon. The followingcuratorsand
curatorialassistants
from institutionslistedin Appendix 3 providednestor
egg records: Dana Gardner and Lloyd Kiff (WFVZ), Bonnie Farmer
(NMNH), Henry Pelzl (AMNH), G.D. Alcorn (UPS), LaurenceBinfordand
MatthewLeddy (CAS), Janet Hamher (SBMNH), EugeneCardiff(SBCM),
David Willard (FMNH), C.G. Sibley(PMY), KennethParkes(CMNH), Ned
Johnson (MVZ), Stanley Harris (HSU), Stanlee Miller (CU), David Niles
(DMNH), MorrisWilliams(LSU) and RossJames(ROM). Alan Craigand
Gordon Gould of the CaliforniaDepartmentof Fishand Game helpedinitiateand guidethisstudythroughto itsterminationpoint. Commentsby Jon
Dunn, Jane Church,GordonGould, and JosephJehl, Jr. greatlyimproved
early draftsof this manuscipt.Jane was particularlyhelpfulwith her continous support and encouragementthroughout the entire project. To all
thesepeoplewe extendour gratitudefor makingthe surveya rewardingand
pleasantadventure.
This is Contribution205 of Point Reyes Bird Observatory.
LITERATURE
CITED
American Ornithologists'Union. 1957. Check-listof North American birds. 5th ed.
Am. Ornithol. Union, Baltimore, MD. (0).
Anon. 1971. National shorelinestudy Californiaregionalinventory.U.S. Army
Engineer Div., San Francisco.(0)
Baldridge,A., T. Chandikand D. DeSante.1970. The nestingseason.MiddlePacific
coast region. Aud. Field Notes 24:712-715. (1)
29
SNOWY
PLOVER BREEDING STATUS
Barbour,M.G., T.M. DeJongandA.F. Johnson.1976. Synecology
of beachvegetation alongthe Pacificcoastof the United Statesof America:a firstapproximation. J. Biogeogr. 3:55-69. (2)
Bent, A.C. 1929. Life historiesof North American shorebirds.Order Limicolae (Part
2). U.S. Natl. Mus. Bull. 146. (3)
Booth, E.J. 1926. Observationsin the San FranciscoBay region.Condor 28:271. (4)
Chandik, T. and A. Baldridge.1967. Nestingseason.Middle Pacificcoastregion.
Am. Birds 21:600-603. (5)
Chandik, T. and A. Baldridge.1968. Nestingseason.Middle Pacificcoastregion.
Am. Birds 22:642-646. (6)
Chandik, T. and A. Baldridge.1969. Nestingseason.Middle Pacificcoastregion.
Am. Birds 23:688-693. (7)
Chase, T., Jr. and T. Chandik. 1966. Nestingseason.Middle Pacificcoastregion.
Am. Birds 20:595-598. (8)
Chase, T., Jr. and R.O. Paxton. 1965. Nestingseason.Middle Pacificcoastregion.
Am. Birds 19:574-576. (9)
Cogswell, H.L. 1947. Nestingseason.Southern California region. Aud. Field Notes
1:188-190. (10)
Cutler, B.D. and E.A. Pugh. 1959. Nestingseason.Middle Pacificcoastregion.Aud.
Field Notes 13:450-454. (11)
Dawson, W.L. 1923. The birdsof California. South Moulton Co., San Francisco,pp.
1314-1328. (12)
DeBenedictis,P. and T. Chase,Jr. 1963. Nestingseason.MiddlePacificregion.Aud.
Field Notes 17:480-483. (13)
DeSante,D. and R. LeValley. 1971. The nestingseason.MiddlePacificcoastregion:
Am. Birds 25:899-904. (14)
DeSante, D. and V. Reinsen.1972. The nestingseason.MiddlePacificcoastregion.
Am. Birds 26:897-903. (15)
Fisher,A.K. 1893. Reporton the ornithologyof the Death Valley expeditionof 1891,
comprisingnoteson the birdsobservedin southernCalifornia,southernNevada,
and parts of Arizona and Utah. Pp. 7-158 in No. Am. Fauna 7. (16)
Giles,L.W. and B.H. Crabb. 1958. Snowy Plovernestingon Lower KlamathRefuge,
SiskiyouCounty, California.Condor 60:192. (17)
Gill, R., Jr. 1972. South San FranciscoBay breedingbird survey, 1971. California
Dept. Fish and Game Wildl. Manage. BranchAdmin. Rep. 72-6. (18)
Grinnell, J. 1915. A distributionallist of the birds of California. Pac. Coast Avif. 11.
(19)
Grinnell, J., H.C. Bryant and T.I. Storer. 1918. The game birdsof California.Univ.
California Mus. Vert. Zool., Berkeley. (20)
Grinnell,J and M.W. Wythe. 1927. Directoryto the bird-lifeof the San FranciscoBay
region. Pac. Coast Avif. 18. (21)
Hill, H.M. 1941. Waterfowl breedingrecordsfrom San Bernardinoand Riverside
counties, California. Condor 43:71-72. (22)
Howell, A.B. 1917. Birds of the islandsoff the coast of southernCalifornia. Pac.
Coast Avif. 12. (23)
Jurek,R.M. 1974. Californiashorebird
survey,1969-1974.CaliforniaDept.Fishand
Game Spec.Wildl. Invest.Proj. W-54-R FinalReport.120 pp. (24)
Lamb, C. and A.B. Howell. 1913. Notes from Buena Vista Lake and Fort Tejon.
Condor 15:115-120. (25)
Linton,C.B. 1908. NotesfromBuenaVistaLake, May 20 to June 16, 1907. Condor
10:196-198. (26)
3O
SNOWY
PLOVER
BREEDING
STATUS
McCaskie,G. 1968. Nestingseason.SouthernPacificcoastregion.Aud. Field Notes
22:647-650. (27)
McCaskie, G. 1974. The nestingseason. Southern Pacific coast region. Am. Birds
28:948-951. (28)
McCaskie, G. 1975. The nestingseason.Southern Pacificcoastregion. Am. Birds
29:1029-1036. (29)
McCaskie,R.G. and E.A. Pugh. 1964. Nestingseason.SouthernPacificcoastregion.
Aud. Field Notes 18:534-536. (30)
Meadows. D. 1934. Additional notesfrom Santa Catalina Island. Condor 36:40. (31)
Page, G.W. and L.E. Stenzel,eds. 1979. The breedingstatusof the Snowy Ploverin
California.CaliforniaDept. Fish and Game, Nongame Wildl. Invest. Rep. (32)
Page, G.W., D.W. Winkler and C.W. Swarth. 1979. Breedingsuccessof Snowy
Plovers at Mono Lake, California. U.S. Fish and Wildl. Ref. and Wildl. Res.
Rep. (33)
Pickwell, G. 1930. The length and width of the home of the Snowy Plover. Wren-tit
2:1-2. (34)
Pray. R.H. 1952. Nesting season. Middle Pacificcoast region. Aud. Field Notes
6:297-299.
(35)
Pyle, R.L. and A. Small. 1951. Nestingseason.SouthernPacificcoastregion.Aud.
Field Notes 5:306-309. (36)
Quigley, R., Jr. 1955. Snowy Plover: a photograph. Condor 57:239. (37).
Sibley,C.G. 1952. The birdsof the southSan FranciscoBay region. Publ. by author,
mimeo. 44 + vii pp. (38)
Slobodchikoff,C.N. and J.T. Doyen. 1977. Effectsof Ammophila arenaria on sand
dune arthropod communities. Ecol. 58:1171-1175. (39)
Stager, K.E. 1949. Nestingseason.Southern Pacificcoastregion. Aud. Field Notes
3:252. (40)
Stallcup,R. and J. Winter. 1975. The nestingseason.Middle Pacificcoastregion.
Am. Birds 29:1025-1029. (41)
Tyler, J.G. 1916. Some birdsof the Fresnodistrict,California.Condor 18:194-198.
(42)
Unglish,W.E. 1938. Snowy Plover nestingin Merced County, California. Condor
40:40-41. (43)
Walker, L.W. 1935. On a southern California beach. Bird-Lore 37:119-121. (44)
Wilcox, L.R. 1959. A twenty year banding study of the Piping Plover. Auk
76:129-152. (45)
Willett, G. 1912. Birdsof the Pacificslopeof southernCalifornia.Pac. CoastAvif. 7.
(46)
Willett, G. 1933. A revised list of the birds of southwestern California. Pac. Coast
Avif. 21. (47)
Winkler, D.W., C.P. Weigen,F.B. Engstromand S.E. Burch. 1977. Ornithology.
Pp. 88-113 in An ecologicalstudy of Mono Lake, California. Inst. Ecol. Publ.
12, Univ. California, Davis. (48)
Winter, J. and D. Erickson.1976. The nestingseason.Middle Pacificcoastregion.
Am. Birds 30:996-1001. (49)
Yocom, C.F. and S.W. Harris. 1975. Birds of northwestern California. Humboldt
State Univ., Arcata, CA. 68 pp. (50)
31
SNOWY
PLOVER
BREEDING
STATUS
APPENDIX 1. Surveyresultsand historical
recordsof SnowyPloversbreedingin mainland
California.Locationsare listedfrom southto north, firstalong the coast,then at San Francisco
Bay,andtheninland.UnderSurveyStatustheestimated
numbers
of adults(A) or pairs(P) is
givenunlesshabitatwasnotpresentwhenvisiteddueto erosion,floodingor draining(E), the
habitathadbeendestroyed
or madeunsuitable
by humanactivityor development
(D), apparently suitablehabitatwaspresentbutploverswerenot seen(H), or the areamentionedwasnot
surveyed(W). UnderRecords,the mostconvincing
evidenceof breedingis given,withthe
numberof: adultsreportedduringMayor June(A), pairsreportedin Mayor June(P), females
reportednesting(F),broods(B),chicks(C), ornests(N). An N withouta numberisgivenwhena
sourcemakesa generalreference
to SnowyPloversbreeding.UnderSource,initialsreferto individuals
or institutions
listedin Appendix3, numbersto references
in the literaturecited,andinitialswith numbersto informationfrom museumegg set or specimenrecords.Max. untferEgg
Setsin MuseumEggCollections
isthe maximumnumberof eggsetscollectedduringone5 day
period.
Survey
Egg Setsin
Status
MAINLAND
COAST
San Diego County
Tijuana R Mouth
P 19
Records
Museum Collections
Numbers
Year
Source
N1
1973
KB
N1
1977
PJ
Silver Strand Beach
P 3
N1, B1
1930s
44
SilverStrandBay Shore
San Diego Bay
P3
P 16
N1
1977-78
PJ,DP
A
1973
KB
N2
1975
BM
Salt Works
Sweetwater R Mouth
North Is NAS
LindberghField
Ocean Beach
N20'
1977
PJ
A
1973
KB
A
1977
PJ
H
A20,B5
N2
1978
1979
EC,DP
W
N1
1979
EC,DP
P 9
D
H
Pacific Beach
D
PenasquitosLagoon
H
Del Mar Beach
E,D
San Elijo Lagoon
BatiquitosLagoon
P 12
P3
Agua Hedionda
P 27
Lagoon
Buena Vista Lagoon
32
D
Max.
Years
18
3
1918-1940
3
1
1931-1938
DP
E,D
San Diego: site unk.
MissionBay Beach
MissionBay Fill
Total
N1
1972
SL,LOCU
N1
1977
PJ
N2
1977
PJ
A4
1978
DP
N1
1976
PJ
A18,N1
1970
He
A75,N5
1971
He
A39,N,B5
1978
DP
A9
1973
KB
A60
1975
BM
N2
1977
PJ
B1 ' '
1951
36
None
1977
PJ
5
3
1904-1917
4
1
1894-1938
23
4
1915-1930
4
2
1904-1916
19
8
1922-1954
3
1
1932-1936
SNOWY
PLOVER
BREEDING
STATUS
APPENDIX 1 (Cont.)
Survey
Egg Sets in
Status
Records
Numbers
Oceanside to Santa
P 37
MargaritaR Mouth
French Creek Mouth
P 2
Museum Collections
Year
Source
Total
12
1917-1928
1907-1917
N8
1971
DS,LOCU
N7.
1972
DS, LOCU
N1
1973
N10
1974
DS, LOCU
AF,LOCU
A20,C17
1975
BM
N,C
1977
PJ
Cl
1979
DP
Max.
Years
Orange County
Balboa Beach
D
3
Newport Beach
D
39
1893-1928
HuntingtonState Beach
D
N1
1955
37
21
1917-1940
D
None
1947
10
Bolsa Chica Beach
12
1905-1907
P 10
2
1960-1961
Sunset Beach
D
1
SunsetBeach Bay Fill
H
Bolsa Chica Salt Flats
Anaheim Landing
N1
1970
BM
N2
1971
BM
C1
1973
KB
1916
1907
D
Los AngelesCounty
Redondo
Manhattan
Beach
Beach
24
W
W
N1
1947
10
Playa del Ray
D
N4
1914
3
P. del R. Salt Flats
H
Ballona Beach
D
P50
1903
NMNH
31481
D,W
N6
1938
WFVZ
Santa Monica/Malibu
1
1
46
1894-1904
1914
1923
1894-1904
1895-1947
3497
N1
NiggerSlough
Los Angeles:site unk.
Ventura County
Mugu LagoonSpits
Ormond
Beach
P41
P14
McGrath Lake Beach
P3
Santa Clara R Mouth
P13
Ventura Beach
1949
40
2
W
W
N,C
1973
KB
N1
1976
SW
P15,N1
1977
BM
C1
1975
SW
A30,N6
1975
SW
A25
1976
SW
1895
14
1883-1905
22
1896-1937
1915-1948
D,H
Santa Barbara County
Carpinteria-Sandyland
E,D
Santa Barbara Beach
E,D
N1
1960
FM
25
1909-1946
15
1891-1933
33
SNOWY
PLOVER
BREEDING
STATUS
APPENDIX 1 (Cont.)
Egg Setsin
Survey
Records
Status
Goleta Beach
E,D
Museum Collections
Numbers
Year
Source
Total
Max.
Years
P24
1927
WFVZ
16
3
1927-1948
2
1
1934-1936
18
4
1926-1934
31500
A
1970s
SW
A
1970s
SW
D
N2
1965
LOCU
P40
N1
1974
EJ
C
1977
EJ
GoletaSloughFlats
H
Santa Ynez R Mouth
P5
Purisima Point Beach
P55
South Nipomo Dunes
P4
Santa Maria R Mouth
P18
.SanLuis Obispo County
No. Nipomo Dunes
Pismo Beach
Morro Bay Area
Spit and Beachto N
P2
Monterey County
Point Sur Beach
P2
Pacific Grove
E,D
2
1
1916
Monterey-Seaside
E,D
8
3
1875-1899
24
4
1894-1938
38
8
1895-1948
1S
4
1893-1940
Marina Beach
P12
SalinasR Spit
P16
MossLandingBeach:
(SalinasR-Pajaro R)
MossLanding
P6
P24
Salt Works
B2
1967
5
A
1968
6
A5-16,C0
1972
DPi,15
A50+
1976
SW
N5
1930
34
C1-4,N1
A20,C1
1948-53
1963
VA,35
13
A5,N0,C0
A10,N0,C0
1965
1966
9
8
14
N
1971
B1
1967
5
N1,B2
1954
VA
Santa Cruz County
PajaroR Mouth &
P17
Palm Beach
N7,C14
1972
N7
1973
JW:LOCU
15
N10
1975
41
Santa Cruz Beach
D
5
2
1877-1878
Wood's Lagoon
D
1
1
1876
Moore Cr Mouth
D
1
1
1887
Wilder Cr Mouth
P8
1
1
1929
F2
1922
N
1976
CAS70154,
70155
Four-Mile Beach
34
49
SNOWY PLOVER BREEDING
STATUS
APPENDIX 1 (Cont.)
Egg Setsin
Survey
Records
Status
LagunaCr Mouth
H
Scott Cr Mouth
D
Waddell Cr Mouth
H
Meader's Beach
W
Museum Collections
Numbers
Year
Source
B1
1979
EV
B2
1979
PM
Total
Max.
Years
4
2
1878-1946
1
1
1878
1
1
1905
Son Mateo County
Aria Nuevo Beach
P5
Franklin Point
P
1968
6
C1
1969
7
N
pre-1927
21
N
1975
PM
N1-2
1970s
N1
1967
PL:LOCU
N
1970s
GP,LS
4
E
Pescadero
P2
Marin County
GP,LS
BolinasLagoonSpit
LimantourSpit
P1
P4
DrakesBeachSpit
P1
PointReyesBeach
P15
N1
1926
BodegaHarborSpit
H
C
1960s
GB
Salmon Creek Beach
H
N
1978
DFS
1
1
1920
A
1910s
12
22
2
1899-1948
C2
1976
PK
2
1
1931-1935
1
1
1935
Sonoma County
Mendocino County
MacKerricher Beach
P9
Humboldt County
So. HumboldtBay Spit
Elk R Spit
No. HumboldtBay Spit
LanphereDunes
Mad R Spit
P4
P1
P6
P2
P10
Clam Beach
P1
Carson's
LandingPenin.
Big LagoonBar
H
P8
Del Norte County
Lake Talawa Beach
P3
SmithR Spit
P4
SAN FRANCISCO
P1
1974
50
N15
1971
18
C
1950
38
N3
1959
11
BAY
Santa Clara County
So. San FranciscoBay
Alviso
A14
35
SNOWY
PLOVER
BREEDING
STATUS
APPENDIX 1 (Cont.)
Survey
Egg Sets in
Records
Status
Numbers
Year
Museum Collections
Source
Total
Max.
Years
Son Mateo County
So. San FranciscoBay
A19
Belmont
Bair Island
A2
1972
24
N
1975-76
41,49
A2
1977
TM
Redwood City
1919
Alameda County
So. San FranciscoBay
DumbartonBridge
A318
Hayward
Westof CoyoteHills
Bay Farm Island
Alameda So. Shore
P many
1910s
N
1971
N1
1975
20
14
JA:LOCU
N
1965
9
N1
1972
HP
A1,C1
1974
ER
A8
1977
TM
AS
1979
LF
A2-8
1971-77
ER
A1
1978
ER
N3
1975
RG
N
1933
47
N
1968
27
1971-74
24
N1
1939
22
C1
1940
22
C3
1974
28
A68,N1,B3
1977
PH
N1
1907
26
P
1912
25
A
1912
12
Napa County
Little Is. Evaporator
INTERIOR
OF STATE
Imperial County
Salton Sea
A226
A0-10
1
1929-1950
RiversideCounty
Salton Sea
Lake Elsinore
A10
E
Son Bernardino Count•
Harper Lake
A61
Seaties Lake
A16
Kern County
Rosamond Lake
A6
Koehn Lake
A26
Goose Lake
A2
Buena Vista Lake
D
Kings County
Corcoran Reservoir
Tulare Lake
36
A1
D
2
1
1948
SNOWY PLOVER BREEDING STATUS
APPENDIX 1 (Cont.)
Egg Setsin
Survey
Museum Collections
Records
Status
Numbers
Year
Source
W
P1
1915
42
H
A
1912
12
A
1914
12
N5-6
1937
43
W
C
1963
13
W
B1
1970
1
1974-77
JT
Total
Max.
Years
Madera County
East of Firebaugh
Merced County
Los Banos
4
1
1
1
1937-1939
Yolo County
DavisSewagePonds
Woodland Sewage
Ponds
lnyo County
Tecopa Marsh
Owens Lake
A7
A499
Salt Lake
A1
Tinemaha Reservoir
A2
Deep SpringsLake
A13
Al-12
A"many"
1893
16
A130,C
1975
29
A2
1977
PH
N2
1964
30
A30
1971
RL
N3,B6
1976
48
A90,N8
1977
GP,SP
Mono County
Mono Lake
A384
Butte County
Near Reigo
W
1913
Lassen County
Honey Lake
EagleLake
A208
H
P2
A3
1977
1948
DG
fide DA
A33
A
1912
12
H
N
1957
17
A
1971-73
24
Modoc County
Lower Alkali Lake
A92
Middle Alkali Lake
A36
Upper Alkali Lake
A230
Goose Lake
$iskiyouCounty
Lower KlamathRefuge
' Observerfound total of 20 nestsduringnestingseason;some may have been renests.
"This record is questionableas observerfound a four-chickbrood, which is a very unusualbrood-sizefor
Snowy Plovers.
37
SNOWY
PLOVER
BREEDING
STATUS
APPENDIX 2. Sites not listed in Appendix 1 where apparently suitablehabitat was
surveyedfor breedingSnowy Ploversare listedbelow by county.
ALAMEDA: Alameda Naval Air Station. DEL NORTE: Klamath River mouth,
Crescent Beach, Pebble Beach, Pelican Beach. HUMBOLDT: Mattole River mouth,
McNutt Beach, Eel River spits,Little River spit, Agate Beach, Dry Lagoon bar, Stone
Lagoon bar, FreshwaterLagoon bar, Gold BluffsBeach, CarruthersBeach. KERN:
Rogers Lake, Pazuza Land and Water Company, Kern National Wildlife Refuge.
KINGS: Hanford Sewage Ponds. LASSEN: Eagle Lake, Horse Lake. MADERA:
Madera Lake. MARIN: Cronkhite Beach, Dillon Beach. MENDOCINO: Manchester
Beach, Navarro River mouth. MERCED: Volta Wildlife Area, Santa Fe Grade (road
from Gustineto Los Banos), Merced National Wildlife Refuge. MODOC: Clear Lake.
MONTEREY: Little Sur River mouth, Carmel River mouth, Carmel Beach, Moss
Beach, Spanish Beach, Elkhorn Slough south shore. NAPA: North San Francisco
Bay marshesand saltevaporators.ORANGE: San Juan Creek mouth (DohenyState
Beach), Aliso Beach, Corona del Mar State Beach. RIVERSIDE: San Jacinto Reservoir, Ford Lake, Palen Lake. SAN BERNARDINO: Dale Lake, Danby Lake, Cadiz
Lake, BristolLake, West Cronese Lake, East Cronese Lake, Soda Lake, Silver Lake.
SAN DIEGO: Naval Training Center, San Diego Flood Control Channel, San
DieguitoCreek mouth, CockleburrCanyon mouth, San Onofre Creek mouth, San
Mateo Creek mouth. SAN LUIS OBISPO: CayucosCreek mouth, Villa Creek mouth,
Santa Rosa Creek mouth, San Simeon Creek mouth, Pico Creek mouth, San Simeon
Beach, Soda Lake. SAN MATEO: Half Moon Bay, Linda Mar Beach (San Pedro
Creek mouth). SANTA BARBARA: Devereaux Beach, Devereaux Slough, Bell to
Tecolote Creek mouths, El Capitan Beach, Refugio beach, Gaviota Beach, Canada
de Santa Anita mouth, Arroyo El Bulito mouth, Jalama Beach. SANTA CRUZ:
Seacliff State Beach, Moran Lake, Cocoran Lagoon, Schwans Lagoon, County
Dump Gulch, Major'sCreek mouth, San Vicente Creek mouth, Davenport Landing
Beach. SOLANO: North San Francisco Bay marshes and salt evaporators.
SONOMA: RussianRiver mouth, Gualala River mouth. TULARE: Pixley National
WildlifeRefuge.VENTURA: CalleguasCreek (creekbarsfrom Highway 101 to Lewis
andLasPosasRoads),SilverStrand,Hollywood
Beach,SantaClaraRiverbars(Harbor Blvd. north 8.4 km).
APPENDIX 3. Unpublishedsources of Snowy Plover nest or egg records and
breedingpopulationestimatesfor variouslocations,with abbreviations
usedin Appendix 1 or the text.
Daniel Airola DA, J. Anderson •IA, Vivian Anderson VA, Kristen Bender KB, Gordon
BolanderGB, ElizabethCopper EC, Leora Feeney LF, Alice FriesAF, David Gaines
DG, Robert Gill RG, John and Dorothy Helmer He, Philip Henderson PH, Eric
JohnsonE•J,Paul JorgensenP•J,Paul Kelly PK, Philip Lenna PL, RonaldLeValley
RL, S. ListonSL, FloraMacliseFM, TimothyManoilsTM, BarbaraMasseyBM, Peter
MetropulosPM, Gary Page, GP, Dennis Parker DP, Susan PeasleeSP, Henry Pelzl
HP, DonaldPine DPi, ElsieRoeruerER, David F. ShufordDFS, Lynne StenzelLS,
Dean SwickardDS, •lan Tarhie •JT, •lohn G. Tyler (unpub. field notes)•JGT,Edna
Volliner EV, Jane (Ricky) Warriner •JW, Sanford Wilbur SW.
AmericanMuseumof Natural HistoryAMNH, CaliforniaAcademy of SciencesCAS,
Carnegie Museum of Natural History CMNH, Clemson University CU, Delaware
38
SNOWY
PLOVER
BREEDING
STATUS
Museumof NaturalHistoryDMNH, FieldMuseumof NaturalHistoryFMNH, HumboldtStateUniversity
HSU, Laboratory
of Ornithology,
CornellUniversity
LOCU,
Museum
ofZoology,
Louisiana
StateUniversity
LSU,Museum
ofVertebrate
Zoology,
University
of California
MVZ, National
Museum
of NaturalHistoryNMNH,Peabody
Museum,Yale UniversityPMY, Museumof NaturalHistory,University
of Puget
SoundUPS,RoyalOntarioMuseumROM, SanBernardino
CountyMuseumSBCM,
Santa BarbaraMuseumof NaturalHistorySBMNH, and WesternFoundationof
VertebrateZoologyWFVZ.
Accepted24 January 1981
Publicationof thispaper was made possibleby substantialcontributionsby
Point ReyesBird Observatoryand the CaliforniaDepartmentof Fish and
Game.
-- Editor
Snowy Plover, Mono Lake. California,June 1980.
Photo by lan C. Tait
39
t
.