THE BREEDING
BIRDS
LIFE ON THE ROCK
OF ALCATRAZ
ISLAND:
WILLIAM I. BOARMAN, Department of Biological Sciences, Rutgers University,
Piscataway,New Jersey08854
Grinnell and Wythe (1927) summarizedthe bird life of the San Francisco
Bay region,payingparticularlycloseattentionto distribution
and nestingsites.
However,neithertheirreportnor any othercoveringthe areahasmentioned
the avifaunaof one of the mostprominentand well-knownland featuresin
the region:AlcatrazIsland.The avifaunaof Alcatrazis of interestbecausethe
islandisonly 1.6 km froma largecityanda largenumberof people(anaverage
of 2300 daily, R. Weideman pers. comm.) visit it year round.
Until recently,no ornithologistor naturalhistorianhad visitedor at least
had reportedon any visitsto the island.The onlypublications
on the island's
birdsare by Binford(1980), Howell et al. (1983), and Howell (1983). Here
I summarizemy observations
of the birdsbreedingon Alcatraz.The data are
based on many casual observationsbetween May and August 1981 and
betweenApril and July 1982. All WesternGull nestswere mapped during
this period and on 10 and 30 May 1983.
STUDY
AREA
Alcatrazis an 8.6-ha sandstoneislandin San FranciscoBay and lies4.1 km
east of the Golden Gate Bridge and 1.6 km north of Fisherman'sWharf in
the cityof San Francisco(Figure1). Oblong,the islandrunsnorthwestto southeast and measuresroughly 550 by 200 m. The southwestedge consists
primarilyof sheercliffsrisingto a ratherfiat plateauapproximately
13 m above
water level at the island'snorthwestend and anotherplateau 18.5 m above
waterlevelat the southeastend. The northeastedge risesmore slowlyto a
higherplateau 40 m abovewater level. The plateausare coveredwith concrete,abandonedbuildings,rubbleof demolishedbuildings,bare dirt, and in
some placesgrassor thick vegetation.
Floristically
the islandis disturbed.Originallyit wassolid"sandstone
covered
with a thin coatingof guano"(U.S. Army 1879, cited in Thompson 1979)
devoidof shrubsandtrees.Duringthe late 1800sdirtbroughtoverfromnearby
AngelIslandfor gunbatteryeraplacements
probablycontainedseedsof various
nativeshrubsand annualsincludingDwarf CoyoteBush(Baccharis
pilularis),
CaliforniaPoppy(Eschscholzia
californica),and CaliforniaBlackberry(Rubus
vitifolius),which have since colonizedAlcatraz. After the mid-1860s several
ornamentalplantswereintroduced.Thoseprevalenttoday includeeucalyptus
(Eucalyptussp.), MontereyCypress(Cupressusmacrocarpa),Century Plant
(Agave americana),Nasturtium(Tropaeolummajus), and fuchsia (Fuchsia
hybrida).Since 1963 the plantshave been left untendedand are now growing
virtuallywild.
The islandhasbeen usedheavilyby man since 1853 when a lighthouse
waserected.Sincethen it hasbeen usedas a fort, militaryprison,and, until
1963, as a UnitedStatesFederalPenitentiary.
Todaythe penitentiaryisclosed
and the islandis administered
by the NationalParkServiceaspart of Golden
Western Birds 20:19-24,
1989
19
BREEDING BIRDS OF ALCATRAZ
Gate NationalRecreationArea, attractingan averageof 2300 touristsdaily.
Peopleare allowedto wanderfreelyover certainportionsof the island,but,
onlyparkpersonnel
arecurrenfiy
permittedin theareasinhabited
bymostbirds.
BREEDING
BIRDS
Black-crownedNight Heron (Nycticoraxnycticorax).Roostsand nestsin
eucalyptusand cypresseson the northeastside of islandand in shrubson
northeastandsouthwest
sides.Twenty-four
nestslocatedin 1981, 39 in 1982;
somenestsmayhavebeenoverlookedamidthickfoliage.In 1982 birdswere
firstobservedon 28 February(J. Bartonspers. comm.), and the firstchick
was heard callingfrom the tall cypressesnortheastof the Cell House on 6
April.One presumably
second-year
bird(brown-tinged
plumage)successfully
nestedin 1982. Ray Pierotti (pers.comm.) reportsthe populationto be
expanding.
Mallard(Anasplat•rh•nchos).One or two pairsbred eachyear. Females
havebeenseenwithchickson mostof the island,eveninsidebuildings.One
oldnestwitheggshellfragments
wasfoundundera smallshrubimmediately
southwest of the Cell House.
Heermann'sGull (Larusbeermanni). A pair attemptedto nesteachspring
1979 to 1981 but were unsuccessful
(Howellet al. 1983). The nestwaslocated
under a Dwarf Coyote Bushon an exposedpoint near the incinerator.The
specieshas attemptedno nestssince.
WesternGull (Larusoccidentalis).Nestson exposedcliffs,buildingroofs,
fiatcementslabswithand withoutgrasscover,withindebrisof felledbuildings,
on top of guardtowers,and insidean old washingmachine.Most avoidthe
northeastsideof islandwherethe majorityof humanactivityis. In 1981 a
minimumof 135 pairsbred;in 1982 censusesindicated224 breedingpairs;
in 1983 on two visits126 activenestswere located;however,the secondvisit
wason 30 May, probablybeforeall broodshad beeninitiated(in 1982, only
74% of all nestshadyet beenlocatedby 27 May). RayPierotti(pers.comm.)
reportedthe populationto containover 350 breedingpairsin 1988.
PigeonGuillemot(Cepphuscolurnba).Severaltimesduringthe summer
of 1981 I sawPigeonGuillemotsflyingfrom cliffsalongthe southwestedge
of theisland.Duringa boattriparoundtheislandon 7 JulyI sawtwoguillemots
on the water. More thoroughobservations
were made during 1982. On 22
May and 15 June I flusheda guillemotfrom the cliffwestof the fallenremains
of the apartments.On 15 June two adults,one with a fish in its bill, were
in the waterbelow.Duringthe following15 minutesthe birdcarryingthe fish
flew towardthe cliffthen turned away severaltimes. Finally,it landed on a
smallrockledge2 m fromthe top of the cliffand about 13 m abovethe water
and stuckitshead into a crevice.It retracteditshead a momentlater, without
the fish,and flew backto the water.I climbeddown the cliffand found a crevice
amongthree largerocksthat werepart of an old retainingwall. The roughly
triangularentrancewas approximately10 cm acrossat the base by 18 cm
high. At a depth of 20 cm the cavitymade a turn to the right. I did not see
or hear any chicksbut found at the entrancea brokenegg shell (similarto
PigeonGuillemoteggsin the collection
at the CaliforniaAcademyof Sciences).
Duringmy inspectionof the nestsitethere werethreeguillemotsin the water
2O
BREEDING
BIRDS
OF ALCATRAZ
Figure1. AlcatrazIsland,showingall buildingsmentionedin the text.
21
BREEDING
BIRDS
OF ALCATRAZ
below,one givingan alarm "scream"(Nelson1985) and two with fishin their
bills.On 25 June, Paul Jones (pets.comm.) saw one slate-blackchickwith
dark legsfar backin the crevice.He found the remainsof two dead fish (one
a midshipman,Porichthys
sp.)on the ledgeimmediatelyoutsidethe opening.
I foundonlythisone neston AlcatrazbutsawI5 to 20 birdsbegging,calling,
carryingfish, flyingin "figure-eight"patterns,and sittingon the cliffsor in
crevicesand holes,suggesting
that as manyasten morenestsmay havebeen
present. Island-basedobservationson I8 June, 25 June, and 8 July I982
revealedfive possiblenestinglocations:southand westof the shop building,
southeastend of Baker Beach, 75 m southeastof this last site, north of the
incinerator,and immediately west of the incinerator.
On 13 July I982, duringa surveyby boat, I sawseveralguillemots,three
of whichwerebegging,alongthesouthwest
cliffs.Threebirdswereseensitting
in smallman-madeholesboredin rockapproximately6 m abovethe water,
two near the industriesbuildingand one 75 m southeastof Baker Beach.
These,and a fourthunoccupiedhole at the southeastcornerof BakerBeach,
had fair amountsof guano belowthem and may have been nestingholes.
I sawa guillemotperformthe "figure-eight"
flight,thenlandby a crevicenext
to another bird southwest of and well below the verified nest. Six birds were
seen sittingquietlyon the cliff west of the incinerator.This is the firsttime
guillemots
havebeenknownto nestwithinSanFrancisco
Bay (seeSowlset ai.
1980).
The lackof previousrecordsof PigeonGuillemotsbreedingin SanFrancisco
Bay indicatesthatthisis mostlikelya newlyformedcolony.Twofactorsmay
havecontributed
to the coiony'sestablishment.
The NationalParkServicecurrentlyrestrictspublicaccessto certainpartsof the island,leavingthe nesting
birdsrelativelyundisturbed
by people.An increasein populationsizeat other
coloniesmay have increasedcompetitionfor nestingsites,promptingsome
birdsto pioneernew colonies.In supportof this,populationsizeat the South
FarallonIslandscolonydid increasein the late seventiesand early eighties
(D. E DeSantepets.comm.).Furthermore,DeSanteand Ainley(I980) suggestedthat the Farallonguillemotpopulationreachedsaturationin the late
seventies.PigeonGuillemotswerestillvisitingAlcatrazdailyduringthe 1983
through I988 breedingseasons(R. Pierottiand J. Howell pets. comm.).
SongSparrow(Melospizamelodia).I foundapproximately
sixsingingmales
in heavilyvegetatedareasthroughoutislandbut saw no nestsor young.
White-crownedSparrow (Zonotrichiaieucophrys).I found one nest with
young on 14 June 1981. Approximately14 singingmales are distributed
throughoutthe island.If the birdsoccupythe entireislandand territoriesare
contiguous,the averageterritorysizeis 0.6 ha. Luis Baptista(pers.comm.)
hasrecordedsongsfrom 12 individuals.
He notedthattheirsong-typeisdistinct
from that of neighboringislandsand may havebeen derivedfrom the Marin
dialect.
In addition,the followingspeciesnestingon the nearbymainlandremained
throughthe breedingseasonon Alcatraz,thoughI did not see them nesting
there.Courtshipbehaviorwasobservedoftenamongthefourto sixRockDoves
(Columbia livia) present. One or two Mourning Doves (Zenaida macroura)
were frequentlyobservedin and around the tall treesnortheastof the Cell
House. Two to three Anna's Hummingbirds(Calypte anna) and Allen's
22
BREEDING
BIRDS OF ALCATRAZ
Hummingbirds
(Selasphorus
sasin)weremostoftenseenin heavilyvegetated
areasalongthe northeast
sideof island.One BlackPhoebe(Sayorals
nigricans)
wasusuallyon the docksouthwest
of Building64 or nearthe ModelIndustries
Building.A pair of BarnSwallows(Hitundorustlea)wasseenoftenin 1981
nearthe dockandaroundBuilding64, wheretheymayhavenested(S. Paris
pets.comm.). Approximately12 EuropeanStarlings(Sturnusvulgaris)were
usuallyseenin a flockovertheentireisland.Onepairof PineSiskins(Carduelis
pinus)wasactivein 1982 in the treeseastof the Cell House.TwoHouseFinch
(Carpodacus
mexicanus)
flocks,eachof 8 to 10 individuals,
wereseenin the
area around the water tower and west of the Cell House.
DISCUSSION
In all, five specieswere known with certaintyto have successfully
bred on
AlcatrazIsland(Black-crowned
Night Heron, Mallard,WesternGull, Pigeon
Guillemot,White-crownedSparrow). Another specieshas made an unsuccessfulattemptto breed (Heerman'sGull). A seventhspecies(SongSparrow)
most likely breedson the islandbut nestshave yet to be found. Nine other
specieshaveremainedthroughthe breedingseasonbut havenot been seen
nesting(RockDove,MourningDove,Anna'sHummingbird,Allen'sHummingbird,BlackPhoebe,Barn Swallow,EuropeanStarling,Pine Siskin,and House
Finch).Additionally,R. Pierottiand C. Christensen(pets.comm.)believethat
a pair of CommonRavens(Corvuscorax)probablynestedon the southend
of the island in 1988.
The breedingbirdsof the South FarallonIslandshave been discussed
by
DeSante and Ainley (1980). Of the twelve seabirdspeciesthat breedon the
Farallones,only two (WesternGull and PigeonGuillemot)neston Alcatraz.
Remarkably,the two islandsshareno known speciesof breedinglandbirds.
Of the all the speciesnestingon the Farallones,the House Sparrowis the
most curiousfor not nestingon Alcatraz. I have no explanationfor this
phenomenon.
Of the 101 specieswhich have been seen on or near Alcatraz(pets.obs.;
S. Abhors,I. Bletz,M. Flippo,S. Paris,pets.comm.) a maximumof 16 may
have attemptedto breed during 1981 and 1982. My resultscan be used as
a baselinefor trackingfuturetrendsin populationsizesand will facilitatethe
correlationof thesetrendswith environmentalevents (e.g., pollutantsand
weatherpatternssuchas El Nifio). The bird populationson AlcatrazIsland
may alsoprovideresearchopportunities.The NationalParkServicehasprotectedmostof the breedingareasbut is now consideringplansto open most
of the islandto visitors(J. Howell and R. Weidemanpets.comm.).The White-
crownedSparrowpopulation
isisolated
enoughthatit hasitsownsongdialect
(or subdialect)and smallenoughthat the entirepopulationcouldbe studied
easily. There are no mammal predators,an uncontrollablefactor on the
mainlandand many other islands.The other islandsin San FranciscoBay
provide the opportunityfor comparativestudies.
Finally,Alcatrazisa valuablenaturalresource.
It hasthethirdlargestcoastal
colonyof WesternGulls in centralCalifornia(Sowlset al. 1980), the only
colonyof PigeonGuillemotsin San FranciscoBay, and a breedingpopula-
tion of Black-crowned
Night Herons.I hope that a betterunderstanding
of
23
BREEDING
BIRDS
OF ALCATRAZ
the birdson AlcatrazIslandand theirinteractionswith other localpopulations
will help to eliminate activitiesand future developmentsthat would be
hazardous to them.
ACKNOWLEDGMENTS
I thank Judd Howell and Rich Weideman of the Nal•onal Park Service for his valuable
logisl•calsupportduringthe courseof thisstudy.My wife, JeanieA. Mlenar,assisted
with the field work. Jan Barrons,Chris Christensen,Bob Crabb,Paul Jones,Molly
O'Malleyand SharonParisprovidedvaluableobservations.
PaulJonescrawleddown
the steepclifffacewithloosestoneswhileholdingontoan oldpieceof cablefor support
to get a look insidethe nestcavity.RobertBowman,DavidE DeSante,Judd Howell,
PaulJones,JosephMorlan,DouglasNelson,andRaymondPierottimadevaluablecommentson early versionsof the manuscript.
LITERATURE
CITED
Binford,L. C. 1980. Heermann'sGull invadesAlcatraz.PointReyesBird Observatory
Newsl. 51:3.
DeSante,D. E, and Ainley,D. G. 1980. The avifaunaof the SouthFarallonIslands,
California. Studies Avian Biol. 4:1-101.
Grinnell,J., and Wythe, M. W. 1927. Directoryto the bird-lifeof the San Francisco
Bay region.Pac. Coast Avifauna18.
Howell, J. A. 1983. Heermann'sGull (LarusheermannOon AlcatrazIsland in Golden
Gate RecreationArea, California.Proc.FirstBiennialConf. Res.Calif. Natl. Parks
1:230-233.
Howell, J. A., LaClergue,D., Paris, S., Boarman, W. I., DeGange, A. R., and
Binford,L. C. 1983. Firstnestsof Heermann'sGull in the United States.W. Birds
14:39-46.
Nelson,D. A. 1985. The syntacticand semanticorganizationof PigeonGuillemot
(Cepphuscolumba)vocalbehavior.Z. Tierpsychol.67:97-130.
Sowls,A. L., DeGange,A. R., Nelson,J. W., andI.ester,G. S. 1980. Catalogof California
seabirdcolonies.FWS/OBS 37/80, U.S. Dept. Interior,Fishand WildlifeService.
Thompson,E. N. 1979. The rock:A historyof AlcatrazIsland,1847-1972. Historic
ResourceStudy, Golden Gate NationalRecreationArea, California.U.S. Dept.
Interior, Natl. Park Service, Historic PreservationDivision, Denver.
Accepted 19 December 1988
24
The following articleis the fourth in a serieson Californiararitiesedited by
Morlan and Roberson. It is based on materialssubmittedto the California
Bird Records Committee (CBRC). The descriptionand circumstanceswere
drawn •rom the accountsof the observerand have been reviewed by him.
Robersonprepared the distributionalsummary; Morlan prepared the identificationsummary. In this way we hope much important informationaccumulated in CBRC files wiI] become widely available.
White-collared
FIRST
Swift
RECORD
Sketch by Tim Manoils
OF THE WHITE-COLLARED
SWIFT
IN CALIFORNIA
RICHARD A. ERICKSON, P. O. Box 523, Bayside,California95524
JOSEPH MORLAN, 417 Talbot Ave., Albany, California94706
DON ROBERSON, 282 Grove Acre Ave., Pacific Grove, California 93950
At midmorningon 21 May 1982, Ericksonand his birdingcompanions
Lynn C. Berner, Gary S. Lester,Gary J. Strachan,and RichardS. Tryon
werenearthe sprucegroveat PointSt. George,Del Norte County,extreme
northwesternCalifornia,when a swiftcaughttheir attention.Erickson's
first
impressionwas of BlackSwift Cypseloidesniger, but Strachannoted white
on its neck;soonthe whole groupfocusedon the bird. It wasa largeswift
with tatteredprimariesthat fed with a flock of swallows,includingBarn
Hirundo rustica,Cliff H. pyrrhonota, Tree Tachycinetabicolor, and Violet•reen T. thalassinaswallows,over the õrassyheadland northeastof the
spruceõrove.The morninõfoõwasbreakinõup and liõhtinõconditionswere
õood.The observers
watchedthebirdwithbinoculars
and a 20 x telescope,
as it approachedthem sometimesto within 15 m, for 20 to 40 minutes.The
swiftfed from a heightof 100 m to within8 m of the ground.The following
descriptionis paraphrasedfrom Erickson'sfield notes:
A swiftof typicalshape (slimbody with extremelylong wingsand apparentlyno
"wrists")with a tiny bill and a slightlyforkedtail of moderatelength.It absolutely
dwarfedevery swallowin association,
even at greatdistances.It was substantially
longerthan a Cliff Swallowseenin directcomparison.Gary Lesterfelt the wingspan
wasdoublethat of a Barn Swallow;I thoughtit wasmaybenot quitetwiceas much.
The plumagewas entirelyblackishexceptfor a conspicuous
completewhite collar,
narrowestand cleanestacrossthe napebut broaderand lessdistinctand descending
posteriorlysomewhatacross.thebreast.Thiscollar,especiallyon the nape, wasvisible
Western Birds 20:25-31, 1989
25