THE BREEDING BIRDS OF ALCATRAZ : LIFE ON THE ROCK

WILLIAM I. BOARMAN, Department of Biological Sciences, Rutgers University, Piscataway,New Jersey 08854

Grinnell and Wythe (1927) summarizedthe bird life of the Bay region,paying particularly close attention to distributionand nestingsites. However,neither their report nor any othercovering the area has mentioned the avifaunaof one of the most prominentand well-knownland featuresin the region:. The avifaunaof Alcatrazis of interestbecause the islandis only 1.6 km from a largecity and a largenumber of people(an average of 2300 daily, R. Weideman pers. comm.) visit it year round. Until recently,no ornithologistor naturalhistorian had 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 observationsof the birdsbreeding on 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 sandstoneisland in San FranciscoBay and lies4.1 km east of the Bridge and 1.6 km north of Fisherman'sWharf in the cityof San Francisco(Figure 1). Oblong,the islandruns northwest to south- east and measuresroughly 550 by 200 m. The southwestedge consists primarilyof sheercliffs rising to a ratherfiat plateauapproximately 13 m above water level at the island'snorthwest end and anotherplateau 18.5 m above water level at the southeastend. The northeastedge risesmore slowlyto a higherplateau 40 m above water level. The plateausare coveredwith con- crete,abandoned buildings, rubble of demolishedbuildings, bare dirt, and in some placesgrass or thick vegetation. Floristicallythe islandis disturbed.Originally it wassolid "sandstone covered with a thin coatingof guano" (U.S. Army 1879, cited in Thompson 1979) devoidof shrubsand trees. During the late 1800sdirt brought over from nearby AngelIsland for gunbattery eraplacements probably contained seeds of various nativeshrubs and annualsincluding Dwarf CoyoteBush (Baccharispilularis), CaliforniaPoppy (Eschscholziacalifornica), and CaliforniaBlackberry (Rubus vitifolius),which have since colonizedAlcatraz. After the mid-1860s several ornamentalplants were introduced.Those prevalent today includeeucalyptus (Eucalyptussp.), MontereyCypress (Cupressus macrocarpa), Century Plant (Agave americana), Nasturtium (Tropaeolummajus), and fuchsia (Fuchsia hybrida).Since 1963 the plantshave been left untendedand are now growing virtuallywild. The islandhas been used heavilyby man since 1853 when a lighthouse waserected. Since then it hasbeen usedas a fort, militaryprison, and, until 1963, as a UnitedStates Federal Penitentiary. Today the penitentiaryis closed and the islandis administeredby the NationalPark Service as part of Golden Western Birds 20:19-24, 1989 19 BREEDING BIRDS OF ALCATRAZ

Gate NationalRecreation Area, attractingan averageof 2300 touristsdaily. Peopleare allowedto wanderfreely over certainportions of the island,but, onlypark personnel are currenfiy permitted in the areasinhabited by most birds.

BREEDING BIRDS

Black-crownedNight Heron (Nycticoraxnycticorax). Roosts and nestsin eucalyptusand cypresseson the northeastside of island and in shrubson northeastand southwestsides. Twenty-four nests located in 1981, 39 in 1982; somenests may havebeen overlooked amid thick foliage. In 1982 birdswere firstobserved on 28 February(J. Bartonspers. comm.), and the firstchick was heard callingfrom the tall cypressesnortheast of the Cell House on 6 April.One presumablysecond-year bird (brown-tinged plumage) successfully nestedin 1982. Ray Pierotti (pers. comm.) reportsthe populationto be expanding. Mallard(Anas plat•rh•nchos). One or two pairsbred each year. Females havebeen seen with chicks on mostof the island,even insidebuildings. One old nestwith egg shell fragments was found under a smallshrub immediately southwest of the Cell House. Heermann'sGull (Larusbeerman ni). A pair attemptedto nesteach spring 1979 to 1981 but were unsuccessful(Howell et al. 1983). The nest waslocated under a Dwarf Coyote Bushon an exposedpoint near the incinerator.The specieshas attempted no nestssince. WesternGull (Larusoccidentalis). Nests on exposedcliffs, building roofs, fiatcement slabs with and withoutgrass cover, within debris of felledbuildings, on top of guardtowers, and insidean old washingmachine. Most avoidthe northeastside of islandwhere the majorityof human activityis. In 1981 a minimumof 135 pairsbred; in 1982 censusesindicated 224 breedingpairs; in 1983 on two visits126 activenests were located;however, the secondvisit wason 30 May, probablybefore all broodshad beeninitiated (in 1982, only 74% of all nestshad yet beenlocated by 27 May). Ray Pierotti(pers. comm.) reportedthe populationto containover 350 breedingpairs in 1988. PigeonGuillemot (Cepphus colurnba). Several times duringthe summer of 1981 I sawPigeon Guillemots flying from cliffsalong the southwestedge of the island.During a boattrip around the islandon 7 JulyI sawtwo guillemots on the water. More thoroughobservations were made during 1982. On 22 May and 15 June I flusheda guillemotfrom the cliffwest of the fallenremains of the apartments.On 15 June two adults,one with a fish in its bill, were in the waterbelow. During the following15 minutesthe birdcarrying the fish flew towardthe cliffthen turned away severaltimes. Finally,it landed on a smallrock ledge 2 m from the top of the cliffand about 13 m abovethe water and stuckits head into a crevice.It retractedits head a moment later, without the fish, and flew back to the water. I climbeddown the cliffand found a crevice amongthree largerocks that were part of an old retainingwall. The roughly triangularentrance was approximately10 cm acrossat the base by 18 cm high. At a depth of 20 cm the cavity made a turn to the right. I did not see or hear any chicksbut found at the entrancea brokenegg shell (similarto PigeonGuillemot eggs in the collectionat the CaliforniaAcademy of Sciences). Duringmy inspectionof the nestsite there werethree guillemotsin the water

2O BREEDING BIRDS OF ALCATRAZ

Figure1. AlcatrazIsland, showing all buildingsmentioned in the text. 21 BREEDING BIRDS OF ALCATRAZ below,one givingan alarm "scream"(Nelson 1985) and two with fishin their bills.On 25 June, Paul Jones (pets. comm.) saw one slate-blackchick with dark legsfar back in the crevice.He found the remainsof two dead fish (one a midshipman,Porichthys sp.) on the ledgeimmediately outside the opening. I foundonly this one neston Alcatrazbut saw I5 to 20 birdsbegging, calling, carryingfish, flying in "figure-eight"patterns, and sittingon the cliffsor in crevicesand holes,suggesting that as manyas ten morenests may havebeen present. Island-basedobservations on I8 June, 25 June, and 8 July I982 revealedfive possiblenesting locations: south and 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 saw severalguillemots, three of whichwere begging, along the southwestcliffs. Three birds were seen sitting in smallman-made holes bored in rockapproximately 6 m abovethe water, two near the industriesbuilding and one 75 m southeastof Baker Beach. These,and a fourthunoccupied hole at the southeastcorner of Baker Beach, had fair amountsof guano belowthem and may have been nestingholes. I sawa guillemotperform the "figure-eight"flight, then landby a crevicenext to another bird southwest of and well below the verified nest. Six birds were seen sittingquietly on the cliff west of the incinerator.This is the first time guillemotshave been known to nestwithin San FranciscoBay (seeSowls et ai. 1980). The lackof previousrecords of PigeonGuillemots breeding in indicatesthat this is mostlikely a newlyformed colony. Two factors may havecontributed to the coiony'sestablishment. The NationalPark Service cur- rentlyrestricts public access to certainparts of the island,leaving the nesting birdsrelatively undisturbed by people.An increasein populationsize at other coloniesmay have increasedcompetition for nestingsites, prompting some birdsto pioneernew colonies.In supportof this,population size at the South FarallonIslands colony did increasein the late seventiesand early eighties (D. E DeSantepets. comm.). Furthermore, DeSante and Ainley (I980) sug- gestedthat the Farallonguillemot population reached saturationin the late seventies.Pigeon Guillemots were stillvisiting Alcatraz daily during the 1983 through I988 breedingseasons (R. Pierottiand J. Howell pets. comm.). Song Sparrow(Melospiza melodia). I found approximatelysix singingmales in heavilyvegetated areas throughout island but saw no nestsor young. White-crownedSparrow (Zonotrichiaieucophrys). I found one nest with young on 14 June 1981. Approximately 14 singingmales are distributed throughoutthe island.If the birdsoccupy the entireisland and territoriesare contiguous,the averageterritory size is 0.6 ha. Luis Baptista(pers. comm.) hasrecorded songs from 12 individuals.He notedthat their song-type is distinct from that of neighboringislands and may have been derivedfrom the Marin dialect. In addition,the followingspecies nesting on the nearbymainland remained throughthe breedingseason on Alcatraz,though I did not see them nesting there.Courtship behavior was observed often among the fourto sixRock Doves (Columbia livia) present. One or two Mourning Doves (Zenaida macroura) were frequentlyobserved in and around the tall trees northeastof the Cell House. Two to three Anna's Hummingbirds (Calypte anna) and Allen's 22 BREEDING BIRDS OF ALCATRAZ

Hummingbirds(Selasphorus sasin) were most often seen in heavilyvegetated areasalong the northeastside of island.One BlackPhoebe (Sayorals nigricans) wasusually on the docksouthwest of Building64 or nearthe ModelIndustries Building.A pair of Barn Swallows(Hitundo rustlea) was seen often in 1981 nearthe dockand aroundBuilding 64, wherethey may havenested (S. Paris pets.comm.). Approximately12 EuropeanStarlings (Sturnus vulgaris) were usuallyseen in a flockover the entireisland. One pairof PineSiskins (Carduelis pinus)was active in 1982 in the treeseast of the Cell House.Two House Finch (Carpodacusmexicanus) flocks, each of 8 to 10 individuals,were seen in the area around the water tower and west of the Cell House.

DISCUSSION

In all, five specieswere known with certaintyto have successfullybred on AlcatrazIsland (Black-crownedNight Heron, Mallard,, , White-crownedSparrow). Another specieshas made an unsuc- cessfulattempt to breed (Heerman'sGull). A seventhspecies (Song Sparrow) most likely breedson the island but nestshave yet to be found. Nine other specieshave remainedthrough the breedingseason but have not been seen nesting(Rock Dove, Mourning Dove, Anna's Hummingbird, Allen's Humming- bird, BlackPhoebe, Barn Swallow,European Starling, Pine Siskin,and House Finch).Additionally, R. Pierottiand C. Christensen(pets. comm.) believethat a pair of CommonRavens (Corvus corax) probably nested on the southend of the island in 1988. The breedingbirds of the South FarallonIslands have been discussedby DeSante and Ainley (1980). Of the twelve seabirdspecies that breed on the Farallones,only two (WesternGull and PigeonGuillemot) nest on Alcatraz. Remarkably,the two islandsshare no known speciesof breedinglandbirds. Of the all the speciesnesting on 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 trackingfuture trends in populationsizes and will facilitatethe correlationof these trends with environmentalevents (e.g., pollutantsand weather patternssuch as El Nifio). The bird populationson AlcatrazIsland may alsoprovide research opportunities. The NationalPark Service has pro- tectedmost of the breedingareas but is now consideringplans to open most of the islandto visitors(J. Howell and R. Weidemanpets. comm.). The White- crownedSparrow population is isolated enough that it hasits own song dialect (or subdialect)and smallenough that the entirepopulation could be studied easily. There are no mammal predators, an uncontrollablefactor on the mainlandand many other .The other islandsin San FranciscoBay provide the opportunityfor comparativestudies. Finally,Alcatraz is a valuablenatural resource. It hasthe thirdlargest coastal colonyof WesternGulls in centralCalifornia (Sowls et al. 1980), the only colonyof PigeonGuillemots in San FranciscoBay, and a breedingpopula- tion of Black-crownedNight Herons.I hope that a betterunderstanding of 23 BREEDING BIRDS OF ALCATRAZ the birdson AlcatrazIsland and their interactionswith 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•calsupport during the courseof this study.My wife, JeanieA. Mlenar,assisted with the field work. Jan Barrons,Chris Christensen,Bob Crabb,Paul Jones, Molly O'Malleyand SharonParis provided valuable observations. Paul Jones crawled down the steepcliff face with loose stones while holding onto an oldpiece of cablefor support to get a look insidethe nestcavity. Robert Bowman, David E DeSante,Judd Howell, PaulJones, Joseph Morlan, Douglas Nelson, and Raymond Pierotti made valuable com- mentson early versionsof the manuscript.

LITERATURE CITED

Binford,L. C. 1980. Heermann'sGull invadesAlcatraz. Bird Observatory Newsl. 51:3. DeSante,D. E, and Ainley,D. G. 1980. The avifaunaof the SouthFarallon Islands, . Studies Avian Biol. 4:1-101. Grinnell,J., and Wythe, M. W. 1927. Directoryto the bird-lifeof the San Francisco Bay region.Pac. Coast Avifauna 18. Howell, J. A. 1983. Heermann'sGull (LarusheermannO on AlcatrazIsland in Golden Gate RecreationArea, California.Proc. First Biennial Conf. 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. Firstnests of Heermann'sGull in the .W. Birds 14:39-46. Nelson,D. A. 1985. The syntacticand semanticorganization of PigeonGuillemot (Cepphuscolumba) vocal behavior. 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,Fish and WildlifeService. Thompson,E. N. 1979. The rock:A historyof AlcatrazIsland, 1847-1972. Historic ResourceStudy, Golden Gate National RecreationArea, California.U.S. Dept. Interior, Natl. Park Service, Historic PreservationDivision, Denver. Accepted 19 December 1988

24 The following articleis the fourth in a serieson Californiararities edited by Morlan and Roberson. It is based on materialssubmitted to 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 iden- tificationsummary. In this way we hope much important informationac- cumulated in CBRC files wiI] become widely available.

White-collared Swift Sketch by Tim Manoils

FIRST RECORD OF THE WHITE-COLLARED SWIFT IN CALIFORNIA

RICHARD A. ERICKSON, P. O. Box 523, Bayside,California 95524 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 were near the sprucegrove at PointSt. George,Del Norte County,extreme northwesternCalifornia, when a swiftcaught their attention.Erickson's first impressionwas of Black Swift Cypseloidesniger, but Strachannoted white on its neck; soonthe whole groupfocused on the bird. It was a largeswift with tatteredprimaries that fed with a flock of swallows,including Barn Hirundo rustica,Cliff H. pyrrhonota, Tree Tachycinetabicolor, and Violet- •reen T. thalassinaswallows, over the õrassyheadland northeastof the spruceõrove. The morninõfoõ wasbreakinõ up and liõhtinõconditions were õood.The observerswatched the birdwith binoculars 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 slightlyforked tail of moderatelength. It absolutely dwarfedevery swallowin association,even at great distances.It was substantially longerthan a Cliff Swallowseen in directcomparison. Gary Lesterfelt the wingspan wasdouble that of a Barn Swallow;I thoughtit was maybenot quitetwice as much. The plumage was entirelyblackish except for a conspicuouscomplete white collar, narrowestand cleanestacross the nape but broaderand lessdistinct and descending posteriorlysomewhat across .the breast. This collar, especially on the nape, wasvisible Western Birds 20:25-31, 1989 25