sign in sign up
<<
Home , Clipperton Island

NORTH AMERICAN MIGRANT BIRDS ON CLIPPERTON

STEVE N. G. HOWELL, PETER PYLE. AND LARRY B. SPEAR. Point ReyesBird Observatory.4990 ShorelineHighway. Stinson Beach. California 92038 ROBERT L. PITMAN. National Marine Fisheries Service, Southwest Fisheries Center. P.O. Box 271, La Jolla, California 92038

ClippertonAtoll lies in the easternPacific about 1000 km south- westof Guerrero,, at 10 ø 18'N, 109 ø 13'W, and, likemany remote ,is visitedrarely by biologists.Although known mostlyas a major breedingground for seabirds,29 speciesof northernmigrant birds have been reportedfrom the (Beck 1907, Ehrhardt1971. Gifford 1913, Haeze et al. 1967, Howell 1959, Niaussatet al. 1968. Stager 1964). We visitedClipperton on sevenoccasions: 19 August 1986 (Pitman),6 May 1987 (Pitman).1 November1987 (Pyle and Spear). 24-25 October 1989 (Howell and Spear), 11 November1990 (Pitman),4 December1990 (Howell,Spear, and S. Webb),and 23 October 1991 (Spear).During these visitswe recordeda total of 80 speciesof North Americanmigrants, 57 of them previouslyunreported from the atoll. Here we summarizerecords of

Figure 1. ClippertonAtoll, 23 October 1991. A view acrossthe lagoonfrom the smallcoconut grove at the landingsite on the atoll'snortheast side: on the opposite shore note the large coconutgrove, a major concentrationpoint for vagrantland birds.

Photo by Larry B. Spear Western Birds 24:73-80, 1993 MIGRANT BIRDS ON CLIPPERTON ATOLL migrantbirds from Clipperton,with the exceptionof pelagicmigrants and breedingseabirds. Previously unreported species whose identification we considerproblematic are described. The atoll, approximately10.5 km in circumferenceand 50-300 m wide, surroundsa stagnantmurky lagoon up to 1.5 km in diameter.Most of the landis bare coralrubble except for a few coconutpalms (Cocos nucifera), the main grovesof which(Figure 1) act as magnetsfor migrantlandbirds. In addition,a few grassyislets in the lagoonand the muddybay at Clipperton Rock (seemap in Stager 1964) concentratewaterbirds. Except in 1991 (whenonly the northside of the atollwas visited briefly), we were ableto makeobservations at all of thesepoints, and walks around the entireisland confirmedthat very few migrantsoccurred away from them. We have considerableexperience with all speciesencountered, and identifications were oftenfacilitated by the birds'being tired and easilyapproached. Severalof the landbirdsin October and November,and all of those in December,were weak and sickly-looking;this, together with the paucityof landbirdsin December,suggests that many perishon the island.Some waterbirds,however, in particularherons and ducks, may be able to overwinteror at leastsurvive longer on Clipperton.Common Moorhens have successfullycolonized the atoll since 1968, but American Coots, reportedas breedingcommonly by Stager(1964), now occurin reduced numbersand may no longernest on Clipperton.Relatively few shorebirds were foundin December,suggesting that the majorityoccurring earlier in the autumnwere transientsor vagrants. The followingspecies accounts summarize the occurrenceof all North Americanmigrants recorded on ClippertonAtoll. The only other landbird known from Clipperton is the Dark-billed (Coccyzus melacoryphus),an australmigrant from SouthAmerica (Stager 1964). In the list, lack of referenceto other sourcesindicates a speciespreviously unreportedfrom Clipperton.

SPECIES ACCOUNTS

AmericanBittern, Botaurus lentiginosus. Nov 1987, 1. LeastBittern, Ixobrychus exilis. Aug 1958, 1 femalecollected (Stager 1964). GreatBlue Heron, Arclea heroclias. May 1987, 1; Nov 1987, 4; Nov 1990, 1. Great Egret, Casmerodiusalbus. Nov 1987, 1. SnowyEgret, Egretta thula. Nov 1987, 3. Cattle Egret,Bubulcus ibis. Aug 1986, 1; May 1987, 2; Nov 1987, 100; Oct 1989, 32; Nov 1990, 25; Dec 1990, 3. Alsoreported by Haezeet al. (1967) and Niaussatet al. (1968). Black-crownedNight-Heron, Nycticorax nycticorax. Nov 1987, 1 adult. Yellow-crownedNight-Heron, N. violaceus.Nov 1987, 1 immature;Nov 1990, 1 first-year;Dec 1990, 1 second-year. White-facedIbis, Plegaclis chihi. Oct 1989, 3; Dec1990, 1. Identifiedby reddish iridesand plain slaw gray lores (see Howell and de Montes1989). 74 MIGRANT BIRDS ON CLIPPERTON ATOLL

Plegadissp. Nov 1987.1: Nov 1990, 2. Alsoreported in Nov 1901 (Beck1907). WhiteIbis, Eudocimus albus. May 1987.1 adult(Figure 2); Nov 1987, 1 adult. Northern Pintail,Anas acura. Nov 1987.5; Nov 1990, 50; Dec 1990.50. Also Nov 1901 (Beck 1907). Blue-wingedTeal. A. discors.Nov 1987, 16- Nov 1990, 30; Dec 1990, 9. Also Nov 1901 (Beck 1907). CinnamonTeal, A. cyanoptera.Dec 1990.1. Carefullycompared with accompa- nying Blue-wingedTeal, identifiedby more spatularebill, overallwarm brown plumageincluding head and neck. plain face with whitish eye-crescents. Blue-winged/CinnamonTeal, A. discors/cyanoptera.Dec 1990.55. NorthernShoveler. A. clypeata.Nov 1990. 6; Dec 1990, 20. Also Nov 1901 (Beck 1907). EurasianWigeon, A. penelope. Dec 1990, 1. Among 140+ duckspresent, Howell and S. Webb founda femaleEurasian Wigeon. The bird associatedwith a male AmericanWigeon which it resembledin shapeand size.The head and neck weregrayish chestnut, without a darkeye patch. and did not contrast with the chest. In flightthe axillarswere seento be grayish. AmericanWigeon, A. americana.Dec 1990, 1 male. Alsoreported by Beck (1907). Canvasback,Aythya valisineria.Nov 1901, 1 seen(Beck 1907). Ring-neckedDuck, A. collaris.Dec 1990, 2 females.

Figure2. AdultWhite Ibisat Clipperton,6 May 1987. Photo by Robert L. Pitman

75 MIGRANT BIRDS ON CLIPPERTON ATOLL

LesserScaup, A. affinis. Dec 1990, 2 males,2 females. Unidentifiedscaup, Aythya affinis/marila. Nov 1990, 5. Osprey, Pandion haliaetus. Nov 1987, 1; Oct 1989, 1; Dec 1990, 1. Also reportedby Stager(1964). PeregrineFalcon, Falco peregrinus. Nov 1987, 1 adult;Dec 1990, 1 juvenile. VirginiaRail, Rallus limicola. Nov ,:1987,1. Sora, Porzana carolina. Nov 1987, 1; Oct 1989, 1; Dec 1990, 1. PurpleGallinule, Porphyrula martinica. Oct 1989, 1 immature.Also reported by Haeze et al. (1967). Common Moorhen, Gallinula chloropus.Aug 1986, 4; May 1987, 30; Nov 1987, 35 includingchicks; Oct 1989, 15 includingone smallchick; Nov 1990, 20; Dec 1990, 40 including5 or 6 small chicks.A recent and apparentlysuccessful colonist. American Coot, Fulica americana. Nov 1987, 3. Nov 1990, 10; Dec 1990, 2. Uncommon and apparently irregular in recent years, but bred commonly at Clippertonfrom at least1958 to 1968 (Stager1964, Ehrhardt1971). Black-belliedPlover, Pluvialis squatarola. Aug 1986, 1; Nov 1987, 1; Nov 1990, 1. Also Nov 1901 (Beck 1907). PacificGolden Plover, P. fulva. Nov 1987, 1. AlsoAug 1958, 1 collected(Stager 1964). Unidentifiedgolden plover, P. /fulva. May 1987, 1; Oct 1989, 1. SemipalmatedPlover, Charadrius semipalmatus.Nov 1987, 8; Oct 1989, 4; Nov 1990, 6; Dec 1990, 12. Killdeer,C. vociferus.Nov 1987, 1; Nov 1990, 1; Dec 1990, 3. Greater Yellowlegs,Tringa melanoleuca. Nov 1987, 1; Oct 1989, 1. Also reportedby Ehrhardt(1971). LesserYellowlegs, T. flavipes. Nov 1987, 1; Oct 1989, 1. Also reported by Ehrhardt (1971). SolitarySandpiper, T. solitaria. Nov 1987, 1; Oct 1989, 1. WanderingTattler, Heteroscelus incanus. Aug 1986, 30; May 1987, 29; Nov 1987, 100; Oct 1989, 24, Nov 1990, 25; Dec 1990, 1. Alsoreported by Gifford (1913) and Stager(1964). SpottedSandpiper, Actitis macularia.Nov 1987, 1. AlsoAug 1958, 1 collected (Stager1964). Whimbrel,Nurnenius phaeopus hudsonicus. May 1987, 2; Nov 1987, 4. Also Nov 1901 (Beck 1907). RuddyTurnstone, ArenariG interpres.Aug 1986, 1; Nov 1987, 17; Nov 1990, 1. AlsoAug 1958, 7 (Stager1964). Sanderling,Calidris alba. Nov 1987, 2; Oct 1989, 6. WesternSandpiper, C. mauri. Nov 1990, 1; Dec 1990, 1. Least Sandpiper,C. minutilla. Nov 1990, 3; Dec 1990, 4. PectoralSandpiper, C. melanotos.Nov 1987, 2; Oct 1991, 2. Long-billedDowitcher, Limnodromus scolopaceus. Nov 1990, 3.

76 MIGRANT BIRDS ON CLIPPERTON ATOLL

Wilson'sPhalarope, Phalaropus tricolor. Aug 1958, 1 collected(Stager 1964). Red Phalarope,P. fulicaria. Dec 1990, 2. LaughingGull, Larus atticilia. May 1987, 23• Oct 1989, 4; Nov 1989, 4; Dec 1990, 2. Franklin'sGull, L. pipixcan. Nov 1987, 1. Common Tern. Sterna hitundo. Nov 1987. 1. Tern, $. paradisaea. Nov 1987, 50. Black Tern, Chlidonias niger. Nov 1987, 1 corpsefound. Also Aug 1958, 1 collected(Stager 1964). MourningDove, Zenaida macroura.May 1987, 2. Yellow-billedCuckoo, Coccyzusamericanus. Reported by Niaussatet al. (1968). Common Nighthawk,Choralelies minor. May 1987, 1 female. Observedand photographedat closerange, roosting on the coralrubble and in flight(Figure 3). BeltedKingfisher, Ceryle alcyon. Nov 1987, 2; Oct 1989, 1; Nov 1990, 1; Dec 1990, 1. EasternWood-Pewee, Contopus virens. Nov 1987, 1. Identifiedby olive-green upperparts;mostly pale underparts(including the medianchest) with diffusedusky streakingon the chestsides; bright, whitish to lemonwingbars and secondaryedges; brightorange basal 4/5 (includingthe sides)of the lowermandible; and the song,a

Figure3. FemaleCommon Nighthawk at Clipperton,6 May 1987. In springthe combinationof a whitewing band and the lackof a whitetail bar rulesout the Lesser Nighthawk(Chordeiles acutipennis); note also the positionof the whitewing band. Photo by Robert L. Pitman

77 MIGRANT BIRDS ON CLIPPERTON ATOLL

full,clear peeew-weee of 1-2 secondsduration. From extensiveexperience with both wood-peweesand the problemsof theirseparation, Pyle considered the plumageand songoutside the rangeof WesternWood-Pewee variation. Unidentifiedpewee, C. virens/sordidulus.Oct 1989, 1. Empidonaxsp. Nov 1987, 1, probablya Yellow-belliedFlycatcher, E. flavi ventris. PurpleMartin, Progne subis. Aug 1986, 15; Nov 1987, 1. AlsoAug 1958 (Stager 1964) and 1968 (Ehrhardt1971). Progne sp. Nov 1987, 2; Oct 1989, 1. Thesebirds were not PurpleMartins and probablywere Gray-breastedMartins, P. chalybea. Tree Swallow, Tachy½inetabi½olor. Dec 1990, 2. Bank Swallow,Riparia riparia. Nov 1987, 1; Oct 1989, 3. Cliff Swallow,Hitundo pyrrhonota. Aug 1986, 1. Barn Swallow,Hitundo rustlea. Nov 1987, 100; Oct 1989, 2; Nov 1990, 2; Dec 1990, 3; Oct 1991, 100. Troglodytessp. Nov 1987, 1, probablya HouseWren, T. aedon. Gray-cheekedThrush, Catharus minimus. Oct 1989, 2 or 3. These birdswere tired and couldbe observedat closerange. Identified by the gray-brownhead and upperparts,including upper tail, the inconspicuousnarrow whitisheyering that widenedslightly behind the eye, and the whitishthroat and underpartswashed pale buff on the chestand spotteddark brown on the chestand sidesof throat. AmericanPipit, Anthus rubescens.Nov 1987, 1. Golden-wingedWarble•, Vermivora ½hrysoptera. Nov 1987, 1 male. TennesseeWarbler, V. peregrina. Nov 1987, 2. Also Oct 1956, 1 collected (Howell 1959). YellowWarbler, Dendroica petechia. Nov 1987, 1. AlsoAug 1958, 1 collected (Stager1964). MagnoliaWarbler, D. magnolia.Nov 1987, 1; Oct 1989, 1. Black-throatedGreen Warbler,D. virens.Oct 1991, 1. Yellow-throatedWarbler, D. dominicaalbilora. Aug 1958, 1 collected(Stager 1964). PrairieWarbler, D. discolor.Nov 1987, 1. PalmWarbler, D. palmarum. Nov 1987, 2. Bay-breastedWarbler, D. ½astanea.Oct 1956, 1 collected(Howell 1959). BlackpollWarbler, D. striata. Oct 1989, 1; Nov 1990, 1; Oct 1991, 1. AmericanRedstart, Setophaga ruticilla. May 1987, 1; Nov 1987, 3; Oct 1989, 1. AlsoAug 1958 (Stager1964). ProthonotaryWarbler, Protonotaria ½itrea. Nov 1987, 1; Oct 1989, 2; Nov 1990, 1. Ovenbird,Seiurus aurocapillus. Nov 1987, 2; Oct 1989, 1. Northern Waterthrush,S. noveboracensis.Nov 1987, 3; Nov 1990, 1; Oct 1991, 1. ConnecticutWarbler, Oporornis agilis. Nov 1987, 1, probablyan immature female.Studied walking under some shrubbery in themain grove. A largeOporornis MIGRANT BIRDS ON CLIPPERTON ATOLL warbler. uniformly dull olive on the back and rather bright yellow on the lower underparts.The throat and breastwere bully brown. A full bully-whiteeyering was present The legswere bright pink. These characters plus the persistentwalking habit are diagnosticof Connecticutamong the Oporornis warblers(Pyle and Henderson 1990). Common Yellowthroat,Geothlypis trichas. Nov 1987, 1. Warbler, IA/ilsoniacanadensis. Nov 1987, 1. SummerTanager, Piranga rubra. Nov 1987, 3; Oct 1989, 1. Also Oct 1956, 1 collected (Howell 1959). ScarletTanager. Piranga olivacea. Oct 1991, 1 immaturemale (Figure4). Piranga sp. Nov 1990, 1, probablya SummerTanager. Bobolink, Dolichonyx oryzivorus. Nov 1987, 3: Oct 1989, 6: Dec 1990, 2. Icterus sp. Nov 1987, 1, probablya Northern Oriole, I. galbula.

Figure4. Immaturemale ScarletTanager at Clipperton, 23 October 1991. Photo by Larry B. Spear

79 MIGRANT BIRDS ON CLIPPERTON ATOLL

ACKNOWLEDGMENTS

Researchconducted by Point ReyesBird Observatory(PRBO) on seabirdecology at , coordinatedby DavidAinley and ChrisRibic, enabled access to Clippertonby Howell, Pyle,and Spear.National Geographic Society grants 3321-86 and 4106-89 and National ScienceFoundation grants OCE 8515637 and OCE 8911125 sup- ported the researchcruises in which PRBO personnelparticipated. Pitman's visits coincidedwith studiesby the NationalMarine Fisheries Service, during which field supportwas providedby J. and G. Friedrichsen,R. Rowlett,J. Cotton, J. Carretta, and J. Gilardi.Our visitsto Clippertonwere arrangedand made possibleby the National Oceanographicand AtmosphericAdministration (NOAA), and we thank the officersand crew of the NOAA shipsDiscoverer, Oceanographer, Malcolm Baldridge, David Starr Jordan, and l•lcArthur for logisticalsupport. We thank David Ainley and Roger B. Clapp for helpful commentsthe manuscript.This is contribution530 of Point ReyesBird Observatory.

LITERATURE CITED

Beck, R. H. 1907. Notes from Clippertonand Cocosislands. Condor 9:109-110. Ehrhardt,J.P. 1971. Censusof the birdsof ClippertonIsland, 1968. Condor 73: 476-480. Gifford, E. W. 1913. Expeditionof the California Academy of Sciencesto the GalapagosIslands, 1905-1906. VIII. The birdsof the GalapagosIslands with observationson the birdsof Cocosand Clippertonislands. (Columbiformes to Pelecaniformes).Proc. Calif. Acad. Sci., 4th ser., 2:1-132. Haeze, G., Wissocq,J. C., Barloy,J., and Niaussat,P. 1967. Etudezoologique des esp•ces rapport,es' de la Mission Bougainville, Groupe Rouge. Rapport particulier du Centre de Recherches du Service de Sant• des Armies (C.R.S.S.A.),Division de BiologieG•n•rale et Ecologie(Biol. Ecol.)25:16-18. Howell, S. N. G., and de Montes, B. M. 1989. Statusof the GlossyIbis in Mexico. Am. Birds 43:43-45. Howell, T. R. 1959. Land birdsfrom ClippertonIsland. Condor 61:155-156. Niaussat,P., Barloy,J., and Haeze, G. 1963. Contributiona l'•tude des oiseauxde ratoll de Clipperton.Rapport particulier, C.R.S.S.A., Biol. Ecol. 32:1-17. Pyle, P., and Henderson,P. 1990. On separatingfemale and immatureOporornis warblersin fall. Birding22:222-229. Stager,K. E. 1964. The birdsof ClippertonIsland, Eastern Pacific. Condor 66:357- 371.

Accepted 24 July 1992

$0