Keywords
Phalacrocorax atriceps
breeding
Patagonia
Argentina
Abstract
We studied the breeding ecology of Imperial Shags (Phalacrocorax atriceps) in Deseada Island (Santa Cruz, Argentina), during the breeding season of 1994-95. The shags arrived to the island in early August, they rebuilt their nests and started to lay eggs during late October, with a peak of egg production in the first two weeks of November. The modal clutch size was three eggs. Hatching started in late November. The maximum mean brood size was observed in mid-December (1.4 chicks). Hatching success was 53%, whereas the survival of chicks was 60%. Neither hatching success nor chick survival differed among nests located in distinct sectors of the colony. In mid-February the juvenile (approximately 60 days of age): adult ratio was 1:3. AIl the juvenile shags left the island in late March, together with most adults.
References
ALBR/Eu,C.&J.L.NAVARRO.1997.Localizacióny ta-mañopoblacionaldecormOl'anerasenlaRíaDe-seado(SantaCruz,Argentina).Hornero14:243-246.
CROXALL,J.P.&P.ROTHERY.1994.Populationregula-tionofseabirds:implicationsoftheirdemographyforconservation.Pp:272-296,In:Birdpopulationstudies:relevancetoconservationandmanagement.Perrins,C.M.;J.D.Lebreton&G.J.M.Hirons(eds.).OxfordUniv.Press,NewYork.
DEVILLERS,P.&J.A.TERscHuREN.1978.RelationshipsbetweentheBlue-eyedShagsofSouthAmerica.LeGerfaut68:53-86.
GANDINI,P.&E.FRERE.1995.Distribución,abundan-ciay cicloreproductivodelCormoránGrisPhala-crocoraxgaimardienlacostapatagónica,Argen-tina.Hornero14:57-60.
KURY,C.&M.GOCHFELD.1975.Humaninterferenceandgullpredationincormorantcolonies.Biol.Conservo(8):23-34.
MALAcALzA,V.E.1984a.Avesguaneras.Relevamien-todetresespeciescontinentalesdelaprovinciadelChubut(Argentina).CentroNacionalPatagónico,ContribuciónNro.84.
MALACALZA,V.E.1984b.BiologíareproductivadePha·lacrocoraxalbiventer.NidificaciónenPuntaTom-bo.CentroNacionalPatagónico,ContribuciónNro.98.
MALACALZAV.E.&J.R.NAVAS.1996.Biologíay eco-logíareproductivadePhalacrocoraxalbivenler(Aves:Phalacrocoracidae)enPuntaLeón,Chubut,Argentina.OrnitologíaNeotropical7:53-61.
POTTS,G.R.;J.C.COULSON&I.R.DEANs.1980.Popu-lationdynamicsandbreedingsuccessoftheshag,Phalacrocoraxaristotelis,ontheFarneIslands,Northumberland.J.Anim.Ecol.49:465-484.
PUNTA,G.1989.GuanerasdelaprovinciadelChubut.Potencialidadproductivayfundamentosparasumanejoracional.Dir.Imp.Of.,Rawson,Argenti-na,113pp.
PUNTA,G.1996.Estadodesituacióndelrecursogua-neroenlaRepúblicaArgentina.InformesTécni-cosdelplandemanejointegradodelazonacoste-rapatagónica- FundaciónPatagoniaNatural(Puer-toMadryn,Argentina).N°6:1-57.
RASMUSSEN,P.C.1991.RelationshipsbetweencoastalSouthAmericanKingandBlue-Eyedshag.Con-dor93:825-839.
SUBSECRETARIADEESTADODEPLANEAMIENTO.1982.In-formeMunicipal.DirecciónGeneraldeAdminis-tracióndelDesarrollo,ProvinciadeSantaCruz.DiagnósticoProvincial:210-243.
YORIO,P.&F.QUINTANA.1996.EfectosdeldisturbiohumanosobreunacoloniamixtadeavesmarinasenPatagonia.Hornero14:60-66.
YORIO;P.&G.HARRIS.1997.Distribuciónreproducti-vadeavesmarinasy costerascolonialesenPata-gonia:relevamientoaéreoBahíaBlanca- CaboVír-genes,noviembre1990.InformesTécnicosdelplandemanejointegradodelazonacosterapatagónica- FundaciónPatagoniaNatural(PuertoMadryn,Argentina).N°29:1-31
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.