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Reference: Petersen, Ævar., (1981). Breeding biology and feeding ecology of Black guillemots. DPhil. University of Oxford.Citable link to this page:


Breeding biology and feeding ecology of Black guillemots

Abstract: Since 1974 a population study of Black Guillemots has beenconducted on Flatey Island, NW Iceland. The main aspectsare summarized below.Population numbers and distribution. The population hasbeen censused several years, also those of 20 islets near Flatey.Information was collected on past status. Great changes haveoccurred since turn of the century. Last major change began in1967; the population started increasing of such a scale thatit can only have resulted from massive immigration. Thesechanges are thought to be due to rats and Mink.Attendance and population structure. Data was gatheredon timing of spring return to nesting areas, status of attendingbirds, sex ratio, area and nest-site fidelity, pair-bondmaintenance, and post-breeding departure. Special attentionhas been given to the problem of censusing birds attendingnesting areas.Breeding biology. Breeding biology variables were quantifiedand studied on a seasonal basisj;timing of laying, clutchsize, interval between eggs, egg size, reproductive output,lengths of incubation and nestling periods. Supernormal clutchand brood experiments were conducted. I looked at length ofreplacement time of lost clutches, factors influencing timing oflaying, its effect and that of clutch and egg size on breedingperformance. Egg and chick losses were analyzed. Many interestingpopulation phenomena seem to have been associated with the unusuallyrapid population increase.Feeding ecology. Analyses were made of prey taken,feeding rhythm and areas, and factors influencing feedingrate and prey selection. Some information was collected onshare of the sexes in feeding chicks, and kleptoparasitism.Study was made of chick growth, fledging condition and postfledgingsurvival.Population dynamics. About 3300 birds were ringed,providing basis for determining age at maturity, adult survival,and mortality. Pre-breeding survival was calculatedusing data from ringing schemes. A population model wasconstructed for the population, showing magnitude of immigration.Ringing provided data on dispersal.

Type of Award:DPhil Level of Award:Doctoral Awarding Institution: University of Oxford Notes:This thesis was digitised thanks to the generosity of Dr Leonard PolonskyNotes:The copy of this thesis available for download has had copyrighted diagrams removed. For the full thesis please contact the ORA team.


Perrins, Christopher M.More by this contributor



Chris PerrinsMore by this contributor


 Bibliographic Details

Issue Date: 1981Identifiers

Urn: uuid:0588a5d4-b98e-482d-b70f-5e38dbc1f923

Source identifier: 602831573 Item Description

Type: Thesis;

Language: eng Subjects: Iceland Flatey Black guillemot Breeding Food Ecology Tiny URL: td:602831573


Autor: Petersen, Ævar. - institutionUniversity of Oxford facultyDept. of Zoology facultyLife and Environmental Sciences Division - - -



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