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dc.contributor.authorDivoky, George Joseph
dc.date.accessioned2018-08-08T19:03:21Z
dc.date.available2018-08-08T19:03:21Z
dc.date.issued1998
dc.identifier.urihttp://hdl.handle.net/11122/9472
dc.descriptionThesis (Ph.D.) University of Alaska Fairbanks, 1998
dc.description.abstractAnnual variation in breeding populations at seabird colonies has been well documented, but there have been few long-term attempts to examine the environmental and demographic forces responsible. I studied breeding chronology and demography Black Guillemot in northern Alaska from 1975-1997 to identify the factors responsible for colony establishment and growth. The Black Guillemot is a cavity-nesting seabird whose populations are frequently limited by nest-site availability. Snowmelt in spring and snow accumulation in autumn had major effects on annual nesting initiation and success, respectively. Annual arrival at the colony and median date of egg laying was well correlated with the date of snow disappearance, with annual clutch initiation advancing 4.5 days per decade in response to regional climate amelioration. Successful breeding requires a snowfree cavity for ${>}80$ days. Decreased breeding success and post-fledging survival occurred in a year with a snow-free period ${<}80$ days. Historic weather records indicate annual snowfree periods ${>}80$ days were uncommon until the 1960's, when the species was first recorded breeding in northern Alaska. When additional nest sites were provided, growth of the colony was rapid, increasing from 18 pairs in 1975 to 225 pairs in 1989. Breeding numbers then decreased to 150 in 1996 as factors other than nest-site availability controlled population size.
dc.subjectEcology
dc.subjectZoology
dc.titleFactors affecting the growth of a black guillemot colony in northern Alaska
dc.typeThesis
dc.type.degreephd
dc.identifier.departmentDepartment of Biology and Wildlife
refterms.dateFOA2020-03-06T01:19:27Z


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