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dc.contributor.authorJohnson, Devin Leland
dc.date.accessioned2021-12-17T17:46:09Z
dc.date.available2021-12-17T17:46:09Z
dc.date.issued2021-08
dc.identifier.urihttp://hdl.handle.net/11122/12622
dc.descriptionDissertation (Ph.D.) University of Alaska Fairbanks, 2021en_US
dc.description.abstractAs top predators in a rapidly changing environment, Arctic raptors serve as indicator species of ecosystem health. The degree to which populations exhibit dietary plasticity and partition resources on an interspecific basis under dynamic ecological conditions may be indicative of climate change resilience. It is therefore crucial to develop accurate and broadly applicable methods for characterizing the diets of wild populations. In this dissertation, I assessed the performance of Bayesian stable isotope mixing models (BSIMMs) as a method of characterizing diet in free-living raptor populations, developed novel methods to refine their accuracy and applicability, and applied an isotopic approach to address broad trophic hypotheses within an Arctic raptor guild. First, I evaluated the use of BSIMMs in a population of Gyrfalcons (Falco rusticolus) by comparing modelled diet estimates to high-accuracy nest camera diet data. I found that the isotopic method effectively characterized diet at the population level and accurately identified temporal shifts in Gyrfalcon diet on a seasonal and interannual basis. Second, I developed a novel method for the estimation of trophic discrimination factors (TDFs) in wild populations and tested it in three published datasets. The new method outperformed other methods of TDF estimation in all cases, ultimately increasing the accuracy and applicability of the BSIMM approach under certain circumstances. Third, I applied an isotopic approach to characterize interspecific niche overlap and individual specialization in an Arctic raptor guild (Gyrfalcons, Golden Eagles [Aquila chrysaetos], and Rough-legged Hawks [Buteo lagopus]) under varying degrees of resource abundance. I found the three species overlap in their isotopic niche, but that overlap was reduced when more prey types were available (i.e., an influx of cyclic arvicoline rodents). In Gyrfalcons, the level of individual specialization increased with increasing population niche width in accordance with the niche variation hypothesis.en_US
dc.description.sponsorshipPeregrine Fund's Gyrfalcon & Tundra Conservation Program, Alaska Department of Fish and Game's State Wildlife Grant Program, Calvin J Lensink Fund, Angus Gavin Migratory Bird Research Granten_US
dc.description.tableofcontentsChapter 1: Introduction -- Chapter 2: Bayesian stable isotope mixing models effectively characterize the diet of an Arctic raptor -- Chapter 3: TDFCAM: a novel method for estimating trophic discrimination in wild populations -- Chapter 5: Conclusion -- Appendices.en_US
dc.language.isoen_USen_US
dc.subjectBirds of preyen_US
dc.subjectGyrfalconen_US
dc.subjectStable isotopes in ecological researchen_US
dc.subjectFood chainsen_US
dc.subjectEcologyen_US
dc.subject.otherDoctor of Philosophy in Biological Sciencesen_US
dc.titleStable isotope ecology of an Arctic raptor guilden_US
dc.typeDissertationen_US
dc.type.degreephden_US
dc.identifier.departmentWildlife Biology and Conservation Programen_US
dc.contributor.chairWilliams, Cory
dc.contributor.committeeAnderson, David
dc.contributor.committeeBooms, Travis
dc.contributor.committeeBreed, Greg
dc.contributor.committeeO'Brien, Diane
refterms.dateFOA2021-12-17T17:46:09Z


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