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      Comparative reproductive strategies between long-tailed ducks and king eiders at Karrak Lake, Nunavut: use of energy resources during the nesting season

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      Shona_Lawson_Thesis_2006_SEPT_1_.pdf (737.9Kb)
      Date
      2006-08-31
      Author
      Lawson, Shona Louise
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (Clangula hyemalis) and King Eider (Somateria spectabilis) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a “mixed” breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.
      Degree
      Master of Science (M.Sc.)
      Department
      Biology
      Program
      Biology
      Supervisor
      Alisauskas, Ray T.
      Copyright Date
      August 2006
      URI
      http://hdl.handle.net/10388/etd-09202006-233329
      Subject
      eggs
      nutrients
      exogenous
      endogenous
      carbon-13
      Long-tailed Duck
      Clangula hyemalis
      King Eider
      Somateria spectabilis
      stable isotopes
      d15N
      d13C
      nitrogen-15
      nest success
      population delineation
      incubation rhythms
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