Isotopic Evidence for Sources of Nutrients Allocated to Clutch Formation by Harlequin Ducks

Bond, Jeanine C.; Esler, Daniel; Hobson, Keith A.

doi:10.1650/8241.1

Cited by 28 publications

(25 citation statements)

References 35 publications

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“…Thus, while brent geese invest their body reserves into eggs and therefore have to forage extensively during incubation, king eiders may use exogenous resources for egg formation in order to retain body reserves for incubation (Bond et al 2007;Gorman et al 2008). As a consequence, there is potential for both endogenous and exogenous nutrient sources to be limiting to king eider reproduction.…”

Section: Do Eiders Retain Body Reserves For Incubation?mentioning

confidence: 99%

“…Where along that continuum a species falls depends on the general life history of the species as well as on the resource availability at the place and time of reproduction (Bonnet et al 1998;Houston et al 2007;Jönsson 1997). Many recent studies have used stable isotope applications to trace the origin of nutrients used for reproduction, in insects (O'Brien et al 2000(O'Brien et al , 2005, fish (Jardine et al 2008), reptiles (Warner et al 2008), mammals (Dalerum et al 2007), and especially in migratory birds (Bond et al 2007; Morrison and Hobson 2004;Schmutz et al 2006). The techniques used to quantify the allocation of nutrients via isotopic mixing models have advanced rapidly in the recent past (Moore and Semmens 2008;Parnell 2008;Phillips et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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King eiders use an income strategy for egg production: a case study for incorporating individual dietary variation into nutrient allocation research

2010

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The use of stored nutrients for reproduction represents an important component of life-history variation. Recent studies from several species have used stable isotopes to estimate the reliance on stored body reserves in reproduction. Such approaches rely on population-level dietary endpoints to characterize stored reserves ("capital") and current diet ("income"). Individual variation in diet choice has so far not been incorporated in such approaches, but is crucial for assessing variation in nutrient allocation strategies. We investigated nutrient allocation to egg production in a large-bodied sea duck in northern Alaska, the king eider (Somateria spectabilis). We first used Bayesian isotopic mixing models to quantify at the population level the amount of endogenous carbon and nitrogen invested into egg proteins based on carbon and nitrogen isotope ratios. We then defined the isotopic signature of the current diet of every nesting female based on isotope ratios of eggshell membranes, because diets varied isotopically among individual king eiders on breeding grounds. We used these individual-based dietary isotope signals to characterize nutrient allocation for each female in the study population. At the population level, the Bayesian and the individual-based approaches yielded identical results, and showed that king eiders used an income strategy for the synthesis of egg proteins. The majority of the carbon and nitrogen in albumen (C: 86 +/- 18%, N: 99 +/- 1%) and the nitrogen in lipid-free yolk (90 +/- 15%) were derived from food consumed on breeding grounds. Carbon in lipid-free yolk derived evenly from endogenous sources and current diet (exogenous C: 54 +/- 24%), but source contribution was highly variable among individual females. These results suggest that even large-bodied birds traditionally viewed as capital breeders use exogenous nutrients for reproduction. We recommend that investigations of nutrient allocation should incorporate individual variation into mixing models to reveal intraspecific variation in reproductive strategies.

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Section: Do Eiders Retain Body Reserves For Incubation?mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

King eiders use an income strategy for egg production: a case study for incorporating individual dietary variation into nutrient allocation research

2010

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“…Reproductive problems and low productivity have been documented for both species (Grand et al, 2002;Rojek, 2008). In Steller's and spectacled eiders, the relative importance of marine and terrestrial nutrients for reproduction is unknown, but there is evidence to suggest that some sea duck species acquire nutrients for successful breeding from both the terrestrial nesting and marine staging grounds (Bond et al, 2007;Sénéchal et al, 2011). A better understanding of diet sources and timing of nutrient acquisition for these eiders will provide information to help identify important pre-breeding habitats of threatened eider populations in Alaska.…”

Section: Introductionmentioning

confidence: 99%

Carbon isotopic fractionation in eider adipose tissue varies with fatty acid structure: implications for trophic studies

Budge

Wang

Hollmén

et al. 2011

Journal of Experimental Biology

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SUMMARYCarbon isotopic fractionation was investigated in fatty acids (FA) of adipose tissue and blood serum of threatened Stellerʼs eiders (Polysticta stelleri) and spectacled eiders (Somateria fischeri) relative to the FA in their diets. Captive eiders were fed a known diet for 180 days with serum sampled at 60, 120 and 180 days immediately after a 12 h fast; adipose was collected at 180 days. Essential FA (EFA) in the adipose showed varying degrees of isotope fractionation (0-4‰), depending on FA structure. The d13 C values of long-chain FA 20:5n-3 and 22:6n-3 did not differ from those in the diet, while those of 18:2n-6 and 18:3n-3 were ~2‰ greater than in the diet. The d13 C values of free FA (FFA) in serum were not consistent within individuals or sampling dates; fractionation varied randomly, suggesting that FFA were arising from diet, rather than mobilization from adipose tissue. Discrimination factors were used in combination with a mixing model incorporating FA and lipid concentrations to estimate the diet of eiders fed a binary mixture with contrasting isotopic signatures. Diet estimates varied with FA but mean values closely approximated the actual proportions consumed. By tracking EFA, this study avoided the complications in interpretation arising from isotopic routing of carbon in bulk isotope analyses and serves as a basis for the development of compound-specific isotopic methods to trace dietary input in wild eiders. However, our understanding of the processes contributing to the variation in isotopic signatures of FA in nature is currently limited, and we recommend that future research directions focus on elucidating these mechanisms.Key words: diet estimate, discrimination, lipid, compound-specific isotope analysis, stable isotope, Steller's eider, spectacled eider. THE JOURNAL OF EXPERIMENTAL BIOLOGY 3791Carbon isotopes of fatty acids in eiders of higher predators (e.g. Thiemann et al., 2007;Williams et al., 2008;Cooper et al., 2009), including captive eiders . FA are the primary components of most lipids and have a variety of structures. Because of biochemical restrictions, many dietary polyunsaturated FA (PUFA) are incorporated into marine animals with little modification to structure, making these FA valuable as indicators, or biomarkers, of their source. However, these biomarker techniques can only offer general information on temporal and spatial variation in consumer diets; much more complex models (i.e. quantitative fatty acid signature analysis, QFASA) (Iverson et al., 2004) are necessary to estimate proportions and types of prey species in predator diets using FA.Recently, we demonstrated the use of stable carbon isotopes of individual FA to trace carbon flow from prey to predator across multiple trophic levels in the Arctic (Budge et al., 2008 (Focken, 2004;Codron et al., 2011) and environmental factors (Bloomfield et al., 2011), and techniques such as lipid removal before isotopic analysis attempt to minimize its impact; however, it remains a complication in the interpretation of bul...

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“…We thus reject the hypothesis that common eiders are pure capital laying birds (Parker and Holm 1990;Meijer and Drent 1999). Like other well-studied bird species (e.g., Gauthier et al 2003;Hobson et al 2004Hobson et al , 2005Bond et al 2007;Gorman et al 2008), and several other organisms (Casas et al 2005;Stephens et al 2009), eiders in this population use a mixed capital-income breeding strategy. Relying exclusively on stored resources is likely non-adaptive in arctic-nesting eiders.…”

Section: Discussionmentioning

confidence: 50%

“…Given that mixed strategies are diYcult to quantify, it is especially challenging to compare animals studied using diVerent methods. Based on detailed stable isotope studies, Greater snow geese (Chen caerulescens atlantica; Gauthier et al 2003) and Barrow's goldeneye (Bucephala islandica; Hobson et al 2005) are the waterfowl species closest to the capital end of the capital-income continuum, while redhead (Aythya americana; Hobson et al 2004) and harlequin ducks (Histrionicus histrionicus; Bond et al 2007) were found to be mostly income layers. Considering egg formation and incubation strategies of arctic-nesting common eiders (which fast during the entire incubation; Bottitta et al 2003), it appears that they remain the most extreme known capital breeders among studied Xying birds.…”

Section: Discussionmentioning

confidence: 99%

Do purely capital layers exist among flying birds? Evidence of exogenous contribution to arctic-nesting common eider eggs

et al. 2010

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The strategy of relying extensively on stored resources for reproduction has been termed capital breeding and is in contrast to income breeding, where needs of reproduction are satisfied by exogenous (dietary) resources. Most species likely fall somewhere between these two extremes, and the position of an organism along this gradient can influence several key life-history traits. Common eiders (Somateria mollissima) are the only flying birds that are still typically considered pure capital breeders, suggesting that they depend exclusively on endogenous reserves to form their eggs and incubate. We investigated the annual and seasonal variation in contributions of endogenous and exogenous resources to egg formation in eiders breeding at the East Bay colony in the Canadian Arctic. We collected prey items along with females and their eggs during various stages of breeding and used two complementary analytical approaches: body reserve dynamics and stable isotope [δ(13)C, δ(15)N] mixing models. Indices of protein reserves remained stable from pre-laying to post-laying stages, while lipid reserves declined significantly during laying. Similarly, stable isotope analyses indicated that (1) exogenous nutrients derived from marine invertebrates strongly contributed to the formation of lipid-free egg constituents, and (2) yolk lipids were constituted mostly from endogenous lipids. We also found evidence of seasonal variation in the use of body reserves, with early breeders using proportionally more exogenous proteins to form each egg than late breeders. Based on these results, we reject the hypothesis that eiders are pure capital layers. In these flying birds, the fitness costs of a strict capital breeding strategy, such as temporary loss of flight capability and limitation of clutch and egg size, may outweigh benefits such as a reduction in egg predation rate.

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Isotopic Evidence for Sources of Nutrients Allocated to Clutch Formation by Harlequin Ducks

Cited by 28 publications

References 35 publications

King eiders use an income strategy for egg production: a case study for incorporating individual dietary variation into nutrient allocation research

King eiders use an income strategy for egg production: a case study for incorporating individual dietary variation into nutrient allocation research

Carbon isotopic fractionation in eider adipose tissue varies with fatty acid structure: implications for trophic studies

Do purely capital layers exist among flying birds? Evidence of exogenous contribution to arctic-nesting common eider eggs

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