Reproductive tactics under severe egg predation: an eider’s dilemma

Andersson, Malte; Waldeck, Peter

doi:10.1007/s00442-006-0374-7

Cited by 35 publications

(27 citation statements)

References 38 publications

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“…The experiment closely mimicked eider nests after the Wrst egg has been laid: females leave this egg unattended in the nest, carefully covering it with substrate other than down, and then return to sea to feed. Permanent presence at the nest starts from the second or third egg (Swennen et al 1993;Robertson 1998;Hanssen et al 2002;Andersson and Waldeck 2006). The second egg is laid about 1.2 days after the Wrst (Andersson and Waldeck 2006).…”

Section: Field Experiments 1: Egg Predationmentioning

confidence: 99%

“…However, an alternative explanation is available: females leave their Wrst one or two egg(s) unattended in the nest and accessible to predators, so a later count of clutch size will underestimate the actual number of eggs laid by a female, as females do not compensate for eggs lost during laying (Swennen et al 1993;Erikstad and Bustnes 1994). This is especially true in exposed nests, where partial egg predation is high (Milne 1974; Götmark and Åhlund 1988;Laurila 1989;Andersson and Waldeck 2006). Partial predation on Wrst-laid eggs is diYcult to detect, as the most common egg predators, corvids, typically transport the eggs away from the nest (Milne 1974;Loman and Göransson 1978;Gerell 1985).…”

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confidence: 93%

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Habitat-specific clutch size and cost of incubation in eiders reconsidered

Öst¹,

Wickman

Matulionis³

et al. 2008

Oecologia

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The energetic incubation constraint hypothesis (EICH) for clutch size states that birds breeding in poor habitat may free up resources for future reproduction by laying a smaller clutch. The eider (Somateria mollissima) is considered a candidate for supporting this hypothesis. Clutch size is smaller in exposed nests, presumably because of faster heat loss and higher incubation cost, and, hence, smaller optimal clutch size. However, an alternative explanation is partial predation: the first egg(s) are left unattended and vulnerable to predation, which may disproportionately affect exposed nests, so clutch size may be underestimated. We experimentally investigated whether predation on first-laid eggs in eiders depends on nest cover. We then re-evaluated how nesting habitat affects clutch size and incubation costs based on long-term data, accounting for confounding effects between habitat and individual quality. We also experimentally assessed adult survival costs of nesting in sheltered nests. The risk of egg predation in experimental nests decreased with cover. Confounding between individual and habitat quality is unlikely, as clutch size was also smaller in open nests within individuals, and early and late breeders had similar nest cover characteristics. A trade-off between clutch and female safety may explain nest cover variation, as the risk of female capture by us, mimicking predation on adults, increased with nest cover. Nest habitat had no effect on female hatching weight or weight loss, while lower temperature during incubation had an unanticipated positive relationship with hatching weight. There were no indications of elevated costs of incubating larger clutches, while clutch size and colony size were positively correlated, a pattern not predicted by the 'energetic incubation constraint' hypothesis. Differential partial clutch predation thus offers the more parsimonious explanation for clutch size variation among habitats in eiders, highlighting the need for caution when analysing fecundity and associated life-history parameters when habitat-specific rates of clutch predation occur.

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Section: Field Experiments 1: Egg Predationmentioning

confidence: 99%

mentioning

confidence: 93%

Habitat-specific clutch size and cost of incubation in eiders reconsidered

Öst¹,

Wickman

Matulionis³

et al. 2008

Oecologia

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“…On average, 19 examined females from Svalbard had more than twice as many ruptured follicles (6.2) as the number of eggs in their nest (2.6), probably because of early egg predation (Ahlén and Andersson 1970), which is high in arctic-breeding common eiders (e.g., Mehlum 1991a, b;Robertson and Cooke 1993;Andersson and Waldeck 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Here, we study arctic common eiders S. mollissima borealis breeding in Svalbard, with high natural predation risk for the Wrst egg in the clutch, before the female sits permanently at the nest (Mehlum 1991b;Robertson and Cooke 1993;Swennen et al 1993;Hanssen et al 2002;Andersson and Waldeck 2006;Öst et al 2008). After predation of their Wrst eggs, some females did not desert the nest but continued laying in it.…”

Section: Introductionmentioning

confidence: 98%

Indeterminate laying and flexible clutch size in a capital breeder, the common eider

2010

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Clutch size control in capital breeders such as large waterfowl has been much debated. Some studies have concluded that clutch size in ducks is determined before the start of laying and does not change in response to egg additions or removals. The response, however, may depend on the timing of tests, and experiments may have been too late for females to alter the number of eggs. We here study clutch size responses to predation of first and second eggs in the common eider, using protein fingerprinting of egg albumen to verify that the same female continues laying in the nest after predation. Sixty of 79 females with early egg predation (one or both of the two first eggs) deserted the nest. Among the 19 females that stayed and continued laying, the mean number of eggs produced was 4.4, significantly higher than the 3.7 in non-predated nests. The staying females had similar egg size and clutch initiation date as females that deserted, and their body mass and clutch initiation date was similar to that of females whose clutches were not predated. Even capital-breeding common eiders may therefore be indeterminate layers, as many females in which early eggs are removed lay more eggs than others. A previous study has shown that they can reduce their laying if eggs are added. Our results add to increasing evidence that ducks have more flexible egg production than previously thought.

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“…Frequently, the number of post-ovulatory follicles was higher than the number of eggs found in nests (33 cases out of 52). In those cases, we assumed that missing eggs were the Wrst ones, given the low nest attendance of females at the beginning of laying and the high predation rate of Wrst eggs (Andersson and Waldeck 2006). In only two cases, the number of eggs found in the nest was higher than the number of post-ovulatory follicles, which indicated nest parasitism.…”

Section: Females and Eggs Collectionmentioning

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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Reproductive tactics under severe egg predation: an eider’s dilemma

Cited by 35 publications

References 38 publications

Habitat-specific clutch size and cost of incubation in eiders reconsidered

Habitat-specific clutch size and cost of incubation in eiders reconsidered

Indeterminate laying and flexible clutch size in a capital breeder, the common eider

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

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