Nesting Biology of the White-Winged Scoter

Brown, Patricia; Brown, Mary

doi:10.2307/3807871

Cited by 34 publications

(39 citation statements)

References 13 publications

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“…For example, we do not know if the nesting and molting scoter populations we sampled are the same population. To our knowledge, only one detailed nesting study of scoters has been conducted in North America (55). Nesting is generally considered one of the weakest links in the life cycle, especially with regard to contaminant effects.…”

Section: Interpretation Ofmetals Concentrationsmentioning

confidence: 99%

Contaminants and sea ducks in Alaska and the circumpolar region.

Henny¹,

Rudis²,

Roffe³

et al. 1995

Environ Health Perspect

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We review nesting sea duck population declines in Alaska during recent decades and explore the possibility that contaminants may be implicated. Aerial surveys of the surf scoter (Melanitta perspicillata), white-winged scoter (M. fusca), black scoter (M. nigra), oldsqaw (Clangula hyemalis), spectacled eider (Somateria fischeri), and Steller's eider (Polysticta stellei) show long-term breeding population declines, especially the latter three species. The spectacled eider was recently classified threatened under the Endangered Species Act. In addition, three other diving ducks, which commonly winter in coastal areas, have declined from unknown causes. Large die-offs of all three species of scoters during molt, a period of high energy demand, were documented in August 1990, 1991, and 1992 at coastal reefs in southeastern Alaska. There was no evidence of infectious diseases in those scoters. The die-offs may or may not be associated with the long-term declines. Many scoters had elevated renal concentrations of cadmium (high of 375 micrograms/g dry weight [dw]). Effects of cadmium in sea ducks are not well understood. Selenium concentrations in livers of nesting white-winged scoters were high; however, the eggs they laid contained less selenium than expected based on relationships for freshwater bird species. Histological evaluation found a high prevalence of hepatocellular vacuolation (49%), a degenerative change frequently associated with sublethal toxic insult. Cadmium and selenium mean liver concentrations were generally higher in those birds with more severe vacuolation; however, relationships were not statistically significant. We do not know if sea duck population declines are related to metals or other contaminants.

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Section: Interpretation Ofmetals Concentrationsmentioning

confidence: 99%

Contaminants and sea ducks in Alaska and the circumpolar region.

Henny¹,

Rudis²,

Roffe³

et al. 1995

Environ Health Perspect

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“…The mechanism for this pattern may be the relative timing of arrival and nest initiation in this species. Scoters arrive at their southern breeding grounds in late April to early May (Brown and Brown 1981), yet they arrive at our northern study site approximately one month later. At both sites, scoters nest, on average, in mid-June Fredrickson 1997, Traylor et al 2004, S. M. Slattery unpubl.…”

Section: Discussionmentioning

confidence: 99%

Combining Stable-Isotope and Body-Composition Analyses to Assess Nutrient-Allocation Strategies in Breeding White-Winged Scoters (Melanitta fusca)

DeVink

Slattery

Clark

et al. 2011

The Auk

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Birds meet the energy and nutrient demands of egg formation by using dietary (exogenous) sources, somatic (endogenous) nutrients, or combinations of both. Therefore, understanding plasticity in resource acquisition and the allocation strategies that are used is important for predicting how ecosystem changes across a species' range could affect vital rates. Sources of egg nutrients have traditionally been assessed through analyses of body composition, but stable-isotope analysis has provided a new tool in cases where animal tissues differ isotopically from the local food webs where they breed. We provide the first simultaneous comparison of these two techniques and test the "seasonally variable nutrient threshold hypothesis." Using body-composition analysis of Whitewinged Scoters {Melanitta fusca) collected at the northern extent of their range, we inferred that protein in rapidly developing ovarian follicles was derived entirely from dietary sources but that follicle lipids were most likely derived largely from somatic reserves. Stableisotope analysis confirmed that most protein was derived from dietary sources during early (70.7-86.6%) and late (83.4-94.4%) spring collection periods, but dietary lipids were not distinguishable isotopically from stored somatic lipids to estimate lipid contributions to eggs. This pattern dififered from that at the southern limit of the species' breeding range, where both lipid and protein for egg formation were derived from exogenous sources. Although our results were consistent with plasticity in resource-allocation strategies among sites (latitudinal variation), they did not support the seasonally variable nutrient threshold hypothesis within a site. We discuss the benefits of using both techniques simultaneously to assess reproductive strategies of birds that migrate between isotopically distinct areas. Une combinaison de l'analyse des isotopes stables et de celle de la composition corporelle pour évaluer les stratégies d'allocation des nutriments chez des individus reproducteurs de Melanitta fuscaRÉSUMÉ.-Les oiseaux comblent leurs besoins en énergie et en nutriments pour la formation des oeufs en utilisant des sources alimentaires (exogènes), des nutriments somatiques (endogènes) ou une combinaison des deux. Ainsi, comprendre la plasticité de l'acquisition des ressources et les stratégies d'allocation utilisées s'avère essentiel pour prédire la façon dont les changements écosystémiques à travers l'aire de répartition d'une espèce peuvent influer sur les paramètres démographiques. Les sources de nutriments pour les oeufs ont traditionnellement été évaluées par des analyses de la composition corporelle. L'analyse des isotopes stables constitue un nouvel outil pour les cas où les tissus des animaux diffèrent, sur le plan des isotopes, des chaînes alimentaires locales où ils se reproduisent. Nous fournissons la première comparaison simultanée de ces deux techniques et testons l'hypothèse d'un seuil des nutriments variable au cours de la saison. À l'aide d'une analyse de la composi...

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“…Nesting by Atlantic scoters at Redberry Lake was delayed only by about 3 days, but relative to other species scoters are relatively late nesters with slow-maturing broods Brown 1981, Brown andFredrickson 1997), and there is strong evidence that survival of scoter ducklings declines with advancing hatch date (Traylor and Alisauskas 2006). Thus, for scoters and other species with similar life-histories, the demographic consequences of even minor delays in breeding could be substantial and certainly can influence recruitment probability (Alisauskas and Kellett 2014).…”

Section: Carry-over Effects Related To Wintering Originmentioning

confidence: 93%

“…Two or more observers systematically searched for nests at Redberry Lake by walking line transects between mid-June and late July 2002-2004. We counted eggs, determined incubation stage by candling eggs (Weller 1956), and estimated initiation dates by back-dating, assuming a laying interval of 1.5 eggs per day (Brown and Brown 1981). Nesting females were trapped using hand-held nets after mid-incubation (~14 days incubation or later) and marked with a standard aluminum leg band.…”

Section: Field Methodsmentioning

confidence: 99%

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2014

The Condor

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Nesting Biology of the White-Winged Scoter

Cited by 34 publications

References 13 publications

Contaminants and sea ducks in Alaska and the circumpolar region.

Contaminants and sea ducks in Alaska and the circumpolar region.

Combining Stable-Isotope and Body-Composition Analyses to Assess Nutrient-Allocation Strategies in Breeding White-Winged Scoters (Melanitta fusca)

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