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Breeding Eiders Somateria mollissima in the Baltic/Wadden Sea population have declined in recent decades, and several causes have been suggested. A recent study showed a modest increase in body mass from 2.20 kg by ca. 100 g during winter in Denmark, the main wintering area of the flyway population. This raises the question of whether Eiders could increase their body mass by an additional 200 g during pre-breeding to reach the average body mass of ca. 2.50 kg needed for successful reproduction. We analyzed this question by collecting Eiders at the Danish wintering grounds and pre-breeding grounds at Åland, Finland. Female Eiders increased their body condition (defined as scaled body mass index) from winter to the pre-breeding period, whereas males concurrently decreased in weight. The mean body mass of adult female Eiders was 2.23 kg in late winter, when they initiated spring migration. The mean female body mass at the pre-breeding grounds was 2.44 kg, an increase of 9.4% compared with females at the wintering grounds, while adult males decreased in weight by 3.4%. A decrease in gizzard mass was accompanied by a change in diet from large blue mussels Mytilus edulis at the wintering grounds to the small but more abundant mussels in the gizzard during pre-breeding. We conclude that female Eiders can reach a body mass of ca. 2.50 kg before breeding. Building up body condition for breeding is feasible at Åland; thus, difficulty in acquiring adequate resources for reproduction is unlikely to restrict local population size. [ABSTRACT FROM AUTHOR]

Contemporary climate change has complex effects on animal populations caused by the (non-linear) combination of multiple direct and indirect effects on individuals. These interactions make predictions of the ecological response to climate change challenging; however, predictive models are required to effectively manage wildlife populations and conserve biodiversity. Here, we demonstrate how agent-based models (ABMs) can be used to predict population responses under multiple effects of climate change. We consider the case of northern common eiders ( Somateria mollissima borealis ), a culturally and ecologically important seaduck which is experiencing dramatic environmental change due to losses in Arctic sea ice. Our model shows that losses in Arctic sea ice will lead to increases in nest predation by polar bears in areas where these species are sympatric. However, climate-mediated increases in breeding propensity and clutch size could have a large positive effect on eider population size. When considered together, these effects are predicted to result in a relatively stable eider population size over a 50-year period. Additionally, assuming eider populations are influenced by climate change in the manner proposed in this study, our model suggests that future eider populations will not be more susceptible to extrinsic perturbations (e.g. severe weather events, disease outbreaks) than were historical populations. As a result, our study demonstrates increasing climatic suitability and increasing nest predation will not lead to major changes in population size in northern common eiders, and emphasizes the importance of considering multiple, interacting effects on wildlife populations experiencing climate change. [ABSTRACT FROM AUTHOR]

ABSTRACT Common eiders ( Somateria mollissima) are large sea ducks with a circumpolar distribution and have high cultural significance to sport hunters and indigenous peoples in many countries. Their gregarious habits, including colonial breeding and forming large flocks during migration and winter, make eiders susceptible to environmental stressors during breeding and non-breeding seasons. Our objective was to assess whether low adult survivorship could be contributing to suspected local population declines in Nova Scotia, Canada. We banded molting male and breeding female common eiders along the marine coastline of Nova Scotia and recaptured them in later years. We found that from 1997 to 2011, when males and females were banded, male survival ( S) was high ( S = 0.92; 95% CI = 0.87-0.95), whereas female survival was approximately 10% lower ( S = 0.83; 95% CI = 0.78-0.87) and at a level comparable to what has been reported in other regions of the world where eider populations are thought to be in decline. Recovery rates ( f) of harvested male and female eiders were indistinguishable ( f = 0.013; 95% CI = 0.010-0.016), suggesting that lower female survival is attributable to factors other than hunting. Supplementary analyses using a longer-term data set for females only (1978-2011) and including live recapture data indicated that female survival rates have not changed markedly during the past 40 years and that the emigration rate from colonies is low (∼6%). We conclude that to successfully conserve this population, sources of non-harvest female mortality should be investigated and used to develop targeted management solutions. We speculate that one of those sources of mortality is predation on females at breeding colonies, notably from eagles and mustelids. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Hunting by humans constitutes a major source of mortality that selects for avoidance strategies. Group formation in eiders Somateria mollissima in response to hunting from motorboats was studied in the Danish Wadden Sea as an avoidance strategy to humans. In autumn the birds' food demand and energy consumption are relatively low and the need for optimal feeding opportunities are not as essential as during winter. We tested the hypothesis that eiders aggregate in groups of variable size dependent on predation risk (hunting), season and site. During autumn at the preferred feeding sites eiders occur in small numbers and group size increase together with hunting activity. Opposite during winter, eiders occur in large numbers and group size decrease when hunting activity increase. Hunting activity displaced eiders to adjacent sites with no or low hunting intensity and low food availability where group size of eiders increase during both autumn and winter in relation to the overall hunting activity. The formation into larger groups when hunting activity increase is probably due to increasing effects of vigilance and dilution, whereas formation into smaller groups is assumed to reduce the eiders conspicuousness to hunters. This change in group size made it possible for eiders to forage in areas with high food availability and high hunting intensity, while minimizing the risk of being detected by hunters. When the largest numbers of hunters were present at the preferred feeding site, group sizes during both autumn and winter were 110-125 eiders, indicating an optimal group size in relation to hunting density. Eiders located outside preferred feeding sites were in poorer body condition, suggesting that displacement was a suboptimal decision caused by hunting. We conclude that eiders adopted regrouping and displacement as two different strategies during hunting. Both strategies are tradeoffs between the risks of being detected by hunters and killed, and the benefits of feeding on mussel stocks thereby increasing body condition and hence fitness. [ABSTRACT FROM AUTHOR]

We provide the first report on trace element concentrations in eggs of common eiders ( Somateria mollissima ), a coastal benthic foraging sea duck, from Nova Scotia, Canada, and compare those to known values from this species elsewhere. Most trace elements of toxicological concern (Hg, Se, Cd, Cu, Zn) were lower in eider eggs from Nova Scotia than from eider eggs collected farther north in Canada, although As was elevated. Our data provide strong support for a pattern of increasing Hg at higher latitudes for this species. [ABSTRACT FROM AUTHOR]

Eiderdown has long been an important resource for northern cultures in the past but is overlooked in archaeology. Down, presumed to be from Eider ducks, has only been identified from a handful of high-status burials in Scandinavia. In order to test whether an archaeoentomological indicator for eiderdown production could be established, a survey of insects from two eiderdown productions sites in Iceland was conducted. The results identified over 500 duck fleas Ceratophyllus garei Rothschild and several beetle species from raw eiderdown and processing residue, as well as from pitfall traps placed in the floor of buildings where the down was stored and processed. It is argued that despite the fact that bird fleas parasitic on Eider ducks are not host-specific, their life history and microhabitat requirements, as well as the method employed to collect eiderdown, makes duck fleas a reliable indicator for eiderdown harvesting in archaeology. [ABSTRACT FROM AUTHOR]

The effects of an extensive bloom of the potentially toxic Prymnesium polylepis (Haptophyta) on breeding eiders (Somateria mollissima) in the Baltic Sea were analysed. Increasing abundances of the alternate stage P. polylepis was detected by a marine monitoring programme in the autumn 2007. The bloom peaked between March and May 2008 in the southern, central and northwestern Baltic Proper and abundances of up to 5×106 cells l−1 were recorded. At several sites P. polylepis constituted between 30 and 90% of the total phytoplankton biovolume. The flagellate was only recorded in low numbers in the northeastern Baltic Proper and Gulf of Finland. The abundances were low in 2007, 2009 and 2010. In 28 eider colonies situated in the southern and central Baltic Proper, sharp and synchronous declines in the number of nesting eiders were observed from 2007 to 2008. In colonies on Gotland in the central Baltic Proper, a 76% decrease, from 6650 nests to 1620 nests, was followed by increases in 2009 and 2010, although not up to numbers observed in 2007. At Utklippan and Ertholmene in the southern Baltic Proper, the observed decreases of 55%, from 144 to 65 nests, and 36%, from 1660 to 1060 nests, respectively, between 2007 and 2008, were followed by increases in 2009 and 2010 up to the level observed in 2007. By contrast, no general decline of the number of nesting eiders was observed from 2007 to 2008 in 75 colonies in the northeastern Baltic Proper and Gulf of Finland. Hence, the spatial distribution of the P. polylepis bloom in 2008 closely matched the observed distribution of extensive non-breeding of female eiders. We suggest that the intensive spring bloom of P. polylepis, either through a toxic or non-toxic pathway, affected the main benthic food of eiders, i.e. blue mussels (Mytilus trossulus × Mytilus edulis), at pre-breeding foraging sites close to the breeding sites, and, subsequently, the body condition of adult female eiders and their breeding propensity. [ABSTRACT FROM AUTHOR]

The southeast Beaufort Sea is a critical spring staging area for common and king eiders ( Somateria mollissima v-nigrum, S. spectabilis), and is for many the final stop before they reach their breeding grounds throughout the western Canadian Arctic. The region also has significant oil and gas potential, and the recent approval of a pipeline through the Mackenzie Valley may make development of these resources economically viable. We used satellite telemetry to determine the distribution and habitat use of eiders staging in the southeast Beaufort Sea in spring, and the overlap of eiders with oil and gas exploration. From 2004 to 2009, we monitored 51 eiders equipped with platform terminal transmitters (PTTs) throughout spring migration (May-June). We compared the marine habitats used by each species, and evaluated habitat preferences using resource selection functions. The location and extent of the flaw lead (open water along the interface between mobile pack ice and stationary landfast ice) at the time when eiders were staging varied among years, but both species showed a strong preference for use of flaw lead habitats. This preference was stronger for common eiders than for king eiders, which also used pack ice extensively. Common eiders generally occurred near the landfast ice edge, whereas king eiders were just as often nearer to the pack ice edge of the flaw lead. Average water depth (±SE) for common eiders was 22 ± 2 m compared to 30 ± 1 m for king eiders. Kernel density estimators showed that eiders generally occurred in lower densities in areas of otherwise suitable habitat off the Mackenzie River delta. We suggest that this is a result of the highly turbid water discharged by the Mackenzie River, which limits visibility. Oil and gas exploration overlapped significantly with the areas used by eiders. The high density of birds using the restricted and ice-rich flaw lead habitats indicates that an accidental spill in the region could be catastrophic for Canada's western Arctic eider populations. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Migratory birds that nest in the Arctic must be prepared to complete breeding within the brief polar summer, but must also have means of adjusting their physiological and behavioral readiness under widely variable environmental conditions. For Arctic breeding sea ducks, which may start laying within a week of accessing nest sites, hormonal status needed for courtship, pairbonding, and ovarian development must be achieved before arrival, often in the context of extreme and rapidly changing weather. Spectacled eiders ( Somateria fischeri) winter in pack ice, migrate to offshore openings in ice to await snowmelt on nest sites, and then move rapidly inland to start nesting. Using a camera that can film from a helicopter at high altitudes, we recorded behavior of spectacled eiders wintering in flocks containing tens of thousands of individuals within openings in Bering Sea pack ice, 70-90 km offshore. Rather than typical courting parties of single females pursued by a few males, the eiders formed crowded swarms of up to hundreds of birds in which males and females intermingled excitedly while performing courtship displays. In these 'courtship scrums,' which occurred in patches throughout very large flocks, it did not appear possible for one individual to track other individuals to assess their characteristics for mate selection. Instead, this previously unreported behavior, which occurred near the seasonal onset of courtship, may provide visual and auditory stimuli that accelerate hormonal development for rapid transition from harsh winter conditions to breeding readiness. Such deviations from typical behavior may facilitate adaptation to advanced phenologies in a warming climate. [ABSTRACT FROM AUTHOR]

Understanding how environmental factors affect ecological parameters is important to understanding and predicting impacts of environmental change. Given evidence and anticipated impacts of climate variability, this is especially true with respect to sea ice and its role in animal life history in northern regions. We examined relationships between the extent of consolidated spring ice cover (pack and landfast), nest initiation and clutch size in common eiders ( Somateria mollissima) in northern Labrador, a sub-Arctic region on the east coast of Canada. Our initial prediction was that eiders would delay nesting and have smaller clutches in years with more extensive spring ice cover. Between 1998 and 2003, we surveyed coastal islands for breeding eiders and collected information on nest age and clutch size. For those years, we estimated ice cover based on Radarsat-1 images supplied by the Canadian Ice Service during the spring period (approximately June 7-12). We found that spring ice cover was a significant positive predictor of nest initiation date, and the regression equation indicated that if the average extent of ice cover around nesting islands increased by 18 ha, average nesting date was delayed by approximately 1 day. Nest initiation date was a significant negative predictor of clutch size, and the regression equation indicated that a 20 day delay in nesting reduced average clutch size by approximately 1 egg. However, ice cover itself was not a significant predictor of clutch size. Our findings suggest that eiders breed when ice is present, but ice extent may negatively influence aspects of their breeding ecology. [ABSTRACT FROM AUTHOR]

Optimality theory predicts that both timing of arrival and arrival state on the breeding area will determine reproductive timing and investment in migratory organisms. We tested this idea using a condition-dependent individual optimization model ( Ardea, 1980, 225 and The American Naturalist, 1994, 698) in common eider ducks through descriptive data, path analyses and experimental manipulation. Our results support the causal pathways drawn from the optimization model indicating that individuals adjust their reproductive decisions as a function of their arrival date and body condition at arrival. Independent of body condition, early-arriving females had a longer pre-laying period, but still initiated their nests earlier, and produced larger clutches than late-arriving birds. Independent of arrival date, females in good condition laid earlier than those in poor condition. Manipulation of pre-laying female body condition confirmed that the relationship between condition and laying date was causal. Female common eiders appear to optimize reproductive decisions in response to both their external (i.e. environmental conditions affecting the egg-value) and internal (i.e. body condition) states. These adjustments seem to minimize the fitness costs of reproduction, in which higher clutch size is not associated with an apparent lower survival or future breeding probability. Our study emphasizes the importance of (i) simultaneously considering the timing of migration, the state of individuals and the seasonal change in egg-value to understand clearly birds' breeding decisions and (ii) appreciating the potential proximate and ultimate factors explaining why some individuals delay breeding and/or produce small clutches. [ABSTRACT FROM AUTHOR]

Lacking experience represents a constraint on solitary breeding, which may be overcome by joining groups of more experienced breeders. Also, biological market theory predicts preference for partnerships with conspecifics of the highest value. We examined the formation of cooperative brood-rearing coalitions in facultatively social eider females, Somateria mollissima. Our aim was to elucidate the hitherto neglected role of age on female group size and condition differences within groups, and to explore whether older females represent attractive coalition partners. Based on previous work, we hypothesized that older breeders are found in smaller groups, and that the attraction of older partners would override the predicted negative effect of differences in body condition on female group size. We found that older females occurred in smaller groups and that the negative relationship between condition differences and group size became less steep with increasing age of the oldest group member. We also found that the maximum body condition found in a brood-rearing coalition increased with the age of the oldest female, despite a sharp decline in the probability of the oldest individual being the one in best condition. These results demonstrate the importance of age in the formation of cooperative brood-rearing coalitions and the increase in female quality with age. The experience of older females is a valuable commodity, which attracts younger prospective coalition partners in good condition regardless of body condition differences. Our results illustrate the general principle that grouping decisions cannot be understood by viewing partner choice criteria in isolation. [Copyright &y& Elsevier]

Abstract: Parasitological investigations on 40 gulls (Larus), 15 eiders (Somateria) and some birds of shelduck (Tadorna), curlew (Numenius), oystercatcher (Haematopus) and terns (Sterna) resulted all in all 7 coccidia and about 76 helminth species, partly residenting in different hosts and often in enormous quantities (Somateria 160.000, Tadorna 58.000, Larus 62.000, Numenius 93.000). Effects of helminthal loads upon the avian hosts, biology of parasites and correlations between their coastal and inland places of residence are in discussion. Morphological differences of Psilochasmus in Tadorna tadorna, of Gymnophallus from gallbladders of Larus too, furthermore the structural change of egg-forming Gymnophallida in the gut of Somateria mollissima and coccid oocysts from kidneys of Larus argentatus, Haematopus ostralegus, Tadorna tadorna and Somateria mollissima are showed. [Copyright &y& Elsevier]

To maximize fitness, animals must respond to a variety of processes that operate at different rates or timescales. Appropriate decisions could therefore involve complex interactions among these processes. For example, eiders wintering in the arctic sea ice must consider locomotion and physiology of diving for benthic invertebrates, digestive processing rate and a nonlinear decrease in profitability of diving as currents increase over the tidal cycle. Using a multi-scale dynamic modelling approach and continuous field observations of individuals, we demonstrate that the strategy that maximizes long-term energy gain involves resting during the most profitable foraging period (slack currents). These counterintuitive foraging patterns are an adaptive trade-off between multiple overlapping rate processes and cannot be explained by classical rate-maximizing optimization theory, which only considers a single timescale and predicts a constant rate of foraging. By reducing foraging and instead digesting during slack currents, eiders structure their activity in order to maximize long-term energetic gain over an entire tide cycle. This study reveals how counterintuitive patterns and a complex functional response can result from a simple trade-off among several overlapping rate processes, emphasizing the necessity of a multi-scale approach for understanding adaptive routines in the wild and evaluating mechanisms in ecological time series. [ABSTRACT FROM AUTHOR]

The Norwegian coast is a very important winter area for king eiders ( Somateria spectabilis), but their origin has been unknown. We determined spring and autumn migration routes, timing of migration and potential breeding areas of king eiders wintering in north-eastern Norway using implanted satellite transmitters. Five males and five females were equipped with transmitters in February 2008, and location data were received from six birds. All birds departed within 10 days in mid April and flew to the Pechora Sea and Kara Sea in western Russia where they staged until mid June. Subsequently, four of five birds with active transmitters (two females and two males) moved east to potential breeding locations on the Gydan and Taymyr Peninsulas. In early July, the males moved west to moult at Kolguyev Island and in the Pechora Sea. The two females departed in mid July, one probably moulting between the gulfs of the Ob and Yenisei Rivers, after which it moved to the Pechora Sea. The other female probably moulted in the eastern Taymyr, thereafter moving to Novaya Zemlya. This female returned to the north-eastern coast of Norway 1 December, while the other female returned 2 January. For the males, the transmitters stopped in December/January when they were still in the Pechora/Kolguyev area. King eiders wintering in north-eastern Norway thus originate from the western half of Arctic Russia, and the Taymyr Peninsula is probably the dividing point between the eastern and western flyways. [ABSTRACT FROM AUTHOR]

Here I report on glaucous gulls ( Larus hyperboreus), an opportunistic, generalist predator, stealing bivalves from a diving duck, the common eider ( Somateria mollissima). The study took place in spring, the pre-breeding period of the common eider, in an Arctic fjord (Adventfjorden) at western Spitsbergen, Svalbard. Eiders were abundant, their presence predictable, and they fed on large prey requiring surface handling—all factors facilitating food theft. Only adult glaucous gulls attended the eider flocks. The glaucous gulls brought stolen prey ashore. Amongst these the bivalve Mya neoovata (Myidae) was common. The probability that an eider flock was attended by glaucous gulls declined as the season progressed and increased with the foraging activity of the eiders. Eider flock size and the degree of aggregation within flocks were poor predictors of gull presence. However, eider flocks attended by a single gull were smaller than flocks attended by more than one gull. Common eiders are capital breeders which build up large energy reserves prior to breeding. Kleptoparasitism, therefore, may have a negative impact on eider energy acquisition in early spring. For the glaucous gull, kleptoparasitism may be important as few other food sources are available this time of the season. [ABSTRACT FROM AUTHOR]

Abstract: In many coastal regions oil spills can be considered to be one of the most important risks for the coastal environment. Efficient contingency management in responding to oil spills is critically important. Strategic priorities in contingency management highly depend upon the importance attributed to different economic and ecological resources such as beaches or birds. Due to the lack of a market for natural resources in the real world, these resources cannot be directly measured in monetary terms. This increases the risk that natural resources and their services are neglected in contingency decision making. This paper evaluates these natural resources in a hypothetical market by using the methodology of stated choice experiments. Results from a pilot survey show that according to the perspective of individuals, an oil spill combat process should focus on the protection of coastal waters, beaches and eider ducks. [Copyright &y& Elsevier]

This article examines the state of current approaches to the governance of common pool resources (CPRs), the impacts of the recent emergence of the partnership paradigm, and the consequences for the management of CPRs. These issues are explored through a case study of the Wash European Marine Site partnership, where a Public Inquiry recently upheld the refusal of the conservation agency to grant mussel cultivators permission to scare eider ducks off their lays using sonic bird-scaring devices. As a result, the relationship between the conservation agency and the mussel cultivators has been severely damaged, causing a “fracturing” of the partnership. Through this case study the article explores the contradictions involved in statutory partnerships and asks if it is possible to use partnerships to empower local communities while the state remains in overall control. [ABSTRACT FROM AUTHOR]

Abstract: Although the Danish Wadden Sea is of international importance for several bird species, large-scale blue mussel Mytilus edulis fishing took place from 1984–1987, ceasing thereafter due to low mussel stocks. Mussel fishing removes much of the blue mussel biomass, especially larger individuals. Hence we predict that intensive mussel fishing will affect their predators, such as the Eider Somateria mollissima, which is predominantly a blue mussel feeder by, 1) reducing the amount of blue mussels in their diet relative to alternative prey items, 2) exploitation of smaller blue mussel shell classes, 3) loss of body condition, 4) changing feeding distribution to aggregate to the remaining mussel stocks, and 5) decreasing numbers. Before winter 1986/87 blue mussel biomass was estimated at 40,600 tons, decreasing to 15,400 tons in 1987/88 due to mussel fishery. We collected Eiders in both periods to monitor their diet and body mass and used aerial surveys to determine changes in numbers and distribution. Between the two periods, blue mussels declined in the Eiders diet, numbers of Eiders with empty stomachs increased and the mean length of blue mussel taken by Eiders decreased. Eider body condition declined from 1986/87 to 1987/88, mostly the result of the reduction in numbers of individuals with blue mussel remains in their gizzards and in better body condition compared to those taking alternative food items or having empty gizzards. Eiders shifted their distribution from the southern part of the Danish Wadden Sea to the northern part, where the remaining blue mussel stocks were situated. Eider numbers were lowest in 1987/88, the year of lowest blue mussel stocks. We conclude that intensive mussel fishery affected the Eider''s diet, reduced their body condition and affected distribution and abundance. The results also showed that availability of blue mussels may have a key role in building up and maintaining body condition in Eiders during winter. [Copyright &y& Elsevier]

1. Many migratory birds are assumed to remain fairly stationary during winter. However, recent research indicates that mid-winter movements are evident in a variety of bird species, and the factors causing individuals to move are poorly understood. 2. We examined the winter movements of 95 individual king eiders ( Somateria spectabilis, L.) tracked with satellite transmitters in the Bering Sea between 2002 and 2006 to explore whether environmental factors such as day length, location, sea ice, and habitat quality could explain the occurrence of winter movements longer than 50 km. 3. We used a novel algorithmic random forest model to assess the importance of variables predicting whether a bird remained or departed from a wintering site. 4. We found extremely high individual variability in winter movement decisions by king eiders, and the individual bird was the most important variable followed by location, date, and sea ice concentration. 5. We conclude that individual strategies exist that interact with environmental conditions to form multiple movement patterns. 6. While a minor proportion of winter movements may be forced by environmental conditions, we propose that many winter movements may be of an exploratory nature where individuals aim to acquire information about alternative wintering sites that may enhance their survival probability at some point in time when environmental fluctuation renders their preferred wintering site unsuitable. [ABSTRACT FROM AUTHOR]

In long-lived species, adult survival is the population parameter having the highest elasticity, and therefore, it can be expected to be least affected by climatic variations. We studied the dynamics and survival of breeding female common eiders Somateria mollissima mollissima in the Baltic Sea from 1960 to 2007. Using nest censuses and capture–recapture methods, we investigated: (1) the annual apparent survival (φ) of breeding females, (2) the survival-mediated population fluctuation, (3) weather effects on survival, and (4) long-term population trends. Based on capture histories of 6,393 females, average φ was 0.882 (95% confidence interval 0.864, 0.899). We found no relationship between population growth rate and survival. Furthermore, the highest ranking models, based on Akaike’s information criterion, indicated no effect of the North Atlantic Oscillation index on the φ of eider females. Population size, assessed from nest counts, has been steadily declining since 1985. Despite the long time series (48 years), the overall variation in the φ rates remained comparatively narrow, at maximum ranging only 10% between 2 consecutive years. Results imply that declining female survival is not the driving force behind the population decline, and we hypothesize that the overall poor fledging success and the consequent low recruitment explain the decreasing trend of nest densities since 1985. [ABSTRACT FROM AUTHOR]

Abstract: [1.] In species that actively maintain optimal conditions for offspring development, the quality of the breeding site may have a substantial effect on reproductive effort and breeding success. Here, we studied the effect of nest shelter on reproductive costs for incubating female common eiders (Somateria mollissima) nesting in an arctic environment using both a correlative and an experimental approach. [2.] The correlative data showed that females that nested in naturally well-sheltered nests experienced milder temperatures, laid larger clutches, provided a more favourable thermal environment for their eggs and had a higher hatching success than those at exposed nest-sites. [3.] We added artificial shelters to exposed nest-sites and compared them to unmanipulated exposed nest-sites to examine the effect of nest shelter in females of similar quality. Costs of nesting in exposed sites were greater as evidenced by the reduced female mass loss and more favourable thermal conditions for the eggs at artificially sheltered nest-sites relative to exposed nest-sites. However, there was no difference in hatchings success between artificially sheltered and exposed nest-sites. [4.] This study shows even small changes in the climatic conditions at the nest-site can have substantial consequences for reproductive effort, but the association between nest-site quality and breeding success in eiders is due to better quality individuals occupying better nest-sites. [Copyright &y& Elsevier]

The article offers information on multiple spring migration strategies in a population of Pacific Common Eiders. It highlights better understanding of the life histories and implications for conservation. It also discusses the distinct migration strategies that vary in terms of duration, staging locations, and arrival dates in the nesting areas. Birds will migrate into less favorable headwinds if the probability of tailwinds is low. Risk of mortality associated with ice movement in each of the migration strategy was also taken into account.

The article focuses on feeding activity of Common Eiders wintering in the Southwest Greenland Open Water Area. Behavioral observations were made at a fjord habitat and an outer coastal habitat. Eiders were identified as diurnal feeders in the coastal area where hunting and fishing was common. Meanwhile, eiders fed only during twilight and at night in the fjord area. During daylight hours, experienced adult birds in the fjord did not attempt feeding. Large communal roosts indicate that nocturnal feeding maybe common throughout the fjords in Southwest Greenland.

The article discusses a study which investigated the relative importance of factors affecting brood-rearing area selection by Common Eiders according to duckling age in New Brunswick. The sufficiency of food resources is believed to be the main criterion during selection of brood-rearing sites. Rockweed abundance seems to have only limited effect on habitat use by Common Eiders. Meanwhile, a gradual slope is beneficial for foraging ducklings. Common Eiders avoided high concentrations of Herring Gulls, because predation was minimal. The noted decline in duckling abundance may be explained by increasing boat traffic on Grand Manan Island.

The article discusses a study which investigated causes of duckling disappearance and to evaluate the impact of gull predation on the reproductive success of Common Eiders breeding on Stratton Island, a tern restoration site in southwestern Maine. The researchers suggested that additional gull control measures, particularly at a nearby gull colony, may enhance duckling survival. Monitoring of other eider colonies is recommended in the region to better assess duckling survival and recruitment areas.

Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which forms extensive blooms during the summer in the Baltic Sea. Nodularin was detected in liver, muscle and/or feather samples of several common eiders (Somateria mollissima) from the Gulf of Finland (northern Baltic Sea) in 2002-2005. Published information on the adverse effects of NODLN in marine birds is scarce. The aim of this study was to evaluate the toxicity of NODLN, and determine the concentrations of NODLN in liver and muscle tissue in mallards (Anas platyrhynchos) exposed to N. spumigena. Mallards received a single or multiple exposure via oral gavage with an aqueous slurry containing toxic N. spumigena. Dosages ranged from 200 to 600 µg NODLN per kg body weight (bw). There were minimal histopathological changes in liver tissue, and brain cholinesterase activity did not differ among treatment groups. Concentrations of NODLN measured by LC-MS in liver varied between approximately 3-120 µg kg-1 dry weight (dw) and ducks receiving multiple exposures had significantly greater liver toxin levels than ducks receiving the two lowest single exposures. In muscle, NODLN concentrations were approximately 2-6 µg kg-1 dw, but did not differ significantly among exposure groups. This is the first in vivo lab study examining the effects and bioaccumulation of NODLN from N. spumigena in birds. The mallards in this study were resistant to adverse effects and did not bioaccumulate substantial levels of NODLN at the doses given. [ABSTRACT FROM AUTHOR]

1. With the aid of a novel survivorship model, an 8-year field study of social and maternal factors affecting duckling survival in eiders ( Somateria mollissima) revealed that duckling survival probability varies in accordance with maternal brood-rearing strategy. This variability in survival provides compelling evidence of different annual fitness consequences between females that share brood-rearing and those that tend their broods alone. Consequently, as prebreeding survival is often a major source of individual variation in lifetime reproductive success, a female's annual, state-dependent (e.g. condition) choice of a brood-rearing strategy can be a critical fitness decision. 2. Variance in duckling survival among lone tender broods was best explained by a model with significant interannual variability in survival, and survivorship tending to increase with increasing clutch size at hatch. Clutch size was correlated positively with female condition. Hatch date and female body condition together affected duckling survival, but their contributions are confounded. We were unable to identify a relationship between female age or experience and duckling survival. 3. Variance in duckling survival among multifemale brood-rearing coalitions was best explained by a model that included the number of tenders, the number of ducklings and interannual variation in how their ratio affected survivorship. Hatch date did not significantly influence survival. 4. Expected duckling survival is higher in early life for lone tenders when compared with multifemale brood-rearing coalitions. However, as ducklings approach 2–3 weeks of age, two or three females was the optimal number of tenders to maximize daily duckling survival. The survivorship advantage of multifemale brood-rearing coalitions was most evident in years of average survival. 5. The observed frequency distribution of female group sizes corresponds with the distribution of offspring survival probabilities for these groups. Evidence for optimal group sizes in nature is rare, but the most likely candidates may be groups of unrelated animals where entry is controlled by the group members, such as for female eiders. 6. Our study demonstrates that differences in social factors can lead to different predictions of lifetime reproductive success in species with shared parental care of self-feeding young. [ABSTRACT FROM AUTHOR]

Coastal and offshore waters of Southwest Greenland are internationally important wintering areas for king eiders ( Somateria spectabilis) breeding in eastern Canadian Arctic and in northwestern Greenland. This paper presents the first assessment of their winter diet. Based on esophageal-proventricular samples from 26 females (13 juveniles and 13 older birds) and 15 males (11 juveniles and four older birds) collected in 2000–2002 (November–May) in coastal waters of Nuuk, we identified 28 prey species. The diet consisted of almost equal proportions (aggregate fresh mass) of polychaetes, echinoderms, crustaceans and molluscs. The dominant prey species were Pectinaria spp . (26.8%), Strongylocentrotus droebachiensis (18.4%), Mya eideri (11.2%) and Hyas araneus (9.7%). The polychaetes have previously been identified as important prey for eiders in Greenland, but apparently not outside Greenland. Compared with a diet study of common eiders Somateria mollissima from the same wintering area, the king eiders consumed significantly less bivalves and significantly more echinoderms. This difference corresponded with observations that common eiders were feeding in shallow waters, while king eiders were feeding in deeper waters farther from the shore. Benthic surveys are needed to confirm that diet corresponds with prey availability. [ABSTRACT FROM AUTHOR]

We assessed population genetic subdivision among four colonies of Common Eiders (Somateria mollissima v-nigrum) breeding in the Yukon-Kuskokwim Delta (YKD), Alaska, using microsatellite genotypes and DNA sequences with differing modes of inheritance. Significant, albeit low, levels of genetic differentiation were observed between mainland populations and Kigigak Island for nuclear intron larnin A and mitochondrial DNA (mtDNA) control region. tntercolony variation in haplotypic frequencies also was observed at mtDNA. Positive growth signatures assayed from microsatellites, nuclear introns, and mtDNA indicate recent colonization of the YKD, and may explain the low levels of structuring observed. Gene flow estimates based on microsatellites, nuclear introns, and mtDNA suggest asymmetrical gene flow between mainland colonies and Kigigak Island, with more individuals on average dispersing from mainland populations to Kigigak Island than vice versa. The directionality of gene flow observed may be explained by the colonization of the YKD from northern glacial refugia or by YKD metapopulation dynamics. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine associations between persistent organic pollutants and vitamin A (retinol), retinyl palmitate and vitamin E status (α-tocopherol) in two species occupying different trophic positions in the Arctic food web. Levels of polychlorinated biphenyls (PCBs), some selected organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) were analyzed in yolk sac of newly hatched chicks of Brünnich''s guillemot (Uria lomvia) and common eider (Somateria mollissima) from Kongsfjorden, Svalbard (Norwegian Arctic) (79°N). Morphological variables were measured, and levels of retinol, retinyl palmitate and α-tocopherol were analyzed in plasma and liver. Brünnich''s guillemot had significantly higher levels of POPs than common eider, as expected from its higher trophic position. Morphological traits seemed to be negatively related to POPs in Brünnich''s guillemots, but not in common eiders. In Brünnich''s guillemot, negative relationships were found between some OCPs (hexachlorobenzene, oxychlordane, p,p′-DDE) and liver α-tocopherol levels. The negative relationships between these OCPs and liver α-tocopherol levels in Brünnich''s guillemot hatchlings became less evident when the confounding effect of liver mass was corrected for. In common eider positive relationships were found between summed PCB (ΣPCBs) and some OCPs (β-hexachlorocyclohexane, oxychlordane) and liver α-tocopherol levels. Differences in relationships between POPs and vitamin status in the two species may be related to differences in POP exposure levels linked to their trophic position in the Arctic marine food web, or to intrinsic physiological differences between the species. [Copyright &y& Elsevier]

Abstract: Immunity is hypothesized to share limited resources with other physiological functions and may mediate life history trade-offs, for example between reproduction and survival. However, vertebrate immune defense is a complex system that consists of three components. To date, no study has assessed all of these components for the same animal model and within a given situation. Previous studies have determined that the acquired immunity of common eiders (Somateria mollissima) is suppressed during incubation. The present paper aims to assess the innate immune response in fasting eiders in relation to their initial body condition. Innate immunity was assessed by measuring plasma nitric oxide (NO) levels, prior to and after injection of lipopolysaccharides (LPS), a method which is easily applicable to many wild animals. Body condition index and corticosterone levels were subsequently determined as indicators of body condition and stress level prior to LPS injection. The innate immune response in eiders did not vary significantly throughout the incubation period. The innate immune response of eiders did not vary significantly in relation to their initial body condition but decreased significantly when corticosterone levels increased. However, NO levels after LPS injection were significantly and positively related to initial body condition, while there was a significant negative relationship with plasma corticosterone levels. Our study suggests that female eiders preserve an effective innate immune response during incubation and this response might be partially determined by the initial body condition. [Copyright &y& Elsevier]

Along the central Beaufort Sea, Pacific Common Eiders (Somateria mollissima v-nigra) nest on unvegetated, barrier islands; often near nesting Glaucous Gulls (Larus hyperboreus). Nest-site choice likely reflects a strategy of predator avoidance: nesting on islands to avoid mammalian predators and near territorial gulls to avoid other avian predators. We observed a nesting colony of Common Eiders from first nest initiation through nesting termination on Egg Island near Prudhoe Bay, Alaska (2002-2003). Resident gulls depredated many eider nests, mostly during initiation. All nests failed when an Arctic Fox (Alopex lagopus) visited the island and flushed hens from their nests, exposing the eggs to depredation by the fox and gulls (resident and non-resident). Common Eiders actively defended nests from gulls, but not from foxes. Likely all three species (i.e., eiders, gulls, and foxes) ultimately achieved negligible benefit from their nest-site selection or predatory activity: (a) island nesting provided no safety from mammalian predators for eiders or gulls, (b) for Common Eiders, nesting near gulls increased egg loss, (c) for Glaucous Gulls, nesting near colonial eiders may have reduced nest success by attracting the fox, and (d) for Arctic Foxes, the depredation was of questionable value, as most eggs were cached and probably not recoverable (due to damage from fall storms). Thus, the predator-prey interactions we observed appear to be a case where little or no fitness advantage was realized by any of the species involved. [ABSTRACT FROM AUTHOR]

1. Wind energy is a fast-growing renewable energy source and many offshore wind parks will be erected in shallow waters (< 40 m deep) where various coastal bird species are found. The two main issues regarding offshore wind farms and birds are disturbance and collision risk. We studied the effect of wind turbines on the flight behaviour of wintering common eiders Somateria mollissima in order to identify the properties that cause disturbance and the factors that may increase their risk of collision. 2. The study was conducted at Tunø Knob offshore wind park in the Kattegat, Denmark. We attracted birds though the use of decoys located at increasing distances from the wind park. To discriminate between the potential disturbance effect of the standing towers from that of the revolving rotor blades, wind turbines were switched on or off alternately during 10 experimental trials. 3. Common eiders reacted strongly to the presence of wind turbines. The number of flying birds was significantly related to flight corridor location and position of the decoy group. That behavioural reaction was interpreted to be a consequence of their high speed and low-manoeuvrability flight occurring within the vertical height range of the wind turbines. The number of landing birds also reacted to the position of the decoy group in relation to proximity to the turbines, with the greatest effects observed within the wind park. Such avoidance behaviour might decrease use of otherwise suitable habitat. 4. The movement and noise of rotors affected neither the number of common eiders flying within corridors nor the number of birds reacting to decoys. This suggests that the avoidance behaviour observed was caused by the presence of the structures themselves and that eiders use vision when avoiding human-made structures. 5. Synthesis and applications. This study has demonstrated that common eiders avoid flying close to or into the Tunø Knob wind park. This behaviour may result in a reduction in habitat availability within and around wind parks, and raises concerns about the possible impact of the extensive development of large-scale wind parks in shallow offshore waters, which are the main feeding areas for sea ducks and other marine birds. Our results indicate that the disturbance effect of revolving rotor blades is negligible during daylight hours but highlights the need for studies to be carried out during hours of darkness and conditions of poor visibility (e.g. fog and snow). Until more insight is gained, we recommend caution when planning wind parks in areas of high sea duck densities. [ABSTRACT FROM AUTHOR]

Populations of Pacific common eiders (Somateria mollissima v-nigrum) breeding in Alaska, USA, have declined markedly over the past 40 years. We studied survival of adult female Pacific common eiders using capture-recapture of nesting hens at 3 sites on the Yukon-Kuskokwim Delta (YKD), Alaska from 1994 to 2004. We used data consisting of 268 recapture events from 361 uniquely marked individuals to investigate temporal, geographic, and environmental variation in adult female survival. Our results suggest apparent annual survival of adult eiders from the YKD was high (0.892, SE = 0.022) and spatially and temporally invariant (σ² = 0.005), a pattern consistent with other long-lived marine birds. Moreover, our results suggest adult survival may be functionally fixed for Pacific common eiders, and at the present, adult survival may be relatively unresponsive to environmental or management perturbations. Our data did not support hypothesized variation in survival relative to mortality factors such as predation on breeding grounds, physiologic costs of reproduction, and wintering conditions. Although changes in adult survival likely have a large potential effect on prospective population growth, our results suggest viable management actions aimed at increasing survival may be extremely limited. [ABSTRACT FROM AUTHOR]

There has been wide empirical and theoretical interest in how diving animals allocate time between obtaining oxygen at the surface and foraging at depth. Assuming diminishing returns in oxygen gain at the surface, classic diving models predict that time on the surface should increase, while time spent foraging at depth should first increase and then decrease as travel time increases. Controlled laboratory experiments have indicated partial support for predictions of diving models; however, their usefulness in understanding patterns of diving behaviour in the wild is still in question. We assessed the applicability of diving models to foraging patterns of common eiders, Somateria mollissima sedentaria, wintering in the Canadian Arctic. Underwater footage was used to quantify time foraging at depth and duration of surface pauses in relation to changes in travel time induced by strong tidal currents. Consistent with predictions of diving models, bottom foraging time decreased with increasing travel time, while total dive duration was relatively constant at 58.47±5.32s, close to the estimated aerobic dive limit for this species. However, durations of surface pauses were not associated with diving parameters, as anticipated from diving models. Durations of surface pauses were highly variable (183.05±158.06s) and often considerably longer than necessary to replenish oxygen stores. While the duration of surface pauses predicted by diving models in relation to travel time may be an optimal strategy when obtaining oxygen at the surface is the predominant constraint to foraging, a variety of processes operating at different timescales can influence behavioural patterns in the wild. Preliminary analysis considering the rate of digestive processing suggests that foraging patterns of eiders could be simultaneously influenced by several different rate constraints. Therefore, while static modelling approaches are an important heuristic tool for elucidating mechanisms underlying diving behaviour, dynamic approaches, which can incorporate variables concerning multiple physiological and environmental states, will probably be required to fully understand complex foraging patterns observed in the wild. [Copyright &y& Elsevier]

Abstract: Immunity is believed to share limited resources with other physiological functions and this may partly account for the fitness costs of reproduction. Previous studies have shown that the acquired immunity of female common eiders (Somateria mollissima) is suppressed during the incubation fast. To save energy, triiodothyronine (T3) is adaptively decreased during fasting in most bird species, despite T3 levels are maintained throughout incubation in female eiders. However, the relationship between thyroid hormones and the immune system is not fully understood. The current study aimed to determine the endocrine mechanisms that underlie immunosuppression in incubating female eiders. To this end we assessed the effects of exogenous T3 on both components of the acquired immune system in 42 free-ranging incubating birds. Half of the females were implanted with T3 pellets, while the other half sham implanted served as control. We measured variations in the immunoglobulin index, the T-cell-mediated immune response, body mass, and plasma parameters in both groups before and after manipulation. T3 levels in implanted females were four times higher and mass loss was 40% greater than in control females. Implanted females also showed an 18% decrease in the immunoglobulin index, while the T-cell-mediated immune response was not significantly affected by the treatment. Finally, the treatment did not induce any significant changes in corticosterone levels. Our study shows that exogenous T3 decreased only one component of the acquired immune system. We suggest that the immunosuppressive effect of T3 could be mediated by its effects on body fat reserves. Further experiments are required to determine: (1) the relationship between adiposity and immune function, (2) the adaptive significance of immunosuppression during incubation in eiders. [Copyright &y& Elsevier]

Decreased risk of predation is a key benefit of group living, and selfish herd theory predicts competition for the relative safety of central positions. Spatial position also affects behaviour, as individuals trade-off their feeding and vigilance to mitigate the risk of predation. Female eiders, Somateria mollissima, often pool their broods and share brood rearing, and anti-predatory vigilance is a core parental care activity. Females are assumed to trade-off vigilance and feeding, as efficient recovery of condition is crucial for energetically stressed postincubating females. Evidence shows that a female''s own ducklings are closer to her than unrelated young in amalgamated broods and that predation of ducklings by gulls is edge biased, so a female''s spatial position should correlate with the survival prospects of her brood. We identified determinants of female spatial position (aggression, structural size, body weight, age, clutch size) within multifemale brood-rearing coalitions, and explored whether spatial position affected female activities. Female aggression frequency was the only significant predictor of centrality in brood-rearing coalitions, and female age was positively associated with aggression. Investment in vigilance, but not investment in feeding, increased with spatial centrality; instead, central females devoted less time to other activities (resting, preening and moving). We conclude that central eider females do not need to trade-off vigilance and feeding. Heavy body weight did not guarantee a favourable position in brood-rearing coalitions, which may help explain our previous finding that female eiders in best body condition when their brood hatches tend their brood alone. [Copyright &y& Elsevier]

Members of breeding groups face conflicts over parental effort when balancing antipredatory vigilance and feeding. Empirical evidence has shown disparate responses to manipulations of parental effort. We develop a model in which we determine the evolutionarily stable effort of partners given their body conditions, allowing the benefits of shared care to be unevenly divided, and we test this model's predictions with data on common eiders (Somateria mollissima). Eiders show uniparental female care; females may share brood rearing, or they may tend alone, and their body condition at hatching of the young shows large environmentally induced variation. The model predicts that parental effort (vigilance) in a coalition is lower than when tending alone, controlling for parental condition; this prediction is supported by the data. The parental effort in a coalition should be positively correlated with body condition, and this prediction is also supported. Finally, parental effort should increase when partner condition decreases and vice versa; this prediction is partially supported. The Nash bargaining game may provide promising avenues by which to determine the precise settlement of reproductive skew and effort between coalition partners in the future. [ABSTRACT FROM AUTHOR]

An induced immune challenge can have two counteracting effects on an individual's reproductive investment. (1) The resource demand could increase to ''fuel'' the immunologic reaction, which in turn can lead to an adaptive decrease in investment in resource-costly activities, such as reproduction. One the other hand, (2) the individual could assume that the immune activity it experiences is indicative of a serious infection. The latter can lead to an adaptive increase in reproductive investment in response to the reduced prospects of survival and future reproduction, so called "terminal investment." To measure such life-history-related consequences of increased immune activity, one group of incubating female Common Eiders (Somateria mollissima) was injected with a nonpathogenic antigen (sheep red blood cells, SRBC) while controls were injected with sterile saline. The eider is a long-lived sea-duck. Females, who incubate the eggs and care for young without assistance from the male, engage in facultative anorexia during incubation leading to a large reduction in body mass. Eiders can abandon their young to other females at the cost of reduced young survival. The immune challenge resulted in a larger mass loss, a prolonged incubation period, and reduced return rate, demonstrating both short-and long-term costs of immune challenge. Additionally, in response to what might have been interpreted as reduced survival chances in immune-challenged females, these females more often tended their own brood after hatching, despite having suffered higher costs during incubation. [ABSTRACT FROM AUTHOR]

Abstract: One adaptive significance of immunosuppression during reproduction can be explained by the immunopathology-avoidance hypothesis. This hypothesis states that since heat shock proteins (HSP) are highly conserved proteins found in both pathogen and host, and are expressed at a higher level during reproduction, the risk of autoimmunity is then increased, HSP being the target of the host’s immune response. Reduced immunocompetence has been attributed to hormonal regulation, in particular by glucocorticoids. The current study aimed at testing the immunopathology-avoidance hypothesis and the implication of corticosterone in incubating fasting common eiders (Somateria mollissima). To this end, we have measured immunological and stress indicators including immunoglobulin (IgY), HSP70, HSP60, and corticosterone levels in breeding females. A multivariate general linear model analysis showed that female body condition, IgY, HSP70, and HSP60 levels were the main variables explaining the model. Females showed a significant decrease by 15% of their IgY index during incubation. Conversely, HSP70 and HSP60 levels significantly increased by 12 and 10%, respectively throughout incubation. Moreover, there was a positive significant relationship between both HSP whereas HSP60 levels were negatively correlated to IgY index. Plasma corticosterone levels showed a tendency to decrease during incubation. We conclude that these findings are consistent with the immunopathology-avoidance hypothesis in breeding eiders. Nevertheless, the long-term reproductive costs and the underlying mechanisms of such an immunosuppression remain to be determined and will require further experiments. [Copyright &y& Elsevier]

Endogenous reserves influence both survival and reproduction of many waterfowl species, but little is known about reserve levels of most species during the nonbreeding season, particularly those wintering at high latitudes. We investigated whether age, sex, and season were related to carcass composition of northern common eiders ( Somateria mollissima borealis) wintering in southwest Greenland during 1999–2002. Adults carried more lipid and protein than juveniles during all winters. Among both age classes, males and females had similar fat levels but males carried slightly more protein. There was no dramatic seasonal variation in lipid or protein content. This suggests that during the period of this study, these eiders did not experience large-scale nutritional shortfalls. As predicted, Greenlandic eiders carried more lipid reserves than eider populations wintering in more temperate environments. Contrary to prediction, there was little relation between reserve levels and photoperiod, ambient temperature, or hunting disturbance intensity. Our results suggest that both sexes are equally capable of dealing with nutritional deficits, and that juvenile birds are more prone to nutritional stress as evidenced by their consistently poorer body condition. [ABSTRACT FROM AUTHOR]

Abstract: Mass mortalities of common eiders Somateria mollissima have been ascribed to high parasite loads. However, the actual role of parasites in mortalities is disputed as in the case of a mass mortality of eiders in the Wadden Sea in the winter of 1999/2000. A critical evaluation of the role of parasites in eider mass mortalities is hampered by (1) a lack of data on actual parasite loads of the birds involved, (2) missing regional data for comparison, and (3) a lack of unbiased samples: investigations are often based on dead beached individuals, which are presumably the more heavily infected birds of a population and thus more likely to die and be washed ashore. Although published data on parasite loads in birds of the winter 1999/2000 mortality are available, no data on background parasitism in eiders from the Wadden Sea exist, making an evaluation of the potential role of parasites in this mortality event difficult. By investigating endoparasites of 102 eiders affected by an oil spill in the northern Wadden Sea in winter 1998/1999, we provide a data set of background parasitism in wintering eiders from the Wadden Sea. We found 13 different parasite taxa with high prevalence values (% infected birds) in the acanthocephalan Profilicollis botulus, the nematode Amidostomum acutum, cestodes and trematodes. In some taxa we observed pronounced differences in prevalence values between juvenile eiders and adults, as well as between adult sexes. The parasite composition shows that bivalves, crabs (Carcinus maenas) and other crustaceans are important sources of infections by being intermediate hosts. This is partly mirrored in the food content of eider stomachs where bivalves and crabs were predominantly found. Intensities of the acanthocephalan P. botulus, suspected of causing eider mortalities, were especially high in juveniles (1112±416 ind per infected host), but lower in adult males (40±7) and adult females (81±18). However, no extraordinary mortality event was observed in the winter of 1998/1999, indicating no or a very weak effect of the parasites on host condition. A comparison with the parasite loads of eiders from the mass mortality in the winter of 1999/2000 shows that parasite numbers were by no means exceptional for birds from the area. Hence, parasites alone are unlikely to have caused this mortality. Regional background parasite loads are important to differentiate between primary and secondary roles of parasites in anomalous mortality events. [Copyright &y& Elsevier]

Altered body condition, increased incubation costs, and egg loss are important proximate factors modulating bird parental behavior, since they inform the adult about its remaining chances of survival or about the expected current reproductive success. Hormonal changes should reflect internal or external stimuli, since corticosterone levels (inducing nest abandonment) are known to increase while body condition deteriorates, and prolactin levels (stimulating incubation) decrease following egg predation. However, in a capital incubator that based its investment on available body reserves and naturally lost about half of its body mass during incubation, corticosterone should be maintained at a low threshold to avoid protein mobilization for energy supply. This study focused on the regulation of corticosterone and prolactin release in such birds during incubation, when facing egg manipulation (control, reduced, or increased) or a stressful event. Blood samples were taken before and after clutch manipulation and at hatching. Corticosterone levels were determined before and after 30 min of captivity. Female eiders exhibited a high hypothalamic-pituitary-adrenal sensitivity, plasma concentration of corticosterone being increased by four- to fivefold following 30 min of captivity. The adrenocortical response was not modified by body mass loss but was higher in birds for which clutch size was increased. In the same way, females did not show different prolactin levels among the experimental groups. However, when incubation started, prolactin levels were correlated to body mass, suggesting that nest attendance is programmed in relation to the female initial body condition. Moreover, due to an artifactual impact of bird manipulation, increased baseline corticosterone was associated with a prolactin decrease in the control group. These data suggest that, in eiders, body mass and clutch size modification can modulate prolactin and corticosterone levels, which cross-regulate each other in order to finely control incubation behavior. [ABSTRACT FROM AUTHOR]

In bird species, one of the trade-offs between reproduction and survival appears in the parental decision to desert the nest. Nest desertion is modulated by several factors including clutch size. However, the incubation stage at which predation occurs is also an important factor. In this study, we examined whether nest desertion was linked to initial clutch size, partial clutch predation (final clutch size) and the incubation stage at which it happened in a capital breeder: the female common eider ( Somateria mollissima) nesting in the high Arctic. The study was performed in Kongsfjorden in 2002 on the western coast of the Svalbard Archipelago (78°55′N, 20°07′E). We observed that nest desertion was higher when the initial clutch size was small. Also, females deserted their nests more during the first third of incubation than later. Thus, as incubation proceeded, nest desertion was less likely to occur even after egg reduction. Our results pointed out that this parental decision in female eiders seemed to depend on initial clutch size and on the date into incubation of clutch reduction. [ABSTRACT FROM AUTHOR]

Abstract: Concentrations and total organ content of mercury, selenium and cadmium, as well as liver, kidney and body mass were determined in female common eiders from 1997 to 2000 at the East Bay Migratory Bird Sanctuary in the eastern Canadian arctic. In 1997 and 1999, female eiders were collected during the pre-nesting period when they eat copious amounts of food and gain substantial weight in preparation for the rigours of nesting. In 1998 and 1999, female eiders were collected during the mid to late stages of the nesting period when they eat very little, if at all, and, as a consequence undergo dramatic weight loss. Total body mass, liver mass and kidney mass were highest in pre-nesting birds, especially in 1997. They were significantly lower in nesting birds collected in 1998 and 2000. In contrast, mercury and cadmium concentrations were lowest in pre-nesting birds collected in 1997 and 1999 and increased to significantly higher concentrations in nesting birds collected in 1998 and 2000. In contrast to these results, the total contents of mercury in liver and cadmium in kidney did not change significantly over the 4-year period. Hepatic selenium concentrations were relatively stable over the 4-year study period while changes in the total content of selenium in the liver paralleled changes in liver mass and body mass. The results suggest that mercury and cadmium concentrations in female common eiders change in response to normal changes in body and organ mass that occur during the reproductive period. Thus, it may be important to consider body condition or reproductive stage when using common eiders (and perhaps other species of sea ducks) in biomonitoring studies or when interpreting concentrations of metals in tissues in terms of the risk they pose to these ducks. [Copyright &y& Elsevier]

This article focuses on a survey which presents an evidence of recent population increases in common eiders breeding in Labrador and Newfoundland. Populations of several sea ducks are declining across their North American ranges, including populations of all 4 eider species. Factors identified as causing these declines include human disturbance, overharvesting, and climatic events. Labrador has breeding populations of the northern common eider, the American common eider and intergrades of the 2 subspecies. Researchers documented this zone of overlap, but the geographic extent and consequences for population structure and recruitment have not been fully explored. In 1998, the Canadian Wildlife Service in conjunction with the Labrador Inuit Association, initiated surveys on the Labrador coast to collect information to estimate breeding eider population trends. Results based on islands surveyed a minimum of 4 years showed an average apparent annual increase of 2 1.6% for Nain, 13.4% for Hopedale, and 18.1% for all areas over the 6-year period from 1998 to 2003.