Sea Duck Populations Research Articles

Recent increase in annual survival of nesting female Common Scoter Melanitta nigra in Iceland

Despite their unfavourable conservation status, little is known about the population status, trends and demography of Common Scoter Melanitta nigra. Capture-mark-recapture (CMR) data from 154 recapture events of 88 individually marked breeding female Common Scoter Melanitta nigra in the Aðaldalur valley, northeast Iceland, during 2009–2018 generated an estimated annual apparent survival probability of 0.848 (95% CL 0.775–0.901). This exceeds a previous Icelandic CMR estimate (0.783, 95% CL 0.715–0.839) from nesting females during 1925–1958 at the nearby Mývatn (45 km to the SSE) when the population was declining at c. 2% per annum. Spring count data from Mývatn show that numbers of male and female Common Scoter at this important breeding site (thought to constitute over 80% of the Icelandic breeding national total) have increased by c. 1.8% per annum since 1974, and by 4–5% per annum since 2009. A population model showed that the observed change in survival corresponded well with the observed change in population growth rate. We reflect on causes of the increase in mean expected lifespan (from 4.1 to 6.1 years) between 1925–1958 and 2009–2018, speculating whether changes in food supply and/or reduction in gill-net fishing on Mývatn in the last 25 years could have been contributing factors to explain recent increases in breeding females there. An alternative, not necessarily mutually exclusive explanation could also be that the dramatic declines in chronic marine oil spill pollution in European waters could have contributed to higher recent female annual survival. While fully recognising the challenges of comparing survival rates from two sites in two different periods, survival rate has increased significantly between the two studies in a way that could potentially explain the increase in abundance at Mývatn. This could indicate that female survival has increased in the population as a whole. We strongly recommend demographic monitoring as a contribution to monitoring sea duck populations, species that are difficult to count and otherwise monitor annual changes in abundance in any meaningful way across large geographical ranges.

Spatial and temporal patterns of foraging activity by breeding Common Scoters (Melanitta nigra) in Scotland

Many populations of sea ducks have declined; poor foraging conditions in freshwater breeding habitats could be a contributory factor. The UK breeding population of Common Scoters (Melanitta nigra) declined by 63% between 1995 and 2007, prompting research which showed that lake use by breeding scoters was correlated with food abundance (large invertebrates) and accessibility (shallow water). Building on this earlier work, here we investigate scoter foraging activity at Scottish breeding lakes, in order to better understand declines and inform conservation measures. We hypothesised that foraging effort would (i) be concentrated in shallow water holding large invertebrates, (ii) differ between sexes, and (iii) vary through the season. We recorded scoter foraging activity during 208 c. one-hour watches, at 13 lakes over three years. Water depth and food abundance (invertebrates) were measured. Foraging was significantly associated with shallow water: areas within 10 m of lake shores, typically less than 0.9 m in depth, had 1.9 and 4.1 times more foraging use than expected by chance, for females and ducklings respectively.

Resource selection and wintering phenology of White-winged Scoters in southern New England: Implications for offshore wind energy development

AbstractSouthern New England provides key wintering habitat for White-winged Scoters (Melanitta fusca). This area has also pioneered the development of offshore wind energy in North America. The U.S. Bureau of Ocean Energy Management (BOEM) has established 9 Wind Energy Area (WEA) lease blocks along the Atlantic Outer Continental Shelf in areas that may provide important staging and wintering habitat for scoters and other species of sea ducks. Concern over the potential impact of offshore wind energy on sea duck populations has led to efforts to develop models to understand their distribution, habitat use, and site fidelity. We used satellite telemetry to document winter phenology and site fidelity, as well as fine-scale resource selection and habitat use, of 40 White-winged Scoters along the southern New England continental shelf. Scoters spent over half of the annual cycle on the wintering grounds and demonstrated a high degree of interannual site fidelity to composite core-use areas. Sizes of individual 50% core-use home ranges were variable (X¯ = 868 km2; range: 32–4,220 km2) and individual 95% utilization distributions ranged widely (X¯ = 4,388 km2; range: 272–18,235 km2). More than half of all tagged birds occupied 2 or more discrete core-use areas that were up to 400 km apart. Throughout the study area, scoters selected areas with lower salinity, lower sea surface temperature, higher chlorophyll-a concentrations, and higher hard-bottom substrate probability. Resource selection function models classified 18,649 km2 (23%) of the study area as high probability of use, which included or immediately bordered ~420 km2 of proposed WEA lease blocks. Future offshore wind energy developments in the region should avoid key habitats highlighted by this study and carefully consider the environmental characteristics selected by sea ducks when planning and siting future WEAs.

Sample size considerations for satellite telemetry and animal distributions

ABSTRACTSatellite telemetry is a powerful tool used to follow animals through their annual life cycle, informing the understanding of behavior and distribution of many species. Because boreal‐ and arctic‐nesting North American sea duck populations are challenging to survey, satellite telemetry is important for describing breeding distributions and identifying breeding population structure. Accurate knowledge of breeding distributions is needed for effective habitat and harvest management, but satellite telemetry is expensive so it is important to consider the effort necessary to accurately map breeding distributions. We construct 3 theoretical breeding distributions using existing telemetry data from 3 species of sea ducks, Barrow's goldeneye (Bucephala islandica), surf scoter (Melanitta perspicillata), and black scoter (M. americana), by fitting kernel densities to approximate breeding locations of individual birds. Then we determined the minimum sample size needed to approximate these theoretical breeding distributions by assessing the overlap between breeding densities simulated by sampling from the distributions and the theoretical breeding densities. Diminishing information gains with additional effort (i.e., <1–5% improvement in prediction) were reached with sample sizes ranging from 80 to 130. Sea duck mortality, transmitter failure, and exclusion of non‐breeding individuals resulted in an effective sample size smaller than the number of birds originally marked. For the cases we considered, obtaining breeding locations for 80–130 individuals would require marking 11–41% more birds than the sample size goal. Thus, although satellite telemetry provides valuable information on sea duck populations, our analysis suggests that accurately estimating the extent and relative use of breeding habitats requires substantial investment. © 2018 The Wildlife Society.

Ecology and Conservation of North American Sea DucksEcology and Conservation of North American Sea Ducksedited by Jean-Pierre L. Savard, Dirk V. Derksen, Dan Esler, and John M. Eadie.Studies in Avian BiologyNumber 46. 2015. Cooper Ornithological Society, and CRC Press, Boca Raton, Florida. xxii + 584 pp., 4 color plates, 98 text figures. $119.96 (hardcover). ISBN 13:978-1-4822-4897-5.

The editors of this volume have accomplished a remarkable assemblage of authors and topics on the sea duck tribe (Mergini) that has not been covered before in a single major treatise. While waterfowl (Anseriformes) are, arguably, the family of wild birds that have been most thoroughly studied by scientists, the sea ducks have been relatively poorly covered because of the remote habitats in which most of them are found at all times of the year. Only a few, such as the Common Goldeneye (Bucephala clangula), Barrow’s Goldeneye (B. islandica), Bufflehead (B. albeola), and Hooded Merganser (Lophodytes cucullatus) are accessible fairly easily to researchers. The other 11 extant species nest primarily in boreal, Arctic, or sub-Arctic habitats, and typically winter in even more remote oceanic locations. Nevertheless, waterfowl are one of the best inventoried of all North American birds, and sea ducks have been the subject of several additional surveys designed to monitor specific populations (Chapter 1). Most sea duck populations are uncommon, and many have been declining in number to the point that North American populations of two of the eiders, Spectacled (Somateria fischeri) and Steller’s (Polysticta stelleri), are listed under the U.S. Endangered Species Act. In Canada, eastern populations of Harlequin duck (Histrionicus histrionicus) and Barrow’s goldeneye (Bucephala islandica) are Species of Concern. The most significant upshot of this growing concern has been the formation of the Sea Duck Joint Venture of the North American Waterfowl Management Plan in 1998 (Sea Duck Joint Venture Management Board 2008, Sea Duck Joint Venture 2013). This has provided a superb forum for the sea duck specialists of the world to meet, plan, coordinate, and implement new science and to take other steps to stimulate progress in sea duck conservation. The 27 authors of this volume represent essentially all the individuals and government agencies and academic institutions that have driven the tremendous progress made since 1998. The fifteen chapters cover every major topic that one would expect. This is a departure from the more typical approach to taxonomic groups which usually cover each topic on a species-by-species basis. This was a thoughtful tactic as it encourages the broader community of scientists to integrate sea duck information into their analyses while, at the same time, provides important new perspectives for those more narrowly focused on waterfowl. Some new information is provided and the literature reviewed is thorough with all the common sources cited. In addition, a great deal of less common material is integrated by specialists in the general topics. These qualities contribute importantly to the editors’ central objective ‘‘to highlight

Avian Influenza Ecology in North Atlantic Sea Ducks: Not All Ducks Are Created Equal.

Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology.

Trends and population dynamics of a Velvet Scoter (Melanitta fusca) population: influence of density dependence and winter climate

As many seaduck populations around the world have been reported to be in decline, there is an increasing demand for knowledge about intrinsic and extrinsic factors determining population dynamics of these species. In this study, we analyzed long-term dynamics of the summer population of Velvet Scoters (Melanitta fusca) breeding in the Åland archipelago in the Baltic Sea; in particular, we examined the influence of winter weather and density dependence on population change. The studied population exhibited substantial fluctuations but only a weak negative trend during the total period of 58 years (1949–2007), and no significant trend at all during the latter three decades of the study (1977–2007). We tested for density dependence and incorporated the winter North Atlantic Oscillation index into the model to test for effects of winter conditions. Our final model explained 56.3 % of the variance of population growth of the studied population. Delayed density dependence explained 29.7 %, pre-breeding climate 8.3 %, and post-breeding climate 18.3 % of the variance. That breeding success is density dependent in a delayed manner is in accordance with the apprehension that Velvet Scoters breed at the age of 2 years. We conclude that density dependence and winter conditions must be taken into consideration when discussing population changes in seaducks in general and the Velvet Scoter in particular.

Abundance and Habitat Selection of Breeding Scoters (<em>Melanitta</em> spp.) in Ontario’s Hudson Bay Lowlands

Concern about declining populations of sea ducks counted on the wintering grounds prompted a survey of sea ducks on the breeding grounds in the Hudson Bay Lowlands of Ontario in spring 2009. We estimated densities of breeding scoters (Surf Scoter, Melanitta perspicillata, White-winged Scoter, M. fusca, and Black Scoter, M. americana) and found the average estimates of Surf Scoters (average = 0.11 indicated pairs/km2) and Black Scoters (average = 0.16 indicated pairs/km2) to be as high as some of the highest reported for North America. We also conducted a habitat association analysis using resource selection functions (RSF) for indicated pairs of all scoter species combined at a scale of 250 m. Breeding pairs of scoters in the Hudson Bay Lowlands appear to have an affinity for smaller wetlands (≤100 ha) disproportionate to what is available, also avoiding lakes (i.e., wetlands >100 ha). Pairs were also found in areas with less forest cover and fen area than was available. An estimate of the area under the curve of the receiver operating characteristic suggests that these habitat association models have some utility. Once tested and validated with surveys beyond the current study area, these models can be refined and used to predict habitat use by breeding pairs of scoters in the Hudson Bay Lowlands; this information will be particularly useful for population estimation and land use planning.

Changes in size and trends of North American sea duck populations associated with North Pacific oceanic regime shifts

Broad-scale multi-species declines in populations of North American sea ducks for unknown reasons is cause for management concern. Oceanic regime shifts have been associated with rapid changes in ecosystem structure of the North Pacific and Bering Sea. However, relatively little is known about potential effects of these changes in oceanic conditions on marine bird populations at broad scales. I examined changes in North American breeding populations of sea ducks from 1957 to 2011 in relation to potential oceanic regime shifts in the North Pacific in 1977, 1989, and 1998. There was strong support for population-level effects of regime shifts in 1977 and 1989, but little support for an effect of the 1998 shift. The continental-level effects of these regime shifts differed across species groups and time. Based on patterns of sea duck population dynamics associated with regime shifts, it is unclear if the mechanism of change relates to survival or reproduction. Results of this analysis support the hypothesis that population size and trends of North American sea ducks are strongly influenced by oceanic conditions. The perceived population declines appear to have halted >20 years ago, and populations have been relatively stable or increasing since that time. Given these results, we should reasonably expect dramatic changes in sea duck population status and trends with future oceanic regime shifts.

Energy-Based Carrying Capacities of Bufflehead Bucephala albeola Wintering Habitats

We present a model for calculating energy-based carrying capacities for bufflehead (Bucephala albeola), a small North American sea duck wintering in coastal and estuarine habitats. Our model uses estimates of the seasonal energy expenditures that incorporate site-specific energetic costs of thermoregulation, along with available prey energy densities to calculate carrying capacities in numbers of birds per winter. The model was used to calculate carrying capacities under several foraging scenarios for bufflehead wintering at three urban and three rural sites in the coastal northeast U.S. We found that energy-based carrying capacities varied from 20 - 320 birds per site per winter (0.38 - 6.22 birds per hectare), and showed a trend towards increasing with prey energy density (r = 0.53) and with decreasing average daily energy expenditure (r 2 = 0.57, p = 0.08). We found greater prey species richness at rural sites, but similar prey biomass and productivity across all sites. Bufflehead density averaged 1.89 ± 2.34 birds per hectare (range 0.38 - 6.22 birds per hectare) across the sites. Bufflehead abundance at urban sites was reduced by an average of 43.7% from that predicted using the relationship between per-hectare carrying capacity and bufflehead abundance at rural sites. This difference may arise from natural or human induced factors that act to limit sea duck populations on wintering habitats.

Predation rates, timing, and predator composition for Scoters (Melanittaspp.) in marine habitats

Studies of declining populations of sea ducks have focused mainly on bottom–up processes with little emphasis on the role of predation. We identified 11 potential predators of White-winged Scoters ( Melanitta fusca (L., 1758)) and Surf Scoters ( Melanitta perspicillata (L., 1758)) in North American marine habitats. However, of 596 Scoters marked with VHF transmitters along the Pacific coast, mortalities were recovered in association with just two identifiable categories of predators: in southeast Alaska recoveries occurred mainly near mustelid feeding areas, while those in southern British Columbia and Washington occurred mainly near feeding areas of Bald Eagles ( Haliaeetus leucocephalus (L., 1766)). Determining whether marked Scoters had been depredated versus scavenged was often not possible, but mortalities occurred more frequently during winter than during wing molt (13.1% versus 0.7% of both species combined, excluding Scoters that died within a postrelease adjustment period). In two sites heavily used by Scoters, diurnal observations revealed no predation attempts and low rates of predator disturbances that altered Scoter behavior (≤0.22/h). These and other results suggest that predation by Bald Eagles occurs mainly at sites and times where densities of Scoters are low, while most predation by mustelids probably occurs when Scoters are energetically compromised.

Patterns of use and distribution of king eiders and black scoters during the annual cycle in northeastern Bristol Bay, Alaska

Northeastern Bristol Bay, Alaska, which includes three large estuaries, is used by multiple sea duck species during the annual cycle. Limited aerial surveys indicate that this area supports tens of thousands of king eiders and black scoters during spring migration and the autumn molt. Existing satellite telemetry data were used to assess the temporal patterns of habitat use and spatial distribution of king eiders and black scoters in northeastern Bristol Bay throughout the annual cycle. King eiders used northeastern Bristol Bay during all months of the annual cycle and black scoters used the area during spring through fall. Both species exhibited a similar seasonal pattern of use that corresponded with the timing of life-cycle stages. Abundance of both species was highest during spring migration and the autumn molting period and lowest during summer. Use by king eiders did not occur during all winter months in every year of the study. King eiders were more broadly distributed than black scoters and were located farther from shore in deeper water. Core use areas had minimal overlap, suggesting a degree of spatial segregation between species and a preference for different habitats in northeastern Bristol Bay. Further study of potential variation in invertebrate community structure that may correlate with the observed interspecific spatial segregation in habitat use is needed to determine preferred forage and describe habitat requirements for each species. Such information is necessary to assess the potential impact that future anthropogenic or environmental changes may have on habitat quality of northeastern Bristol Bay and demography of Pacific sea duck populations that use this area.

Year-to-year correlations in blood metal levels among individuals of two species of North American sea ducks

Sea duck populations have declined in North America. Contaminants, especially metals, have been listed as possible contributing factors. Sea ducks are long-lived. Thus, individuals chronically exposed to elevated metal levels may be at greatest risk. Information about long-term exposure (≥1 year) of individuals to metals is absent. To address this information gap, we examined year-to-year correlations among individual White-Winged Scoters and King Eiders in levels of blood cadmium, lead, mercury and selenium. Positive correlations ( r ≥ 0.43), were found in six, five, five and two of seven correlations for cadmium, selenium, lead and mercury. Thus, certain individuals of these species may be exposed over two or more years to higher levels of cadmium, selenium and lead (but apparently not mercury) than other individuals. Single blood samples are appropriate metrics of exposure for studies that examine long-term effects of certain metals on these birds.

Survival of Common Goldeneye Ducklings in Interior Alaska

Duckling survival is an important component of waterfowl population dynamics, and we provide the first-known estimates of duckling survival for common goldeneyes (Bucephala clangula) at the northern limit of their range in Interior Alaska. We color-marked common goldeneye ducklings from 91 broods and radio-marked a subset of the females (n = 39) from a nest-box population in the boreal forest during the summers of 2002 and 2003. We monitored 46 broods in 2002 and 2003 combined and estimated daily survival rates (DSR) and survival to 30 days of age using program MARK. We modeled DSR in relation to year, linear trend across season, duckling age, female age, female body condition, initial brood size, and daily precipitation. Model-averaged duckling survival estimates from the mean yearly hatch date to 30 days of age were 0.64 (95% CI, 0.37–0.90) and 0.67 (95% CI, 0.54–0.80) for 2002 and 2003, respectively. Our best-approximating model indicated that survival differed by year and increased in a linear manner over the course of the 2002 season. Precipitation had a consistent negative effect on duckling survival in both years across models, whereas duckling age did not explain much of the variation in daily survival rates. In light of the decline of many populations of sea ducks, we suggest that more effort should be expended to obtain estimates of other population parameters for common goldeneyes, and monitoring programs should attempt to estimate populations more precisely to identify population-level changes in the future.

BLOOD LEAD LEVELS OF WILD STELLER'S EIDERS (POLYSTICTA STELLERI) AND BLACK SCOTERS (MELANITTA NIGRA) IN ALASKA USING A PORTABLE BLOOD LEAD ANALYZER

Sea duck populations are declining in Alaska. The reasons for the decline are not known; environmental lead exposure is one suspected cause. Thirty wild Steller's eider ducks (Polysticta stelleri) and 40 wild black scoter ducks (Melanitta nigra) were tested for blood lead levels using a portable blood lead analyzer (LeadCare; ESA, Inc., Chelmsford, Massachusetts 01824, USA). Sixty-seven and one-tenth percent of the sea ducks had undetectable blood lead levels, 30.0% had values indicating normal or background lead exposure, and 2.9% had values indicating lead exposure. None of the birds had values indicating lead toxicity, and no birds demonstrated clinical signs of toxicity. Birds in areas with higher human population density had higher blood lead levels than those in less densely populated areas. This is the first time a portable blood lead analyzer has been utilized with sea ducks in a field setting. Because it provides immediate results, it is valuable as a screening tool for investigators carrying out surgical procedures on birds in the field as well as establishing baseline blood lead data on sea ducks. Lead exposure does occur in wild sea ducks, and the study indicates that additional research is needed in order to determine the role environmental lead plays in declining sea duck populations.

Effekter av oljeutsläpp på övervintrande alfågel Clangula hyemalis vid Hoburgs bank i centrala Östersjön mellan 1996/97 och 2003/04

The Baltic Sea is an important marine area for wintering birds. Surveys in the 1990s showed that more than 25% of the European Long-tailed Duck Clangula hyemalis population wintered at Hoburgs bank and east of Gotland. A shipping route with very frequent traffic goes from southwest Baltic Sea via Öland, Hoburgs bank and east of Gotland to the Gulf of Finland. In year 2000 about 58,500 ships passed east of Öland along this route. Hundreds of oils spills are registered along the route each year. Weekly surveys of oiled birds at southern Gotland and analyses of birds that had drown in fish nets showed that tens of thousands of Long-tailed Ducks were injured by oil each year in central Baltic Sea. Of 998 birds that drowned in fish nets at Hoburgs bank 11.8% were found to have oil in the plumage. There was no clear relationship between the number of oiled birds observed and the number of registered oil spills in different years. Many sea duck have a life history in which variable or low productivity is compensated for by relatively high adult survival. This makes sea duck populations very susceptible to extra adult mortality caused by oil spills.

RESEARCH NOTES: EVIDENCE OF RECENT POPULATION INCREASES IN COMMON EIDERS BREEDING IN LABRADOR

Populations of several sea ducks are declining across their North American ranges (Sea Duck Joint Venture Management Board 2001), including populations of all 4 eider species (Somateria spp. and Polysticta steller; Kertell 1991, Stehn et al. 1993, Gratto-Trevor et al. 1998). Declines in common eider populations have been documented in Greenland, Hudson Bay, and Alaska (Robertson and Gilchrist 1998, Sudyam et al. 2000, Merkel 2004). Reasons behind these population decreases vary, and many are unclear. Factors identified as causing these declines include human disturbance, overharvesting, and climatic events (Robertson and Gilchrist 1998, Suydam et al. 2000, Merkel 2004). However, not all common eider populations in the north are decreasing; Christensen and Falk (2000) recently found evidence of population increase in an eider population in Northwest Greenland, while others have documented increases in Hudson Strait (Hipfner et al. 2001, Falardeau et al. 2003).

Biomarker responses in nesting, common eiders in the Canadian arctic in relation to tissue cadmium, mercury and selenium concentrations.

Populations of many North American sea ducks are declining. Biomarkers may offer valuable insights regarding the health and fitness of sea ducks in relation to contaminant burdens. In this study we examined body condition, immune function, corticosterone stress response, liver glycogen levels and vitamin A status in relation to tissue concentrations of mercury, selenium and cadmium in female common eiders during the nesting period. The study was conducted in the eastern Canadian arctic during July, 2000. Hepatic mercury, selenium and renal cadmium concentrations ranged 1.5-9.8, 6.5-47.5 and 74-389 microg/g, dry wt, respectively. Mercury concentrations were negatively related to dissection body mass, heart mass and fat mass. Cadmium concentrations were negatively related to mass at capture and dissection mass after controlling for the mercury concentration-dissection mass relationship. Cell-mediated immunity was assessed by the skin swelling reaction to an injection of phytohemagglutinin-P, and was unrelated to metal concentrations. After adjusting the corticosterone concentration to account for the time between capture and sampling, there was a negative relationship between the residual corticosterone concentration and selenium. Liver glycogen concentrations were not significantly related to metal concentrations. Mercury concentrations were positively related to those of hepatic retinol and retinyl palmitate and the ratio of the retinol to retinyl palmitate in liver. They were negatively related to the ratio of plasma to liver retinol. Our findings do not indicate that exposure to metals may have adversely affected the health of these birds. They do, however, suggest that more research is required to elucidate mechanisms by which exposure to these metals could impact body condition.

Modelling of Sea Duck Spatial Distribution in Relation to Food Resources in Lithuanian Offshore Waters Under the Gradient of Winter Climatic Conditions

The current study is the first attempt to apply geostatistical analysis in studying ecological relationship between populations of wintering sea ducks and communities of molluscs in Lithuanian offshore waters. Biological diversity of mollusc communities was found to have primary importance in determining spatial distribution of sea ducks under the most complicated winter climatic conditions, especially in the areas where sea duck populations were mainly feeding on molluscs. This finding strongly supports the earlier hypothetical assumption stating that under unfavourable winter climatic conditions large and dynamic sea duck populations are likely to over-exploit their benthic food stocks and the whole regional population of sea ducks is forced to gradually move towards the southwestern part of the Baltic Sea. The current study also proves that it is not the total biomass of certain mollusc species, but the average weight of mollusc specimens which is of a primary importance in determining spatial distribution of sea duck populations under extreme winter climatic conditions, especially in the areas where temporal sea duck concentrations are settled.

Wintering seaducks in Britian and Ireland: Populations, threats, conservation and research priorities

Abstract This paper provides a detailed review of the status and distribution of wintering seaducks (Scaup, Eider, Long‐tailed Duck, Common Scoter, Velvet Scoter and Red‐breasted Merganser) in Britain and Ireland. It is based on a literature review plus analysis of National Waterfowl Counts (NWC) and other data. A summary of current knowledge of wintering seaducks is provided together with information on threats to populations, conservation goals and research needs. Each species is examined in turn, with the emphasis on aspects of the population, habitat use, current distribution, trends and history. Important areas for individual species are highlighted. Overall, seaduck populations have changed considerably, those for Eider and Red‐breasted Merganser having expanded greatly, whilst those for Scaup, Common and Velvet Scoter have declined during historical and/or recent times. The trend for Long‐tailed Ducks is unclear. British population estimates are considered to be out of date and need to be revised. The premier areas for seaduck communities are highlighted, thus providing basic information for conservation action and future monitoring. Seaduck populations are threatened in a number of ways and the main factors are discussed. Oil pollution and the actions of commercial fisheries are the most important current threats. Conservation goals are suggested. These include an urgent need to develop appropriate domestic legislation to facilitate the protection of seaduck populations. Such legislation is currently almost entirely lacking. Some priorities for research, particularly for better population monitoring of seaducks in British and Irish waters, are provided. These include: alterations to the NWC scheme to allow the collation of opportunistic counts, made when the conditions are amenable for censusing seaducks; extension of the scheme into areas not currently surveyed (e.g. most parts of Ireland); and the establishment of intensive survey programmes to monitor seaducks in the key areas of Britain and Ireland. It is hoped that this paper will serve to stimulate interest and commitment from all who play a part in safeguarding our seaduck heritage.