Red-breasted Mergansers Mergus Serrator Research Articles

Long-term impact on the breeding birds of a semi-offshore island-based wind farm in Åland, Northern Baltic Sea

Breeding bird populations were monitored at a wind farm in the Båtskär area of the southern Åland archipelago in 2006–2017. The area is situated in the outer archipelago and comprises four islands with six wind turbines in total. The wind turbines began operating in autumn 2007. An environmental impact assessment for the area was conducted in 2002. A control area called Stenarna, located 22 km NW of Båtskär, was used for comparison. The Båtskär area annually recorded 850–1,050 pairs of breeding birds. Four species showed significantly decreasing trends in Båtskär, namely the Common Eider Somateria mollissima, Lesser Black-backed Gull Larus fuscus, Herring Gull L. argentatus , and Black Guillemot Cepphus grylle. In Stenarna, only the Common Eider significantly decreased over the same period. The Arctic Tern Sterna paradisaea increased in both areas, while the Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Common Gull Larus canus, Rock Pipit Anthus petrosus, and White Wagtail Motacilla alba increased in Stenarna, the control area. The Herring Gull population decline is unlikely to be related to the wind farm. However, the proximity of a wind turbine to a breeding colony of the Lesser Black-backed Gull has most likely contributed to its decline. The reason for the Black Guillemot decline in Båtskär is unknown. The decline of Common Eider in both areas may be connected to increasing predation from White-tailed Eagles Haliaeetus albicilla. Some species, such as the House Martin Delichon urbicum and auks, have benefitted from the wind farm construction. They can utilize new microhabitats created by the construction, while other species, such as the Common Eider, gain protection against predation because of human activities.

Behavioural responses of non-breeding waterbirds to marine traffic in the near-shore environment

ABSTRACT Capsule Recording of behavioural responses to ferry traffic for 11 target species showed that Red-throated Diver Gavia stellata, Slavonian Grebe Podiceps auratus, and Black-throated Diver Gavia arctica were most likely to react to passing vessels. Aim To provide information on how responses to marine traffic vary between waterbird species to inform marine spatial planning and environmental impact assessments in the near-shore environment. Methods We recorded behavioural responses to ferry traffic for 11 target species in near-shore waters: Common Eider Somateria mollissima, Goldeneye Bucephala clangula, Long-tailed Duck Clangula hyemalis, Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Black-throated Diver, Great Northern Diver Gavia immer, Red-throated Diver, European Shag Gulosus aristotelis, Slavonian Grebe and Black Guillemot Cepphus grylle. Responses were analysed using generalized linear models and mixed models. Results Red-throated Diver, Black-throated Diver and Slavonian Grebe were the most likely species to exhibit a response to passing vessels. While Red-throated Divers and Slavonian Grebes were highly likely to flush, Black-throated Divers and Great Northern Divers rarely took flight, instead favouring swim or dive responses. In rougher sea conditions birds were more likely to take flight, and the propensity to respond declined across the wintering period. Conclusions This research provides comparative evidence on the behavioural responses of waterbirds to marine traffic. The results support previous studies which highlighted the high sensitivity of diver species to disturbance and provide new evidence that Slavonian Grebe may also be a high sensitivity species.

Diversity and abundance of water birds in a subarctic lake during three decades

The numbers of divers, ducks, gulls, terns and waders in the 15 km2 oligotrophic lake Takvatn, North Norway were estimated six times during 1983-2012. Systematic mapping surveys were done by boat within the first week after ice-break in June. Twenty-one species were observed over the years and 12 were regarded as breeding on the lake. Red-breasted merganser Mergus serrator was the dominant diving bird, with estimated minimum number of pairs varying from 15 to 39 among years. Black-throated diver Gavia arctica (1-3 pairs), tufted duck Aythya fuligula (2-15 pairs) and common scoter Melanitta nigra (1-5 pairs) bred regularly, while velvet scoter Melanitta fusca (1-2) and goldeneye Bucephala clangula (2-4) were found in some years and mallard Anas platyrhynchos (1 pair) and wigeon Anas penelope (1 pair) in one year. Common gull Larus canus (6-30 pairs) and arctic tern Sterna paradisaea (2-35 pairs) bred in all years. Common sandpiper Tringa hypoleucos (3-9 pairs) and redshank Tringa totanus (1-4 pairs) were regular waders. Density variations of mergansers, gulls and terns are possibly related to density variations of three-spined sticklebacks Gasterosteus aculeatus, their dominant fish prey. The water birds are important links in the food web of the lake.

Distribution and numbers of wintering sea ducks in Swedish offshore waters

The first survey of seaducks covering the offshore waters of the entire Baltic was undertaken in 1992/1993, when, however, the Swedish waters were covered with relatively few ship surveys. The second all Baltic survey 2007–2011 included extensive aerial surveys of all Swedish offshore waters. This paper presents the Swedish data from these two surveys, supplemented with data from several other but partial surveys back to the early 1970s. The most numerous wintering seaduck in the Swedish waters was the Long-tailed Duck Clangula hyemalis with an estimated population of 1.41 million in 1992/1993, decreasing with 69% to 0.44 million in 2007–2009. Hoburg bank south of Gotland and the two Midsjö banks accounted for the vast majority of these ducks. In 2009–2011 only small numbers of scoters Melanitta fusca and M. nigra were found in Swedish Baltic waters. The totals for the Eider Somateria molissima and Red-breasted Merganser Mergus serrator were estimated at 20,000 and 8,000, respectively. Larger numbers of Eiders (50,000) and scoters (20,000) were found on the west coast.

Wintering Red-breasted Merganser Mergus serrator preying on pipefish in coastal Western Norway

De siste par år har nålefisker, for eksempel havnål, økt voldsomt i bestand og utbredelse. Den store og uvanlige økning er knyttet til et varmere hav, med økologiske tilstander som synes gunstige for denne gruppen fisk. Stor tilgjengelighet av nålefisker, spesielt havnål, har resultert i mange rapporter om at sjøfugl nyttiggjør seg dem som føde. I 2006 ble dette også observert av kysten av Vestlandet, der både svartbak og gråmåke prederte store nålefisker, sannsynligvis stor havnål (Håland 2006). Denne meddelelsen omtaler tilfeller av siland som fanger små nålefisker med stor effektivitet. Sannsynligvis var dette unge stadier av stor havnål, men det kan ikke utelukkes at det er andre arter nålefisk som er knyttet til de littorale, marine habitater. Observasjonene er kort diskutert i perspektiv av de endringer som nå skjer i havmiljøet og parallelle endringer i sjøfuglbestandene i nordøstre Atlanterhavet de siste årene, Nordsjøen inklusive. At silanda, som er å anse som en norsk ansvarsart i et europeisk perspektiv, kan nyttiggjøre seg nye byttedyr når havmiljøet endrer seg, er positivt sett i et forvaltningsmessig perspektiv.

Seabirds Foraging at Floating Seaweeds in the Northeast Atlantic

The influence of floating seaweed patches on the distribution and behaviour of seabirds was investigated using the European Seabirds At Sea database (ESAS). The percentage of observations that seabirds were observed with floating seaweed differed among species, depending on the mode of foraging. The results indicate that surface feeding species that make shallow dives (terns and Red-breasted Mergansers Mergus serrator) benefit most from the presence of floating seaweeds and their associated macro- and ichthyofauna. Species hunting for pelagic and bottom-dwelling prey (divers, Guillemots Uria aalge, Razorbills Alca torda, Puffins Fratercula arctica, Gannets Sula bassana and Cormorants Phalacrocorax carbo), and especially benthos feeders (Common Scoters Melanitta nigra and Eiders Somateria mollissima) were frequently seen in association with floating seaweeds, while opportunists and scavengers like gulls and skuas were recorded on few occasions. Petrels and shearwaters (surface-seizing, pursuit-plunging, pursuit-diving) were seldomly seen in association with floating seaweeds. The most common behavioural activities of the birds associated with floating seaweed were found to be surface pecking, actively searching, and pursuit plunging.

Changes in the waterbird community of the Lake Sevan–Lake Gilli area, Republic of Armenia: a case for restoration

Waterbird species richness (Gaviiformes, Podicipediformes, Pelecaniformes, Ciconiiformes, Phoenicopteriformes, Falconiformes, Anseriformes, Gruiformes, Charadriiformes, Passeriformes) has been significantly affected by a 19.5 m lowering of the water level in Lake Sevan (1933–2000), and the complete draining of nearby Lake Gilli (1960–2000) in the Republic of Armenia. Twenty-three former breeders are currently nonbreeders in the area. Four former breeders (black stork Ciconia nigra, glossy ibis Plegadis falcinellus, white-winged scoter Melanitta fusca, little crake Porzana parva) have been extirpated from the area. Four former nonbreeders (cattle egret Bubulcus ibis, red-breasted goose Branta ruficollis, sociable lapwing Chettusia gregaria, lesser black-backed gull Larus fuscus) have been absent from the area for at least 20 years. The red-breasted merganser Mergus serrator is the only former nonbreeder discovered breeding in the Lake Sevan basin. We recommend that management plans of the 1960s and 1970s be used to further develop and enact new efforts to increase the water level of Lake Sevan by at least 6 m, and that Lake Gilli and its surrounding wetlands be restored as a means of increasing waterbird species richness overall, and protecting regional populations of globally threatened or near-threatened species (Dalmatian pelican Pelecanus crispus, red-breasted goose Branta ruficollis, ferruginous pochard Aythya nyroca, white-headed duck Oxyura leucocephala, corn crake Crex crex, great snipe Gallinago media, black-winged pratincole Glareola nordmanni, white-tailed eagle Haliaeetus albicilla).

Abundance, distribution and habitat use of breeding Goosanders Mergus merganser and Red-breasted Mergansers Mergus serrator on British rivers

The abundance and distribution of breeding Goosanders and Red-breasted Mergansers were surveyed along river habitats throughout Britain in the spring and summer of 1987. Broad-scale habitat information was recorded and a total of around 9300 km of rivers was surveyed. The densities of Goosanders were highest in the Borders and northwest England, and those of Red-breasted Mergansers in the Highlands and western Scotland. The influence of river characteristics, including width, flow type, extent of bankside cover, elevation and gradient on the choice of habitats by sawbills was assessed using logistic regression models. River width had a significant influence on the presence of Goosanders and Mergansers, with wider river sections more likely to hold birds. The probability of recording Goosanders decreased with increasing river gradient while Mergansers preferred slower, smoother river sections. Taking these results into account, regional and national populations of both species were estimated by extrapolation from river sections surveyed to the total extent of river habitat available, as estimated by map measurements. Standing waters, by which both species nest, were not included in this survey. The limitations of this approach are discussed. National populations on river habitats were estimated to be 2600 (95% confidence limits CLs at 2333 and 2890) adult male and 3700 (95% CLs at 3272 and 4072) redhead Goosanders, and 800 (95% CLs at 562 and 1051) adult male and 750 (95% CLs at 562 and 964) redhead Mergansers.

Effects of human disturbance on broods of redbreasted mergansers Mergus serrator: J. Kahlert, Wildfowl, 45, 1994, pp 222–231

The effects of human disturbance on broods of Red-breasted Mergansers were studied at three Danish localities. Fast-moving boats (fishermen, windsurfers, and motor boats) were considered to have the greatest impact on Merganser broods a frequency of encounters and rate of disturbance were highest. The presence of fast-moving boats also caused the most significant modifications to time budgets. However, Merganser broods are considered quite resilient to human disturbance as they quickly resumed their former activities after disturbance, and at moderate disturbance levels, interruptions to comfort behaviour were compensated fro within 1 hours. However, on one locality with high disturbance levels and frequent high-speed boating, the survival of ducklings was reduced.

The effect of sediment dredging on the distribution of diving ducks at Lake Myvatn, Iceland

Sediment dredging in Lake Myvatn, Iceland, which commenced in 1967, poses a threat to the populations of breeding and moulting waterfowl in the area. Detailed mapping of diving ducks on the lake was carried out in order to evaluate the impact of the dredging. Densities of diving ducks in the dredged area were among the lowest in the lake. Positions of ducks diving for food were mapped in a 4·8-km 2 area in the North Basin of the lake, which included the area distrubed by dredging. In June 1990 relatively few dives were recorded in the dredged area except by red-breasted mergansers Mergus serrator. In August numerous dives were recorded in the dredged area, yet they were significantly fewer than outside the area. The loss of habitat is still small in comparison with fluctuations which occur in the breeding populations, but dredging in areas close to the present dredging activities will have a disproportionately large impact on the waterfowl populations.

Relationships of environmental contaminants to reproductive success in red-breasted mergansers Mergus serrator from lake Michigan

In 1977 and 1978, we studied red-breasted mergansers Mergus serrator nesting on islands in northwestern Lake Michigan to determine whether environmental contaminants were having effects on reproduction. Seventeen contaminants were measured in randomly chosen eggs from 206 nests under study. Using a variety of statistical approaches, we looked for effects of individuals contaminants and combinations of contaminants on reproductive measurements such as nest desertion, failure of eggs to hatch, death of newly hatched ducklings, percentage hatching success, number of ducklings leaving the nest and eggshell thickness. We also looked for relationships between the levels of some contaminants in blood samples of 39 incubating females and reproductive success. A small degree of eggshell thinning was attributed to DDE and a few other statistical tests were significant, but no contaminant or combination of contaminants we measured seemed to have a pronounced effect on the aspects of reproduction we followed.