Abstracts of presentations
Seaduck Specialist Group Meeting
Workshop on scoters
29 November – 3 December 2000
Mols, Jutland, Denmark
Convened by the Wetlands International Seaduck Specialist Group
and National Environmental Research Institute, Denmark
SCOTER WORKSHOP ABSTRACTS
Participants to the workshop were asked to provide abstracts from their talks before the meeting, so that we could prepare a booklet of these for participants on the day. Obviously, not all authors had the time or opportunity to prepare these, and some authors have been kind enough to provide abstracts even though they have been unable to attend the meeting. At present (May 2002) we are still working hard on laying out the final report of this meeting which we plan to produce as a National Environmental Research Institute Report, and which is half completed. We apologise for the long delay in its production caused by the heavy work burden placed upon our report production team, and hope in the meantime these abstracts will be of general interest and give some idea of what was discussed at the meeting.
1. Changes in the numbers and distribution of breeding Velvet Scoter in Sweden
Åke Andersson, Swedish Association for Hunting and Wildlife Management, Bäcklösavägen 8, S-756 51 Uppsala, Sweden.
Trends in the breeding population of Velvet Scoter along the Swedish coast are summarised based on data from the Stockholm Archipelago, and from censuses recently carried out in other parts of the country. Factors affecting the population will be discussed.
2. The status of Common Eider and scoters in the Northern Black Sea
Tatiana Ardamatskaya, Azov-Black Sea Ornithological Station, Golaya Pristan Kirova, 17-2 Ukraine.
Velvet and Common Scoter are both very rare in the Northern Black Sea region. The Common Eider has become a common regular breeding species on the islands of Yagorliskyi Bay since 1975, and since 1988 has expanded to colonise the islands of Tendrovskyi Bay. In 1988, pairs also began nesting on islands in Djarilgachskyi Bay and on the lagoons behind the Kinburnskyi Spit. The Eider has thus become the most abundant breeding Anatidae species in the Northern Black Sea, numbering some 2000 nesting pairs and a wintering population of 2500 individuals.
3. Distribution and migration of sea duck populations wintering on the southern coast of the Barents Sea: hazards in relation to oil development
Jan-Ove Bustnes & Geir Helge Systad, NINA, Department for Arctic Ecology, Polarmiljøsenteret, N-9296 Tromsø, Norway.
The southern coast of the Barents Sea is a wintering area for populations of sea ducks of local, Russian and Arctic origin. These areas are now being subject to off shore oil drilling. In order to document sea duck species composition, numbers, winter distribution and migration times, we made four aerial surveys between September and early May of the whole Norwegian Barents Sea coast. Key areas of sea ducks were identified. The most numerous species were Common and King Eiders. Wintering populations of mergansers, long-tailed ducks and scoters were generally low throughout the winter. Steller’s Eiders were confined to Varangerfjord. The numbers of eiders increased from September to November, but the density of sea ducks was highest in February/March. At that time we observed more than 50 000 Common Eiders and 30 000 King Eiders. A large proportion of the eiders followed spawning shoals of Capelin Mallotus villosus. In April, the numbers of sea ducks had dropped drastically and all King Eiders, and most Common Eiders had left the areas. This study indicate great movements of sea ducks throughout the winter in the Barents Sea, and the very high densities can be expected associating with the spawning areas of Capelin. These areas may, however, change between years. Along several sections of the Barents Sea coast, oil spills will be catastrophic at the time when the highest concentrations of sea ducks occur.
4. Nocturnal flight activity of sea ducks near the windfarm Tunø Knob in the Kattegat
S. Dirksen1, I. Tulp1, H. Schekkerman2, J. K. Larsen3, J. van der Winden1, R.J.W van de Haterd1, P. van Horssen1 & A.L. Spaans2, 1Bureau Waardenburg bv, P.O. Box 365, 4100 AJ Culemborg., The Netherlands, 2Alterra, Wageningen, The Netherlands, 3National Environmental Research Institute (NERI), Kalø, Denmark
The Dutch Government wishes to advance the development of wind energy in the North Sea. As a result, there is a need to understand the effects wind turbines may have upon birds in nearshore and offshore situations. One of the gaps in our current knowledge concerns the diurnal and nocturnal flight activity of wintering sea ducks in the vicinity of turbines. Since no offshore Dutch windfarms exist at present, this study was carried out at Tunø Knob, 7 km offshore in the Danish Kattegat.
The questions to be addressed in this study were: (1) Do sea ducks show nocturnal flight activity? (2) Does the windfarm influence the flight pattern of ducks in the area at night? (3) How do Eiders, flying in the immediate vicinity of the windfarm, respond to wind turbines?
Nocturnal radar observations, visual observations and surveys from an observation tower located close to the windfarm, as well as ship-based radar and visual observations, were used to collect data on the nature and intensity of nocturnal flight activity of Eiders in the vicinity of the windfarm. Studies of Eiders and Common Scoters were conducted in a similar site without turbines. The methods used and results obtained will be discussed.
The project yielded new information on nocturnal flight behaviour of sea ducks in situations with and without wind turbines. These results seem to be in line with earlier comparable studies on land and in fresh waters and show that species actively avoided wind turbines, even those that are not used to encountering obstacles in their flight path in their natural habitat. In the application of the results from this study to the planning of windfarms at sea, the following conclusions are most important:
(1) Eiders and Common Scoters were nocturnally active, but in dark periods flight intensity was far less than in moonlit periods. The total number of potential collision victims is the product of flight intensity and the probability of collision. To arrive at accurate estimates of potential number of victims, measurements of collision risks in various light conditions are necessary.
(2) Eiders actively avoided the vicinity of the windfarm in their flight movements, decreasing the risk of collision.
(3) An avoidance effect of the windfarm was detected up to 1500 m from the park. We cannot predict whether this avoidance distance would be similar or greater in the case of larger windfarms.
(4) The reduced flight activity in the vicinity of the windfarm and the low number of flight movements through the park indicate that windfarms can act as flight path barriers. This effect is probably related to park size. Whether or not this effect restricts birds from reaching favoured feeding and resting areas depends on the size and the local situation of the windfarm, relative to resting and feeding sites. Long linear windfarms could therefore exert a greater effect in this respect.
The results of this study can be applied in decision-making about windfarms in the North Sea. Local studies, addressing the particular problems of the locality, however, remain essential if the results from this Danish study are to be applied in the appropriate way. Knowledge of the local flight patterns and intensity during the night as well as the relative location of roosting and feeding areas of sea ducks is essential to determine and minimise risks to birds. Recommendations are made for the decision-making process regarding windfarm development in the North Sea.
5. Population dynamics of Scoters
Tony Fox, Department of Coastal Zone Ecology, National Environmental Research Institute, Kalø, Grenåvej 12, DK-8410 Rønde, Denmarktfo@dmu.dk
The scoters are unusual amongst the Northern Hemisphere diving ducks. They lay large clutches relative to their body mass and incubate for extended periods. As a consequence, from the few published studies, they are successful nesters, although success at fledging young depends heavily on the available food supply and may vary enormously between years. Breeding female scoter apparently moult remotely from the breeding areas, and at least some undertake extended moult migrations to ultimate wintering grounds to regrown new flight feathers. There is some evidence of some winter segregation of the sexes, with females wintering south of the males. It is interesting to speculate whether the heavy investment in clutches, moult migration and the seeming remote wintering areas of adult females all conspire to enhance asymmetry in survival rates of the sexes which may explain the surfeit of males in the population as a whole.
6. Migration routes and distribution of Scoters in the Western Palearctic
Tony Fox & Stefan Pihl, Department of Coastal Zone Ecology, National Environmental Research Institute, Kalø, Grenåvej 12, DK-8410 Rønde, Denmarktfo@dmu.dk; email@example.com
We are a long way from being able to describe the abundance and distribution of Common and Velvet Scoters in the Western Palearctic, but from the results gathered for this meeting, we have progressed a long way forward. We present data from ringing recoveries, counts and the Wetlands International International Waterfowl Census Seaduck Database, together with the newest information compiled for this meeting, to give an overview of the distribution and abundance of these two species, with particular emphasis on the wintering and moulting concentrations.
7. Seaduck Specialist Group Scoter Workshop 2000
Tony Fox & Stefan Pihl, Department of Coastal Zone Ecology, National Environmental Research Institute, Kalø, Grenåvej 12, DK-8410 Rønde, Denmarktfo@dmu.dk; firstname.lastname@example.org
Scoters are the forgotten taxa amongst the waterfowl of the Northern Hemisphere. Very little is known about their numbers, distribution and ecology. With increasing pressure from human activity in shallow offshore waters, it is evident that conflicts with moulting and winter seaduck concentrations will increase in the immediate future. As a result, we need to know more about their ecology and population dynamics if we are to be able to predict the effects of these changes to their habitats. The Scoter workshop aims to gather the most up-to-date available information relating to breeding, moulting and wintering distribution and abundance of the Common Scoter Melanitta nigra and Velvet Scoter Melanitta fusca and attempt to suggest best practice for the future monitoring of these populations. Sessions on population dynamics and food and feeding ecology will attempt to address more specific questions regarding the effects of local environmental change on abundance and distribution. The results of case studies will also be presented that provide limited information relating to the effects of fast ferry traffic and wind turbine construction to scoter behaviour and distribution. The objective is to produce a major publication from the workshop as a source document for these species.
8. Spring Scoter migration along the coast of Kamchatka, Russia.
Yuri Gerasimov & N. Gerasimov, Kamchatka Institute of Ecology, Russian Academy of Sciences, Rybakov 19A,Petropavlovsk-Kamchatsky 683024, Russia.
Studies of the spring migration of waterfowl have been carried out along the coastline of Kamchatka since 1975, concentrating on counts of flying birds to estimate species number and the intensity and timing of migration. Between 1990 and 2000, 6 count episodes (three on east and three on western coasts) of 22-37 days duration were carried out during the peak seaduck migration period within 10 km of the coastline. On the west coast, between 140,000 and 167,000 scoters (Common and Velvet Scoters combined) were counted in all. On the basis of these observations, we tentatively estimate the spring passage along the western coast of Kamchatka to involve 200,000 Common Scoter and 100,000 Velvet Scoter. The maximum number counted on the east coast was 40,000 individuals, but the observations are currently insufficient to estimate the numbers passing this coast. It is hoped that these observations will be continued in the coming years from these and other observation points.
9. The status of scoters in Finland
Martti Hario, Finnish Game and Fisheries Research Institute
The latest nationwide census of the coastal breeding population of the Velvet Scoter took place in 1997. Following a continuous decrease from the 1960s until the early 1990s, the local populations in the Gulf of Finland seems now to have stabilised at a very low level. Because most monitoring sites in the SW Archipelago Sea lie in the outer zone, the species is poorly covered by regular censuses there. Annual fluctuations in numbers can be large: in the outer zone of the Archipelago Sea the population was estimated at roughly 1,500 pairs in 1992 but only 1,000 pairs two years later. Improved production in the inner zones probably compensates for the losses in the peripheral breeding environment. The total coastal population is estimated to be 13,000 pairs, of which about half occur on the Åland Islands. This total, 6000-7000 pairs, has been questionned by the local authorities in the Åland Islands, who claim the breeding population there to be 6-7 times larger. The inland population is confined to northern Finland, but the species is unevenly distributed over most of the range, being more or less regular only in the small lakes of northernmost Lapland. During the second Bird Atlas survey in 1986-89, the inland population was estimated to number 1,000 pairs. The Åland Islands form an autonomous region in the southwest archipelago, having its own hunting legislation. Formerly, the spring shoot of males involved some 18,000-20,000 Velvet Scoters in the Åland Islands every year. At present, a quota of 6,500 males has been set for the Åland Islands. Throughout the rest of Finland, the species has been totally protected since 1993. In socioeconomic terms, harvesting on the Åland Islands does not represent subsistence harvest, but it still retains considerable cultural importance which makes the spring harvest issue difficult to tackle in the current negotiations between the European Commission and Finland.
The Common Scoter has no coastal breeding population and the inland distribution in northern Finland is basically similar to that of the Velvet Scoter. Both species have suffered a drastic decline in the wooded northern part of the country. Despite this, according to Bird Atlas work in the 1970s and again in the 1980s, no recent change in abundance or occurrence has taken place. Rough estimates suggest between 800 and 1500 breeding Common Scoter pairs in the whole country.
10. Studies of Common Scoter feeding ecology following the 1996 Sea Empress oil spill, South Wales.
Baz Hughes, The Wildfowl & Wetlands Trust, Slimbridge, Gloucester, GL2 7BT, United Kingdom.
When the Sea Empress oil tanker ran aground in February 1996, 8,000 Common Scoter were present in Carmarthen Bay, about half of which were killed by the resulting oil slick. Numbers of Common Scoter in the bay subsequently peaked at 10,000 birds suggesting that at least 15,000 birds used the bay that winter. One year later, counts peaked at only 4,323 birds with few using the usual intertidal feeding areas suggesting they were unsuitable, or at least unprofitable, for foraging Common Scoters. Nearly 2,400 Common Scoter corpses were examined, of which 70% were males (93% second years or older) and 88% adults. About 20% of corpses were not oiled, 32% were partially oiled, and 48% were completely oiled. The first birds recovered from beaches had both high oil and fat scores, but birds deteriorated quickly to emaciation within six days. Most birds had fed on bivalves (96.9%), mainly Egg-shell Razor Pharus legumen (58.1%), an unlikely prey item for Common Scoter due to its large size and rapid burrowing escape response. Dispersed oil may have caused these shellfish to evacuate themselves from the sediment making them readily available to foraging scoters. Trends in diet over time were highly correlated with body condition and oil score. Fatter, heavily oiled birds (those dying shortly after the spill) had fed more on Egg-shell Razors and less on Common Cockles Cardium edule than birds with lower oil and fat scores (those dying later). Multiple regression analysis suggested these trends were related mainly to oil score and body condition rather than date. A lack of detailed data on the availability of benthic invertebrates following the Sea Empress oil spill precluded firm conclusions, but trends in diet may be explained by birds in good body condition being able to feed in deeper water on large Egg-shell Razors. Birds in poor condition were forced to feed in shallower water on smaller, less profitable, Common Cockles. This hypothesis is supported by the likelihood that many birds in poor body condition will have been anaemic, thus reducing their diving ability further.
11. Methods for assessing the effects on birds of wind turbines built in the seas
Johnny Kahlert & Mark Desholm, National Environmental Research Institute, Kalø,
Grenåvej 12, DK 8410 Rønde, Denmark.
In Denmark, it has been proposed to develop large scale offshore windmill parks to increase the contribution made by renewable energy resources to annual domestic electricity generation. At present, five demonstration projects are planned to investigate the technical, economic and environmental feasibility before taking the decision to undertake further development of offshore windmill parks in Denmark.
In the Baltic Sea, one of the windmill parks, comprising ca. 72 x 2.5 MW rated windmills, will be constructed during 2002. A minimum of 300,000 waterbirds, 15,000 raptors and 200,000 passerines pass through the area on autumn migration. If any of the offshore windmill parks are to have an effect on migratory birds, of the five demonstration projects, this park is the site where effects are most likely to be detected and quantified. A radar study is being carried out in the years immediately prior to construction, in order to establish a reference baseline of the spatial pattern of migration routes in and around the proposed construction site and to quantify the future potential response of the birds. The project plans to develop reliable methods to quantify collision frequency risk based on infrared video-recording techniques.
In addition to the intense migration, the area in and round the site of the windmill park is of international importance for mute swan, cormorant and red-breasted merganser. A "before and after" study will be carried out based on aerial survey counts of birds, mapping species and flock distributions using DGPS.
12. European Union Management Plan for the Velvet Scoter Melanitta fusca
J.S. Kirby & M. Linsley, Just Ecology Environmental Consultancy, Head Office – Brookend House, Old Brookend, Berkeley, Gloucestershire, GL13 9SQ, United Kingdom
Work in 1996 aimed at reviewing the conservation status of ‘huntable’ waterbirds, as defined in Annex II of the EC ‘Birds’ Directive, identified Melanitta fusca as one of 26 species with an unfavourable conservation status. The preparation of a community-level management plan was therefore identified as an important means of agreeing action in order to achieve favourable conservation status for this (and the other) species. This paper presents the draft management plan developed for M. fusca, work that was commissioned by the European Commission’s Directorate-General XI ‘Environment’.
The plan developed adheres to the standard format determined by the Commission for these EU management plans. The first part consists of a biological description – a concise synthesis of our understanding of the ecology of the species. This was compiled from published material and also consultations with experts on the species. This description is evaluated in the second part of the plan and the result is a series of management objectives for 2001-2003, with an indication of priorities and discussion of any constraints on the fulfilment of the objectives. Finally, in part 3 of the plan, we outline a series of proposed actions and targets, including targets for policy makers, for site safeguard, species management, international co-operation, and research and monitoring activity.
Here we present the draft EU management plan for M. fusca. We discuss the key gaps in the knowledge of the species, the threats, and the challenges that lie ahead in any programme to improve the conservation status of this species within the EU Member States.
13. Impacts of fast ferries on scoters: a case study
Jesper Kyed Larsen & Bjarke Laubek, Carl Bro as, Nordlandsvej 60, DK-8240 Risskov, Denmark.
We present data on the distributional and behavioural effects of a fast ferry on Common Scoters, with the aim of identifying the character and magnitude of the conflict. Aeroplane surveys were conducted to describe general distribution patterns and, using a semi-experimental setup, to investigate the effects of the ferries on numbers and distribution around the ferry route. Observations were conducted from a travelling ferry, to determine the proportion of flocks taking flight at different distances from the ferry along the route, the escape behaviour and reaction distance in front of the ferry.
Up to 1000 Common Scoters were observed within the study area, the largest concentrations being located at a distance of 1000-2000m from the ferry route. Excluding the ferry from the study site during mornings had no marked effect on numbers and distribution of Common Scoters. When approached by a travelling ferry almost all Common Scoter flocks took flight within 300m of the ferry trajectory, but only a minor proportion at distances greater than 500m. Overall the data suggest that any major disturbance effect of the ferries would be confined to within 1000m distance of the ferry path. The main escape behaviour shown towards an approaching ferry was to take flight. Median flight distance of Common Scoter flocks from the ferry was 325m, with a range of 123-1000m.
We suggest that fast ferries are likely to affect common scoters mainly through disturbance effects, i.e. habitat loss, as they seem unlikely to constitute a major collision risk. The results are compared to data gathered for other sea duck species within the same study, and the focus of future studies on impacts of fast ferries is discussed.
14. Distribution and trends of common and velvet scoter in Norway
Svein-Håkon Lorentsen, NINA, Nature Research, Tungasletta 2, N-7485 Trondheim, Norway
The breeding population of common and velvet scoter in Norway is estimated at 1.000-5.000 and 500-1.500 breeding pairs, respectively. No significant trends have been reported for breeding distribution and numbers, although common scoters have been reported to have disappeared from the western parts of the Hardangervidda National Park, probably due to competition with Minnow (Phoxinus phoxinus). Both species moult in unknown numbers along the coast. Important moulting areas for common scoter exists along the coast of western and central Norway and for velvet scoter in Central Norway. Both species winter along the Norwegian coast, with the largest numbers outside south-western and central Norway. The wintering populations are estimated to 4.000 and 30.000 common and velvet scoters, respectively. An increase in the number of common scoters has been observed at some wintering areas in southern, central and northern Norway and stable populations in others. Amongst velvet scoters declines have been observed in most wintering areas from central Norway and northwards.
15. Winter distribution and numbers of seaducks in Estonian coastal waters in 1995-2000.
Leho Luigujõe, Estonian Ornithological Society, P.O.Box 227, Tartu, 50002, Estonia.
The present report gives an overview of the land-based midwinter counts of seaducks in Estonian coastal waters. The counts have been organized by the Estonian Ornithological Society since 1960. With the increase in the use of aerial survey to monitor waterfowl numbers, Estonian waters were divided into a survey grids (comprising 7 sections, 20 subsections and > 300 count areas). The same grid was used to map distributions from the land-based surveys and in 1995 the whole monitoring program was reorganized. The new scheme is based mainly on fixed routes or observations from fixed points, which together cover over 80% of the ice-free coast. The network of the observers include Estonian Ornithological Society (c.100 observers), local bird clubs (c.40) and professional ornithologists from nature reserves and research institutes (c.10). Birds were recorded up to a distance 1 - 2 km from the coast depending on weather condition and optics.
Fifteen wintering seaduck species were recorded in Estonian coastal waters in 1995-2000, of which 11 species are regular. Goosander and Goldeneye numbers have increased and Steller’s Eider decreased compared with numbers in early 1990s. The most recent estimate of numbers of seaducks wintering in Estonian coastal waters are as follows: Tufted Duck (c.300), Scaup (c.500), Common Eider (c.200), Steller’s Eider (2,000-4,000), Long-tailed Duck (10,000–60,000), Common Scoter (100-600), Velvet Scoter (200-1,000), Goldeneye (10,000–20,000), Smew (100-300), Red-breasted Merganser (300-1,000) and Goosander (3,000-7,000).
16. Non-breeding staging areas for Common and Velvet Scoter in Estonia
Leho Luigujõe & Andres Kuresoo, Estonian Ornithological Society, P.O.Box 227, Tartu, 50002, Estonia.
Large spring concentrations of migrating scoters were first discovered by ornithologists from the Institute of Zoology and Botany during aerial survey in early May 1986. At that time, in the northern part of Livonian Bay, 35,000 Common Scoters were counted (giving an estimated total of ca 100,000 present) with 60,000 Velvet Scoters (total ca. 180,000). However, counts performed in 1993 (a combined survey from ship and aircraft, Durinck et al. 1993) and in 1999 (aerial survey) suggested that the Common Scoter was more the numerous (maximum 130,000) staging species compared to the Velvet Scoter (maximum 70,000).
A large summer staging area for 20,000 Common Scoters was discovered by Finnish birdwatchers in early June 1996 in the western part of the Finnish Gulf (Pettay 1997). Up to 10,000 birds were counted during aerial surveys in July 1999 in same region and at least 2,000 more in shallow waters around Saaremaa Island. In the course of the same survey up to 4,000 and 6,000 Velvet Scoters were counted in these two areas respectively. Occasional land-based late summer observations (e.g. August 1996 and 1998) show that 5,000-12,000 Velvet Scoters stage in the NE part of Livonian Bay. During aerial counts performed in October 1999, only small scattered flocks (in total up to 500) of Velvet Scoters were found.
In the course of ship-based surveys performed by Ornis Consult in February 1992-1993 ca 191,000 and 11,000 Velvet Scoters were estimated wintering in Irbe Strait and northern part of Livonian Bay respectively (Durinck et al. 1994).
17. Numbers, distribution and phenology of scoters along the Polish coast, with special emphasis on the wester Gulf of Gdánsk
Włodzimierz Meissner,Department of Vertebrate Ecology and Zoology, University of Gdánsk, Al. Legionów 9, PL 80-441 Gdánsk, Poland.
The last extensive surveys of scoters in Polish waters were carried out in 1992 and 1993, when some 50,000 Common and 10,000 Velvet Scoters were estimated present, although it was considered that there could be greater numbers further offshore and 60-80,000 Velvet Scoter were counted in January 1999. In the western part of the Bay of Gdánsk, regular counts showed winter peaks of between 200 and 220 Common Scoter and 150-2500 Velvet Scoter, with an apparent decline in numbers of both species since the peak in the late 1980s and early 1990s. While Common Scoter are uniformly distributed along all coasts, the Velvet Scoter is more numerous in eastern Poland. The two species rarely occur in mixed flocks.
18. The distribution and ecology of Velvet and Common Scoter in the Eastern European Russian Tundra
Yuri & Oleg Mineyev, Institute of Biology, Komi Science Centre, Russian Academy of Sciences, Kommunisticheskaya str. 28, 167610, Syktyvkar, Komi Republic, Russia.
The study reports on observations from 1973 until 1999 from the Eastern European tundra (the Nenets Autonomous District of the Archengelsk Oblast). The highly variable nature of the vegetation is a characteristic feature of this tundra area. The vegetation varies between northern (typical) tundra, short and tall dwarf-birch shrub tundra and forest tundra. Velvet and Common Scoters are distributed unevenly within these vegetation zones. Common Scoter nest mainly in tall dwarf-birch shrub tundra while the Velvet Scoter nests in the northern tundra (the Bolshezemelskaya Tundra and the Yugorsky Peninsula), both dwarf-birch shrub tundra types and in the forest tundra. The analysis of the distribution of both scoter species confirms the general reduction in duck numbers that occurred in the Eastern European tundras during the last century.
Common and Velvet Scoters arrive on the tundra during the period 13 May to 10 June. Moult migration occurs between 20 June and 12 July. The seasonal migration of the two species is very distinct in the coastal parts of the Barents Sea and follows the coastline.
During the study period, the density of Common Scoter fluctuated between 0.05 and 1.9 (mean 1.0) individuals km-2 and that of Velvet Scoter between 0.01 and 2.1 (mean 0.5) km-2. The abundance of ducks has a cyclical pattern, with maxima/minima occurring with amplitudes of 2.8, 6 and 12 years. The nesting density of Common and Velvet Scoters was different in various parts of the study area. Common Scoter nesting density varied between 0.01 and 0.48 (mean 0.02) pairs km-2 and Velvet Scoter between 0.01 and 0.1 (mean 0.04) pairs km-2. Both species show common short- and long-term population cycles in nesting density. Peak nesting densities recurred every 3.3 years, 7 and 20 years. It was calculated that between 10.0 and 50.0 % (mean 37,3%) of the potentially breeding Common Scoter population and between 12.6 and 73.3% (mean 34.6%) of the potential Velvet scoter population took part in reproduction. This peak in nesting activity also showed a cyclic pattern of high participation indices with amplitudes of 2.9 and 11 years.
19. Status, distribution and threats to wintering Common Scoters in the Republic of Ireland
Steve Newton & Kendrew Colhoun, BirdWatch Ireland, Ruttledge House, 8 Longford Place, Monkstown, Co. Dublin, Ireland
Common Scoters Melanitta nigra are reasonably common winter visitors to open, shallow coastal waters in the east of Ireland and to the larger enclosed bays of the west coast. Some flocks begin to build up in August and are present through to March or April. The Irish national winter waterbird monitoring scheme, I-WeBS, achieves coverage of most of the known important sites where flocks can be seen from mainland vantage points, though good counts are not achieved every winter. Data from the last six winters show there to be 6 sites that have held 1,000-10,000 Common Scoter with a further 8 sites that regularly hold hundreds. Three of the important sites are in the southwest (Kerry) and 2 are off the east coast in Wexford and Meath. There are probably other flocks on the narrow, shallow banks that run parallel to the east coast approximately 10km offshore adjacent to Dublin and Wicklow that are rarely seen from the mainland and these would require ship- or aerial survey work to locate and enumerate them adequately. The overall Irish wintering population size is perhaps in the range 10,000-20,000. Virtually nothing is known of the wintering ecology of these flocks nor of intra-winter movements between sites and their sensitivity to disturbance. Gathering such information is of high and urgent priority as the Irish Government has recently issued exploratory licences to utility consortia who have announced plans to develop a chain of massive windfarms along the east coast offshore banks.
20. The status of Scoters Melanitta in Sweden.
Leif Nilsson, Department of Ecology, Lund University, Ekologihuset, S-223 62 Lund, Sweden
Both the Common Scoter and the Velvet Scoter breed in Sweden. The only available census data for the inland populations of both species come from the aerial surveys of northern Sweden from the early seventies, which covered the main inland breeding areas for both species. The populations in these areas were estimated to 1800 pairs for Melanitta nigra and 1300 pairs for M. fusca. No recent census data are available for inland Sweden, but some breed in inland areas not covered by the census in the 1970s. The total population of Melanitta nigra in Sweden may be estimated at 2100 pairs (1400 - 2800). For Melanitta fusca the most important populations breed along the Baltic coast, especially in the Stockholm archipelago, Gotland and Västyerbotten. Some older census data are available from the coast. The total Swedish breeding population is estimated to be 18000 pairs (14400 - 21800).
During the winter surveys both species are found as single individuals and in small groups all around the coasts but more regular occurrence of staging and wintering scoters in any numbers is found in Laholmsbukten and Kattegatt on the west coast. Occasional aerial surveys and boat counts in the 1960s and 1970s yielded up to 6000 scoters (of both species) in the area, but up to 3800 Melanitta fusca and 2000 Melanitta nigra have been counted here from the shore. There is an indication of a decrease for the numbers of Melanitta fusca in the area but numbers of Melanitta nigra has increased.
The knowledge of the numbers and distribution of the two species in Swedish Baltic waters is scanty. Aerial surveys and boat counts were undertaken during the late 1960s and early 1970s, but after that only inshore areas have been surveyed. At that time single boat surveys in Hanöbukten and on the south coast of Scania could yield up to a few hundred Melanitta fusca, representing a winter population of up to a few thousand individuals. No recent data are available from these areas but scoters are rarely seen at the counts from the shore in recent years.
Small flocks of especially Melanitta fusca are seen from the shore mainly on Öland and Gotland. For two areas surveyed regularly for index calculations during 1969-80 and from 1987 - 2000, a marked decrease in the number of Scoters was noted, even if numbers at the start were low.
21. Mortality rates from using implantable satellite transmitters in surf and white-winged scoters.
Daniel H. Rosenberg & Michael J. Petrula, Alaska Department of Fish and Game, 333 Raspberry Road, Anchorage, AK 99518, USA.
In 1998, 1999, and 2000 we deployed (surgically implanted) satellite transmitters in surf (Melanitta perspicillata) and white-winged scoters (M. fusca). All birds were captured and released in Prince William Sound, AK. We captured scoters using floating mist nets during late April and early May. In 1998 and 1999 combined, we deployed implantable satellite transmitters in 28 surf scoters and 13 white-winged scoters. Following capture birds were transported to a nearby vessel where surgery was conducted. Birds were released within 5 hours of surgery. If a bird died within 2 weeks of release we considered mortality to be surgically/implant related. We relied on the transmitters internal temperature sensor to indicate the status of the bird (dead or alive). Using this criteria 16 of 28 surf scoters and 5 of 13 white-winged scoters died as a result of the implant. In 2000, we attempted to reduce post-surgical mortality rates by holding birds in captivity at the Alaska SeaLife Center (ASLC) for 12 days following surgery (3 birds were held longer). We implanted 8 surf scoters and 18 white-winged scoters with satellite transmitters at the ASLC. If a bird died while in captivity or within 2 weeks of release we considered the mortality to be related to surgery or captivity. Four of the 8 surf scoters implanted and 3 of 18 white-wing scoters died as a result of surgery/captivity. Unforeseen problems in 2000 associated with the care of both the control and experimental group of captive scoters confounded our attempt to determine the specific cause of post-operative mortality observed in previous years. We suspect the high mortality rates in the first two years of the study resulted from waterproofing problems and hypothermia followed by increased susceptibility to predators, primarily bald eagles (Haliaetus leucocephalus). We appeared to have reduced mortality rates for white-winged scoters but not surf scoters by holding them in captivity.
22. Breeding biology of the Surf Scoter (Melanitta perspicillata).
Jean-Pierre L. Savard and Austin Reed, Canadian Wildlife Service,1141 Route de l’église, P. O. Box 10100, Sainte-Foy, Québec, G1V 4H5.
Until a decade ago, there had been no studies of the breeding biology of the Surf Scoter. The first and to date only comprehensive study was conducted in 1994 and 1995 at Lake Malbaie located about 90 km north of Québec City, Québec. The breeding population was estimated at 47 pairs in 1994 and 65 pairs in 1995. Males spent about only three weeks on the breeding lake and most having left the lake by the third week of June. Clutch size averaged 7.6 ± 0.77 (SD, n = 18) eggs. Incubation lasted around 28 days and was initiated in the second week of June in 1994 and the first week in 1995. Length of stay of females on the breeding lake was related to their reproductive success with successful females staying much longer, well into mid August. Unsuccessful females left about three to four weeks after the males, that is in mid to late July. Females with broods were not territorial and brood amalgamation occurred occasionally. Reproductive success varied between 1994 where a maximum of 80 ducklings were counted and 1995 where 233 ducklings hatched. Most females left their brood prior to fledging. Our brief study indicated great fluctuation in reproductive success between years and a differential departure of birds for their moulting sites according to sex and reproductive success.
23. Wintering feeding ecology and distribution of Common Scoter in Carmarthen Bay
Lucy Smith, Biological Sciences, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
and The benthic ecology of Carmarthen Bay and its relevance to Common Scoter
Andy Woolmer, Biological Sciences, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
Carmarthen Bay is a wide, shallow bay on the south-west coast of Wales. Common Scoter were first reported there in 1932 and since that time, records have shown it to be one of the most important overwintering sites for this species in the United Kingdom. The average winter peak for the site in the mid-1990s was 9000, with maximum counts of 17,650 in December 1994, 18,350 in January 1999 and 21,345 in January 2000. In February 1996, the Sea Empress oil tanker grounded off West Wales, spilling 72,000 tonnes of crude oil. The spillage extended into Carmarthen Bay leaving 4,700 Common Scoter oiled in local bays. As a result of this disaster, the Countryside Council for Wales funded two Ph.D. Studentships to investigate the benthos and the Common Scoter populations of the Bay. The benthic investigations have produced a detailed community map of the benthos for the entire Bay and a time series (over 2 years for specific areas. The scoter study has produced distribution maps for 82 days over the past two winters. By combining these data sets, it will be possible to investigate the relationship between Common Scoter distribution within the Bay and sediment type, benthic community type, water depth and weather factors.
24. Common and Velvet Scoter numbers in Latvia in the course of the year
Antra Stipniece, Institute of Biology, LU, Miera 3, Salaspils LV-2169, Latvia.
& Agris Celmins, PO Box 1603, Riga, LV-1050, Latvia.
This overview summarises the available recent information on the two Scoter species in Latvia. The synthesis of spring migration observations is based upon counts from one coastal observation point (Pape) during 1988-1990 inclusive and ship surveys in late March 2000. The summer status is based upon a literature review of occasional breeding records and extensive moult migration observations, together with an aerial survey of the coastal area (out to the 30 m depth contour) in August 1999. Some autumn migration observations from Pape in November 1999 will be presented. The winter status of scoters comes from Wetlands International IWC mid-January counts from the coast and 4 ship surveys in late February 1992, 1993, 1998 and 2000. Possible changes in the numbers and distribution of scoters wintering in the Gulf of Riga are discussed.
25. The Common Scoter in Ireland – breeding numbers, production estimates and diurnal activity budgets.
David Tierney, Department of Zoology, National University of Ireland, Galway, Ireland.
The Common Scoter is an endangered breeding bird in Ireland with approximately 75 breeding pairs spread over four lakes in the west of Ireland. Population trends and rates of productivity are being evaluated. The results of diurnal activity budgets for both adults and young will be reported.
26. The habitat and feeding ecology of Velvet Scoters wintering in Lithuanian coastal waters
Ramunas Zydelis, Institute of Ecology, Akademijos 2, LT-2600 Vilnius, Lithuania
Velvet Scoters wintering along the Lithuanian coast of the Baltic Sea were studied in relation to their marine environment. The species demonstrated a significant tendency to occupy marine areas with sandy bottom substrates at depths between 2 and 30 m.. The diet of Velvet Scoters was dominated by benthic organisms common in the soft bottom biotopes: namely the infaunal bivalves Mya arenaria and Macoma baltica, crustacean Mesidothea entomon and polychaete Nereis diversicolor. Estimates suggest that the high densities of Velvet Scoters exploiting these relatively poor benthic biotopes play important role as top predators in their wintering area.
27. Some aspects of the diet and habitat use of Common Scoters wintering off the Lithuanian coast
Ramunas Zydelis, Institute of Ecology, Akademijos 2, LT-2600 Vilnius, Lithuania
Common Scoters, wintering in Lithuanian inshore waters were observed using a variety of marine benthic biotopes. The species show no significant selection for any particular marine habitat. Fifteen drowned Common Scoter corpses were obtained from fisherman for diet analysis in February – April 2000. Four invertebrate species dominated the diet: the bivalves Macoma baltica and Mya arenaria appeared to be the most important prey species, but the Polychaete Nereis diversicolor was found in all analysed birds. A few birds contained the crustacean Mesidothea entomon.