| 1. |
- Milberg, Per, 1959-, et al.
(författare)
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Submerged vegetation and the variation in the autumn waterfowl community at Lake Tσkern, southern Sweden
- 2002
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Ingår i: Ornis Fennica. - 0030-5685. ; 79:2, s. 72-81
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Tidskriftsartikel (refereegranskat)abstract
- We analysed data from 25 years of standardised mid-September counts of waterfowl at eutropic Lake Tσkern, southern Sweden. For eight species, counts were compared with a national index constructed from similar counts at numerous lakes and coastal sites. For Crested Grebes and Mute Swans there was a correlation between counts at Lake Tσkern and the national index, suggesting that they simultaneously vary in number over a large geographic area. Indirect gradient analysis (PCA) revealed a strong temporal trend in the data, which was covaried out in a partial PCA to expose residual patterns. This ordination separated Pochards and Tufted Ducks at one end of the first axis from Cormorants and Goosanders at the other. A direct gradient analysis, with biomass of submerged macrophytes (recorded for 14 of the 25 years) as the sole environmental variable, showed that bird species composition varied significantly with plant biomass. The piscivores, Cormorants and Goosanders, were abundant in years with small amounts of plant biomass, while several species were most abundant in years with large amounts. Our analyses suggest that the abundance of submerged macrophytes is an important determinant of the bird community composition in eutrophic lakes.
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| 2. |
- Skov, Henrik, et al.
(författare)
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Waterbird Populations and Pressures in the Baltic Sea
- 2011
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Bok (refereegranskat)abstract
- This report outlines the results of the internationally coordinated census of wintering waterbirds in the Baltic Sea 2007-2009 undertaken under the SOWBAS project (Status of wintering Waterbird populations in the Baltic Sea). The estimated total number of wintering waterbirds was 4.41 million compared to 7.44 million during the last co-ordinated census 1992-1993. Despite the general declines stable or increasing populations of herbivorous species were recorded. While benthic carnivores with a coastal distribution have either shown moderate declines, stable or increasing populations seaducks with an offshore distribution have declined seriously.
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| 3. |
- Nilsson, Leif, et al.
(författare)
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Changes in numbers and distribution of breeding waterfowl in the Swedish mountain chain between 1972–1975 and 2009
- 2012
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Ingår i: Ornis Svecica. - 1102-6812. ; 22:3-4, s. 107-126
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Tidskriftsartikel (refereegranskat)abstract
- During 1972–1975, the breeding waterfowl populations of the northern parts of Fennoscandia (south to 65° N in Sweden) were surveyed for the first time. In 2009, a new survey was undertaken in the Swedish part of the mountain chain. Censuses were performed from the air in transects of 5×5 km squares and in special areas. The distribution of the different species was largely similar between the two periods but there were a number of differences on the regional level. Most species had more or less the same population sizes but there were some variation in the different parts of the mountains. Three species showed clear increases between the periods. Cygnus cygnus had the same increase in the mountain chain as in the rest of the country. Melanitta nigra was about four times as common in 2009 compared to the 1970s and Mergus merganser also had higher counts in 2009. Melanitta fusca decreased
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| 4. |
- Andersson, Åke, et al.
(författare)
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Migration Patterns of Nordic Greylag Geese Anser anser.
- 2001
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Ingår i: Ornis Svecica. - 1102-6812. ; 11, s. 19-58
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Tidskriftsartikel (refereegranskat)abstract
- Migration patterns of Nordic Greylag Geese Anser anserwere studied by means of neck-collaring. A total of 4173birds (738 breeders, 1999 goslings and 1436 moulters;most moulters subsequently identified as belonging to aspecified breeding population) was marked throughoutNorway, Sweden, Denmark and Finland during 1984–1994. This report is based on observations made up to 30June 1995. In general, Norwegian Greylag Geese left theirbreeding areas rapidly for staging areas in Denmark and/or the Netherlands during the period late August – earlySeptember, but the most northerly breeding populationsmigrated south much later and not so rapidly. After a longrefuelling period most Norwegian Greylags left theNetherlands for wintering areas in Spain during November.The Guadalquivir Marismas in the south-western part ofthe country was the main wintering area, but sites in theDuero Basin in the north-central part gained importancethroughout the study period. Normally, the geese left Spainin February, for a long stop-over in the Netherlands.Breeders returned to Vega in Norway in April, but to Tromsand Finnmark not until May. Most Greylags from Scaniaand Denmark, all belonging to the West Baltic population,remained in the breeding area until October, merging intolarger and larger flocks, together with returning moultersand birds from more northern breeding grounds. Themajority made only a short stop-over in the Netherlandsen-route to their main winter quarter, the GuadalquivirMarismas, Spain. An increasing proportion wintered in theDutch Delta. In general, West Baltic Greylags left theirwinter quarters during the first two weeks of February andmigrated rapidly to the breeding grounds. Largely,Norwegian and West Baltic Greylags used different stagingareas in the Netherlands and non-overlapping feedingareas in Spain. Outside the Atlantic flyway there is a fewre-sightings from England of Norwegian and Swedishbirds as well as one re-sighting each from Scotland andHungary of a Swedish Greylag. Finnish reylags werefound along both the Atlantic flyway, down to theGuadalquivir Marismas, and the Continental flyway, downto Tunisia and Algeria. Winter quarters of the two studiednaturalised populations were situated apart from the mainones; Greylags from the Oslo area wintered in theNetherlands and the majority from Södermanland at Lacdu Der, east of Paris.
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| 5. |
- Dalby, Lars, et al.
(författare)
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The status of the Nordic populations of the Mallard (Anas platyrhynchos) in a changing world
- 2013
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Ingår i: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 90:1, s. 2-15
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Tidskriftsartikel (refereegranskat)abstract
- Dabbling ducks (Anas spp.) are important migratory quarry species, protected as a shared resource under international legislation. However, there is a lack of sufficient high-quality data on vital demographic rates and long-term trends in numbers to judge the conservation status of many duck populations at the flyway level. In response to reported declines in the North-West European flyway population of the Mallard, we compiled available data on this species in the Nordic countries up to 2010. Generally, national breeding numbers showed increasing trends, wintering abundance showed variable trends, and productivity measures indicated stable or increasing trends. Major knowledge gaps were identified, namely the size of hunting bags, the influence of the released Mallards and the role of short-stopping in explaining changing patterns of wintering abundance across the North-West European flyway. Numerically the Nordic breeding population appears in "good condition", and the wintering numbers have been either stable or increasing in the last two decades. The annual number of releases needs to be determined in order to judge the sustainability of the current levels of exploitation. Overall, none of the indicators showed alarming signs for the Mallard population in the Nordic countries when considered in isolation. However, the widespread decline in wintering numbers elsewhere across North-western Europe requires urgent pan-European action.
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| 6. |
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| 7. |
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| 8. |
- Nilsson, Leif, et al.
(författare)
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Change of mate in a Greylag Goose Anser anser population effects of timing on reproductive success
- 2001
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Ingår i: Wildfowl. - 0954-6324. ; , s. 31-40
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Tidskriftsartikel (refereegranskat)abstract
- The population of the West Baltic Greylag Goose Anser anser is migratory,breeding in southwest Scania, southernmost Sweden and wintering in theGuadalquivir Marismas, southwest Spain, or in the Dutch Delta. This populationhas been the subject of a long-term study o f a sample o f neck cottaredindividuals, and observations o f marked individuals were used to assessrates of mate fid e lity in this supposedly long-term monogamous species.The annual divorce rate during the years 1985-2000 was 10.5% [n-415], with29.7% of alt pairs ending in a divorce [n=158¡. A fte r divorce or death of thepartner, birds re-paired assortatively with individuals from th e ir own breedingarea, using the same wintering area. New p a ir bonds formed on thebreeding area, during one of three periods; ju s t a fte r re tu rn in spring, ju s ta fte r m o u lt and ju s t before departure in autumn. Divorce o r p a rtn e r deathduring the period 15 October - 28 February, when breeders were away fromthe breeding grounds, resulted in a significantly tower reproductive successduring the following breeding season, compared to mate losses during theperiod 1 June - 14 October.
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| 9. |
- Nilsson, Leif
(författare)
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Changes in abundance and breeding output of Greylag Geese Anser anser breeding in southern Sweden
- 2018
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Ingår i: Wildfowl. - 0954-6324. ; 68, s. 44-69
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Tidskriftsartikel (refereegranskat)abstract
- Neck-banded Greylag Geese Anser anser from a population breeding in southwest Scania, southern Sweden, were studied to assess changes in the breeding population and breeding performance during 1984–2013. The population increased ten-fold during this period, only to decrease again in the later years of the study. Greylag Geese arrived on the breeding grounds about 3–4 weeks earlier by 2007–2009 compared to the 1980s, probably an effect of wintering further north closer to the breeding areas in more recent years. Mean hatch date did not advance significantly over the same period. The proportion of breeding Greylag Geese that produced a brood of small young decreased during the study. On the other hand, the mean brood size at hatching for those succeeding in producing a brood, and the survival of young to fledging amongst marked families, showed no significant trends.
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| 10. |
- Nilsson, Leif, et al.
(författare)
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Changes in field choice among staging and wintering geese in southwestern Scania, South Sweden.
- 2000
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Ingår i: Ornis Svecica. - 1102-6812. ; 10:3-4, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Field choice of staging and wintering geese were regularlynoted during the International Goose Counts in south-westScania, South Sweden, since the start in 1977/78. Markedchanges in the selection of field types was noted during theautumn counts. When the counts started sugar beet fieldswere important for Anser fabalis during late autumn,whereas Anser albifrons, Branta canadensis and the fewstaging Branta leucopsis mainly used autumn-sown cerealsand grassland, and the few observed Anser anser fed onstubbles. During the study period all species changed tofeed on sugar beet remains during autumn, and this was thepreferred food for all species in recent years; B. canadensisand A. anser changed around 1988–1990, whereas the twosmaller species A. albifronsand B. leucopsis changed later.In winter, most remaining geese used
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