| 1. |
- Beekman, Jan, et al.
(författare)
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Long-term population trends and shifts in distribution of Bewick's swans cygnus columbianus bewickii wintering in northwest Europe
- 2020
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Ingår i: Wildfowl. - 0954-6324. ; :69, s. 73-102
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Tidskriftsartikel (refereegranskat)abstract
- Coordinated international censuses of the Northwest European Bewick's Swan Cygnus columbianus bewickii population have been undertaken across the swans' wintering range at c. 5-year intervals since 1984. During the early years of the study, numbers increased steadily to a peak of 29,780 individuals in January 1995, but then declined by 39.4% to 18,057 swans counted in January 2010 before showing a partial recovery to 20,149 recorded in January 2015. Changes in distribution across the wintering range were also recorded; a higher proportion of the population now remains in more easterly countries (notably Germany) in mid-winter, whilst only a handful of birds migrated to Ireland (at the western edge of the range) during the 2000s compared to >1,000 wintering there at the start of the study. Variation between censuses in the proportion of swans recorded in different parts of the range were attributable to weather conditions, with more swans wintering further north in warmer years. The overall percentage of cygnets recorded in each of the census years ranged from 9.6% in 2010 to 13.2% in 2005, with no obvious consistency over time in the distribution of cygnets across the wintering range. There were however changes between 1990 and 2015 in the swans' use of feeding habitats, with a decline in the proportion of birds on pasture and a corresponding increase in those on arable land. Decreases in the total population size and changes in distribution in the 21st century have implications for the designation and resultant protection of sites of international importance for the species.
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| 2. |
- Champagnon, Jocelyn, et al.
(författare)
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Consequences of massive bird releases for hunting purposes : mallard Anas platyrhynchos in the Camargue, Southern France
- 2009
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special issue 2, s. 184-191
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Tidskriftsartikel (refereegranskat)abstract
- The release of captive-reared fish and game animals into the wild is a common management practice in Europe and North America. In Europe, millions of reared birds are released each year yet the consequences of these release programmes have received little attention. This paper describes the massive introduction of Mallard Anas platyrhynchos, a native migrant species released into the wild to increase the size of hunted populations. It provides the rationale for current and forthcoming experiments aimed at determining the effects of the augmentation of Mallard stocks on wild population genotype and survival rates.
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| 3. |
- Champagnon, Jocelyn, et al.
(författare)
-
Consequences of massive bird releases for hunting purposes : mallard Anas platyrhynchos in the Camargue, Southern France
- 2009
-
Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special issue 2, s. 184-191
-
Tidskriftsartikel (refereegranskat)abstract
- The release of captive-reared fish and game animals into the wild is a common management practice in Europe and North America. In Europe, millions of reared birds are released each year yet the consequences of these release programmes have received little attention. This paper describes the massive introduction of Mallard Anas platyrhynchos, a native migrant species released into the wild to increase the size of hunted populations. It provides the rationale for current and forthcoming experiments aimed at determining the effects of the augmentation of Mallard stocks on wild population genotype and survival rates.
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| 4. |
- Eichholz, Michael W., et al.
(författare)
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Nest site selection by Holarctic waterfowl : a multi-level review
- 2014
-
Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 86-130
-
Tidskriftsartikel (refereegranskat)abstract
- Because of birds’ mobility, behaviour and many species’ migratory nature, they select repeatedly and spatially among habitats and have been central figures in studies of avian breeding habitat selection during the 20th and 21st centuries. The scientific literature on habitat use by breeding waterfowl has origins dating back to the writings of Charles Darwin in The Voyage of the Beagle, wherein he described the distribution and habitat differences of two species of geese on the Falkland Islands. Since that time, waterfowl ecologists have gone from descriptive studies of nest site characteristics used for planning waterfowl conservation and management to comparing nest site use in relation to potential habitat availability and determining selection for a wide array of ecological correlates. Waterfowl ecologists most recently have been investigating the adaptive significance of nest site selection by associating the latter with individual fitness and demographic measurements to assess the birds’ adaptability under environmental conditions at multiple scales of selection. While little direct assessment of 1st and 2nd order nest site selection has occurred (sensu Johnson 1980), available information is most consistent with the hypothesis that selection at these scales is driven by food availability. At the 3rd and 4th order of selection, data are consistent with hypotheses that both food availability and predator avoidance drive nest site selection, depending on the species and type of nesting aggregation. We also identify understudied areas of nest site selection important for the conservation and management of waterfowl and suggest that the large-scale influence of current anthropogenic and natural effects on the environment indicates that greater emphasis should be directed toward understanding waterfowl nest site selection at the 1st and 2nd orders of selection and how nesting habitat selection interfaces with community ecology of sympatric breeding waterfowl. Moreover, because habitat selection of prefledging waterfowl is inherently linked to breeding habitat selection, we suggest an updated review of brood habitat selection should ensue from our synthesis here.
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| 5. |
- Eichholz, Michael W., et al.
(författare)
-
Nest site selection by Holarctic waterfowl : a multi-level review
- 2014
-
Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special Issue 4, s. 86-130
-
Tidskriftsartikel (refereegranskat)abstract
- Because of birds’ mobility, behaviour and many species’ migratory nature, they select repeatedly and spatially among habitats and have been central figures in studies of avian breeding habitat selection during the 20th and 21st centuries. The scientific literature on habitat use by breeding waterfowl has origins dating back to the writings of Charles Darwin in The Voyage of the Beagle, wherein he described the distribution and habitat differences of two species of geese on the Falkland Islands. Since that time, waterfowl ecologists have gone from descriptive studies of nest site characteristics used for planning waterfowl conservation and management to comparing nest site use in relation to potential habitat availability and determining selection for a wide array of ecological correlates. Waterfowl ecologists most recently have been investigating the adaptive significance of nest site selection by associating the latter with individual fitness and demographic measurements to assess the birds’ adaptability under environmental conditions at multiple scales of selection. While little direct assessment of 1st and 2nd order nest site selection has occurred (sensu Johnson 1980), available information is most consistent with the hypothesis that selection at these scales is driven by food availability. At the 3rd and 4th order of selection, data are consistent with hypotheses that both food availability and predator avoidance drive nest site selection, depending on the species and type of nesting aggregation. We also identify understudied areas of nest site selection important for the conservation and management of waterfowl and suggest that the large-scale influence of current anthropogenic and natural effects on the environment indicates that greater emphasis should be directed toward understanding waterfowl nest site selection at the 1st and 2nd orders of selection and how nesting habitat selection interfaces with community ecology of sympatric breeding waterfowl. Moreover, because habitat selection of prefledging waterfowl is inherently linked to breeding habitat selection, we suggest an updated review of brood habitat selection should ensue from our synthesis here.
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| 6. |
- Elmberg, Johan, 1960-
(författare)
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Are dabbling ducks major players or merely noise in freshwater ecosystems? : a European perspective, with references to population limitation and density dependence
- 2009
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special issue 2, s. 9-23
-
Tidskriftsartikel (refereegranskat)abstract
- Waterfowl ecologists consider ducks important players in patterns and processes of freshwater ecosystems. Limnologists and fish biologists, on the other hand, historically have “a bottom-up” view of the same systems, often regarding waterbirds as “background noise” compared to other biotic influences. Evidence for and against these largely opposing views is reviewed, focussing on European dabbling duck studies. In oligo- and mesotrophic wetlands at low breeding density, their role is likely to be overshadowed by biotic interactions between fish, invertebrates and plants. Conversely, many other freshwater systems may be affected by dabbling ducks in various ways, acting as dispersers of invertebrates and plants, as predators, and as eutrophicators. It is concluded that dabbling ducks affect freshwater systems more profoundly than has hitherto been acknowledged. In their turn, freshwater ecosystems affect the ducks’ population ecology. In a less comprehensive treatment, the evidence for the major paradigms addressing population limitation in dabbling ducks is discussed briefly from a European perspective. It is concluded that top-down (predation) as well as bottom-up (food limitation) processes may both affect population size, but evidence for either is correlative, necessitating more experimental studies based on explicit predictions from pattern-oriented studies. In a discussion of the prospects for adopting a more adaptive management approach for European dabbling ducks, it is argued that a lack of information about annual variation in recruitment and harvest rates are major obstacles to understanding population change and for adopting a more adaptive management. A compilation of European studies about density dependence in Mallard Anas platyrhynchos indicates that population regulation may be a common phenomenon in this species, with possible important ramifications for research as well as management programmes.
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| 7. |
- Elmberg, Johan
(författare)
-
Are dabbling ducks major players or merely noise in freshwater ecosystems? : a European perspective, with references to population limitation and density dependence
- 2009
-
Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special issue 2, s. 9-23
-
Tidskriftsartikel (refereegranskat)abstract
- Waterfowl ecologists consider ducks important players in patterns and processes of freshwater ecosystems. Limnologists and fish biologists, on the other hand, historically have “a bottom-up” view of the same systems, often regarding waterbirds as “background noise” compared to other biotic influences. Evidence for and against these largely opposing views is reviewed, focussing on European dabbling duck studies. In oligo- and mesotrophic wetlands at low breeding density, their role is likely to be overshadowed by biotic interactions between fish, invertebrates and plants. Conversely, many other freshwater systems may be affected by dabbling ducks in various ways, acting as dispersers of invertebrates and plants, as predators, and as eutrophicators. It is concluded that dabbling ducks affect freshwater systems more profoundly than has hitherto been acknowledged. In their turn, freshwater ecosystems affect the ducks’ population ecology. In a less comprehensive treatment, the evidence for the major paradigms addressing population limitation in dabbling ducks is discussed briefly from a European perspective. It is concluded that top-down (predation) as well as bottom-up (food limitation) processes may both affect population size, but evidence for either is correlative, necessitating more experimental studies based on explicit predictions from pattern-oriented studies. In a discussion of the prospects for adopting a more adaptive management approach for European dabbling ducks, it is argued that a lack of information about annual variation in recruitment and harvest rates are major obstacles to understanding population change and for adopting a more adaptive management. A compilation of European studies about density dependence in Mallard Anas platyrhynchos indicates that population regulation may be a common phenomenon in this species, with possible important ramifications for research as well as management programmes.
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| 8. |
- Fox, Anthony D., et al.
(författare)
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Recent changes in the abundance of Common Pochard Aythya ferina breeding in Europe
- 2016
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Ingår i: Wildfowl. - 0954-6324. ; 66, s. 22-40
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Forskningsöversikt (refereegranskat)abstract
- National accounts suggest that the Common Pochard Aythya ferina was an uncommon breeding bird throughout western Europe before 1850. Extensions to the breeding range in the late 19th century were potentially aided by the rapid development of managed fish-ponds in eastern Europe, which provided suitable novel habitat at that time. Expansion into western Europe followed in subsequent decades. Wetland and waterbody eutrophication throughout Europe, which likely provided food and cover for the birds, may have accelerated the rapid expansion from the 1950s until the early 1980s. Widespread declines in the last 30 years, especially in eastern Europe, where breeding numbers are highest, are possibly linked to intensification and/or abandonment of freshwater fish farming and changes in water quality. Studies show that Pochard gain fitness benefits from nesting in Black-headed Gull Chroicocephalus ridibundus colonies and hence has been affected by major losses of European gull colonies in the last 30 years. The spread of alien fish species such as the Carp Cyprinus carpio, which compete with Pochard for food resources, is a problem in the Mediterranean region. Changing predation pressures (in some cases linked to invasive alien mammals) are also implicated in some areas. Relatively modest numbers breeding in the UK, France and the Netherlands have remained stable or increased over the same recent span of years, confirming that different factors currently affect Pochard breeding abundance throughout its range. We urgently need better information relating to key factors affecting Pochard breeding success and abundance, which is currently showing an unfavourable conservation status throughout much of Europe.
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| 9. |
- Kaminski, Richard M., et al.
(författare)
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An introduction to habitat use and selection by waterfowl in the northern hemisphere
- 2014
-
Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 9-16
-
Tidskriftsartikel (refereegranskat)abstract
- This introductory article aims to provide a theoretical framework to the topics of habitat use and selection by waterfowl (i.e. family Anatidae) in the northern hemisphere during the four stages of their annual cycle: autumn migration and winter, spring migration and pre-breeding, nesting and brood rearing, and postbreeding and moulting. Papers addressing each of these seasonal sectors of the annual cycle, which follow this introduction, were presented at the 6th North American Duck Symposium, “Ecology and Conservation of North American Waterfowl” in Memphis, Tennessee in January 2013. Here, we consider the theory and selected empirical evidence relevant to waterfowl habitat and resource use and selection that may affect individual survival and fitness of waterfowl in Nearctic and Palearctic ecozones. Additionally, where possible, a comparative taxonomic approach is attempted in the following papers to identify and generalise patterns in habitat and resource use and selection across waterfowl taxa that may influence biological outcomes for individuals, populations and species through space and time. Each of the subsequent papers use accumulated science-based information to recommend future opportunities and strategies for research and for habitat and population conservation. Collectively, our goals in synthesising information on waterfowl are to help sustain harvestable populations of waterfowl and to protect rare species amid worldwide changes in climate, landscape, economics, socio-politics and growth of human populations.
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| 10. |
- Kaminski, Richard M., et al.
(författare)
-
An introduction to habitat use and selection by waterfowl in the northern hemisphere
- 2014
-
Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special Issue 4, s. 9-16
-
Tidskriftsartikel (refereegranskat)abstract
- This introductory article aims to provide a theoretical framework to the topics of habitat use and selection by waterfowl (i.e. family Anatidae) in the northern hemisphere during the four stages of their annual cycle: autumn migration and winter, spring migration and pre-breeding, nesting and brood rearing, and postbreeding and moulting. Papers addressing each of these seasonal sectors of the annual cycle, which follow this introduction, were presented at the 6th North American Duck Symposium, “Ecology and Conservation of North American Waterfowl” in Memphis, Tennessee in January 2013. Here, we consider the theory and selected empirical evidence relevant to waterfowl habitat and resource use and selection that may affect individual survival and fitness of waterfowl in Nearctic and Palearctic ecozones. Additionally, where possible, a comparative taxonomic approach is attempted in the following papers to identify and generalise patterns in habitat and resource use and selection across waterfowl taxa that may influence biological outcomes for individuals, populations and species through space and time. Each of the subsequent papers use accumulated science-based information to recommend future opportunities and strategies for research and for habitat and population conservation. Collectively, our goals in synthesising information on waterfowl are to help sustain harvestable populations of waterfowl and to protect rare species amid worldwide changes in climate, landscape, economics, socio-politics and growth of human populations.
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| 11. |
- Koons, D. N., et al.
(författare)
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Drivers of waterfowl population dynamics : from teal to swans
- 2014
-
Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 169-191
-
Tidskriftsartikel (refereegranskat)abstract
- Waterfowl are among the best studied and most extensively monitored species in the world. Given their global importance for sport and subsistence hunting, viewing and ecosystem functioning, great effort has been devoted since the middle part of the 20th century to understanding both the environmental and demographic mechanisms that influence waterfowl population and community dynamics. Here we use comparative approaches to summarise and contrast our understanding of waterfowl population dynamics across species as short-lived as the teal Anas discors and A. crecca to those such as the swans Cygnus sp. which have long life-spans. Specifically, we focuson population responses to vital rate perturbations across life history strategies, discuss bottom-up and top-down responses of waterfowl populations to global change, and summarise our current understanding of density dependence across waterfowl species. We close by identifying research needs and highlight ways to overcome the challenges of sustainably managing waterfowl populations in the 21st century.
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| 12. |
- Koons, D. N., et al.
(författare)
-
Drivers of waterfowl population dynamics : from teal to swans
- 2014
-
Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special Issue 4, s. 169-191
-
Tidskriftsartikel (refereegranskat)abstract
- Waterfowl are among the best studied and most extensively monitored species in the world. Given their global importance for sport and subsistence hunting, viewing and ecosystem functioning, great effort has been devoted since the middle part of the 20th century to understanding both the environmental and demographic mechanisms that influence waterfowl population and community dynamics. Here we use comparative approaches to summarise and contrast our understanding of waterfowl population dynamics across species as short-lived as the teal Anas discors and A. crecca to those such as the swans Cygnus sp. which have long life-spans. Specifically, we focuson population responses to vital rate perturbations across life history strategies, discuss bottom-up and top-down responses of waterfowl populations to global change, and summarise our current understanding of density dependence across waterfowl species. We close by identifying research needs and highlight ways to overcome the challenges of sustainably managing waterfowl populations in the 21st century.
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| 13. |
- Laubek, Bjarke, et al.
(författare)
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Whooper swan cygnus cygnus January population censuses for northwest mainland Europe, 1995-2015
- 2020
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Ingår i: Wildfowl. - 0954-6324. ; :69, s. 103-122
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Tidskriftsartikel (refereegranskat)abstract
- Internationally coordinated censuses of Whooper Swans Cygnus cygnus across continental northwest Europe were undertaken in mid-winter 1995, 2000, 2005, 2010 and 2015. The estimate of 138,500 birds in 2015, the highest to date, represented a more than doubling of the population size (at an annual increase of 4.1%) since the first census total of 59,000 swans in 1995. The largest increase was in Denmark, where numbers almost trebled from 21,740 in 1995 to 62,620 in 2015. More than 97% of all swans were counted in just six countries. The percentage of total numbers increased significantly between 1995 and 2015 in Denmark (from 36.5% to 45.2%) and Germany (26.0% to 34.7%), but declined significantly in Sweden (14.2% to 8.4%), Norway (13.1% to 3.6%), Poland (6.2% to 4.0%) and the Netherlands (2.4% to 1.7%). The counts show an increasing discrepancy between national trends in abundance for Whooper Swans in Sweden and especially in Denmark in comparison with results obtained only from mid-winter International Waterbird Count (IWC) site coverage. This demonstrates the increasing tendency for Whooper Swans to winter in areas away from traditionally counted IWC sites and confirms the continued need for a regular cycle of coordinated dedicated swan counts to anchor population trends generated from other data sources.
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| 14. |
- 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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| 15. |
- 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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| 16. |
- Nilsson, Leif, et al.
(författare)
-
Changes in numbers of staging and wintering geese in Sweden : 1977/78-2019/20
- 2020
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Ingår i: Wildfowl. - 0954-6324. ; :70, s. 107-126
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Tidskriftsartikel (refereegranskat)abstract
- Regular goose counts made throughout Sweden since 1977/78 show that the total numbers staging and wintering in the country have increased markedly over the decades. October totals were of 51,000 geese in 1977, rising to c. 600,000 in 2018, during which time January totals also increased from 31,000 to 252,000 birds. The greatest change recorded was for the Greylag Goose Anser anser, numbers of which rose from 20,000 to > 250,000 individuals over a 35-year period. Changes in migration and wintering habits have also been recorded, with mid-winter (January) Greylag Goose numbers now amounting to 20-33% of the September totals in recent years, illustrating increases in the proportion of the population now wintering in the country. Moreover, large numbers of Barnacle Geese Branta leucopsis have started to stage and over-winter in Sweden, and are now becoming the commonest species, with 365,000 recorded in autumn 2019.
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| 17. |
- Nilsson, Leif, et al.
(författare)
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Factors affecting the local distribution of the Long-tailed Duck Clangula hyemalis in Baltic offshore waters
- 2016
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Ingår i: Wildfowl. - 0954-6324. ; 66, s. 142-158
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Tidskriftsartikel (refereegranskat)abstract
- The Long-tailed Duck Clangula hyemalis is the main offshore wintering seaduckspecies in the Baltic region, although numbers have declined steeply since the early 1990s. The reasons for the decline are not well understood and information about habitat choice is scarce. Blue Mussels Mytilus edulis are the main food source for Longtailed Ducks in the southern Baltic Sea and here we have used both modelled and measured raw data on Mytilus abundances, patchiness and various bathymetric parameters to study Long-tailed Duck habitat preferences. Long-tailed Ducks were most abundant at depths of 10–30 m and in areas of high Mytilus densities. Patchiness of the resource was also very influential, especially when overall Mytilus densities were low. Bird abundance was intermediate to high in areas of low patchiness and lowwhere Mytilus patchiness was high. This suggests that the birds seek areas thatoptimise their feeding efficiency.
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| 18. |
- Nilsson, Leif, et al.
(författare)
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Field choice in spring and breeding performance of Greylag Geese Anser anser in Southern Sweden.
- 2002
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Ingår i: Wildfowl. - 0954-6324. ; 53, s. 7-25
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Tidskriftsartikel (refereegranskat)abstract
- Selection and exploitation of feeding areas by pre-breeding and nonbreeding Greylag Geese A nser anser, as we ll as by families, was studied in a breeding area consisting of four lakes in Scania, southernmost Sweden, in the years 1997-2000. Total production of young in each lake as we ll as the breeding performance of neck collared individuals was established annually, 1985-2000. This breeding population increased on average 15.3% p e ra n n um, from 93 pairs in 1985 to 910 pairs in 2001. The two main field types used by pre-breeding pairs, males of incubating females and non-breeders in flocks were win te r wheat and grassland, often switching from the fo rme r to the latter in mid-season. Almost all feeding during brood- rearing took place on pastures grazed by livestock or on a golf-course. Generally in spring, the rates of exploitation were below 300-400 goose days ha"1, but rates of >1,000 goose days ha' 1 were noted for one cereal field and two grassland areas. The rates of exploitation by families varied markedly among brood-rearing areas as we ll as years, being highest all through the study period on a grazed pasture, where it ranged 800-1,350 goose days ha'1. Including the utilisation by non-breeders, the annual exploitation of this pasture ranged from 1,400 to 2,500 goose days h a 1. At the only lake without grazing by livestock (since the mid-1990s), significantly fewer goslings survived to fledging than at the other lakes (45% vs 70%). Indications of density-dependent effects on the productivity of sma ll young were noted at one of the lakes (Klosterviken) but not at another (Yddingen). Most likely, the lack of any density dependent effect, in spite of the very marked increase in the breeding population during the study period at Yddingen, is the result of access to highly fertilized grass on a golf course.
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| 19. |
- Nilsson, Leif, et al.
(författare)
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France as a staging and wintering area for Greylag Geese Anser anser.
- 2013
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Ingår i: Wildfowl. - 0954-6324. ; 63, s. 24-39
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Tidskriftsartikel (refereegranskat)abstract
- France is traditionally a staging area for Greylag Geese Anser anser migrating fromnorthwest Europe to wintering sites in Spain, though increasing numbers havewintered in France over the last three decades. This paper considers sightings withinFrance of neck-banded individuals marked elsewhere in Europe since the 1980s, todetermine the origin of Greylag Geese staging and now wintering in the country. The geese included in this study were all caught in summer during the annual moult, either as family groups or in non-breeding flocks. Most sightings of neck-banded geese were from western France, and most birds identified were from breeding areas in the Nordic countries or to a lesser extent in the Netherlands. The Lac du Der area in northeast France was found to be a wintering area for an introduced population of Greylags established southwest of Stockholm in Sweden, and the geese wintering on the Camargue in southern France were recruited mainly from central Europe. Numbers wintering in France have increased in line with the general increase in the European Greylag Goose population, whereas numbers on passage in France have not increased in the same way, possibly due to a northward shift in the winter distribution of Greylags across Europe. The numbers wintering in France are, however, still small compared to other areas along the flyway.
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| 20. |
- Nilsson, Leif
(författare)
-
Long-term trends in numbers of Whooper Swans Cygnus cygnus breeding and wintering in Sweden
- 2014
-
Ingår i: Wildfowl. - 0954-6324. ; 64, s. 197-206
-
Tidskriftsartikel (refereegranskat)abstract
- The Whooper Swan Cygnus cygnus was a rare breeding species in Sweden during the early years of the 20th century, when total numbers likely consisted of only 20 pairs. Recent decades have however seen a marked increase in numbers and a spread in the swans’ distribution, with the number of pairs breeding in the two northernmost provinces rising from 310 to 2,700 pairs between two main surveys, in 1972–75 and 1997. This paper documents continued long-term (1967–2014) increases in numbers of Whooper Swans breeding and wintering in Sweden, based on data collected by the Swedish Bird Monitoring Programme and during the mid-winter International Waterbird Counts (IWC). Most recent estimates for the country indicate that there are now 5,400 breeding pairs during the summer and close to 10,000 individuals present in normal or mild winters.
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| 21. |
- Nilsson, Leif, et al.
(författare)
-
Natal and breeding dispersal in the Baltic Greylag Goose Anser anser.
- 2001
-
Ingår i: Wildfowl. - 0954-6324. ; 52, s. 21-30
-
Tidskriftsartikel (refereegranskat)abstract
- Dispersai from the centre o f the breeding range of the BalticGreylag Goose Anser anser was studied using observationsof individuals with neck collars. The median natal dispersal distance was 0 km in females and 25 km in mates, respectively. A ll of the females recruited to w ith in7 km o f where they had been reared, 87% to the natal lake and 11% toneighbouring water bodies. Of the mates, only 11% rec ruited to the natallake, while one individual was found more than 1,000 km from its place ofbirth. Even though the males dispersed to a g reater distance within the population's breeding range, th e ir distribution was s till highly skewed towardsth e ir point o f origin. Two thirds of a ll mates recruited within 30 km of the sitewhere they had been reared. Once recruited, both sexes exhibited anextremely strong p h ilopatry to th e ir breeding area. Only 1.5% o f the malesand 0.5% o f the females changed breeding site between successive years.A lt breeding dispersal occurred within the local population, and in no caseexceeded 6 km.
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| 22. |
- Nilsson, Leif
(författare)
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Possible density-dependence in an expanding population of Greylag Goose Anser anser in South Sweden.
- 2016
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Ingår i: Wildfowl. - 0954-6324. ; 66, s. 98-111
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Tidskriftsartikel (refereegranskat)abstract
- Neck-banded Greylag Geese Anser anser breeding in southwest Sweden were studied from 1984–2012 inclusive, to determine annual variation in the number of breeding pairs, reproductive success and survival rates, as part of a larger programme of monitoring individual geese across the Nordic countries. Numbers breeding in the study area increased from 120 pairs in 1984 to 1,240 pairs in 2008, followed by a decrease to about 800 pairs. As the number of nesting pairs of Greylag Geese increased, the proportion of pairs producing young decreased, suggesting densitydependence effects on the production of young. The decline in the proportion of breeding pairs occurred later at a lake thought to offer better feeding areas for the young than at a second lake in the study area. There was no marked decrease in the mean brood size among productive pairs, only a slight decrease in the fledging rate. There was also no clear trend during the study in first-year survival rates for geese neck-banded at fledging.
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| 23. |
- Nilsson, Leif, et al.
(författare)
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Why should Greylag Goose Anser anser parents rear offspring of others?
- 2003
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Ingår i: Wildfowl. - 0954-6324. ; 54, s. 25-37
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Tidskriftsartikel (refereegranskat)abstract
- The benefits and costs of rearing large broods were studied in a population of neck collared Greylag Geese in Scania, southernmost Sweden. Families were divided into four groups according to brood size: 1-4, 5-8, 9-12 and >12 young. Gosling survival showed a significant positive relationship with brood size on arrival at the rearing area. First-year and third-year local survival, as well as breeding recruitment, showed a significant positive relationships with brood size at fledging. For adults rearing large broods, no costs were detected during the year following that when they fledged >8 young; both survival rate and reproductive success exceeded the long-term averages.
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| 24. |
- Nilsson, Leif
(författare)
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Wintering diving duck populations in the Öresund, Southern Sweden, in relation to available food Resources.
- 2005
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Ingår i: Wildfowl. - 0954-6324. ; 55, s. 61-76
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Tidskriftsartikel (refereegranskat)abstract
- Intensive surveys of staging and wintering diving ducks in the Öresund area,southern Sweden, were undertaken during the winters 1995/96, 1996/97 and1997/98 as a part of the Environmental Impact Assessment (EIA) related to theestablishment of a Fixed Link (bridge–tunnel–artificial island) between Swedenand Denmark. Monitoring of the benthic fauna made it possible to compare thecalculated food requirements of the diving duck populations with their foodresources. Overall, the diving ducks (mainly Tufted Duck Aythya fuligula, ScaupAythya marila and Goldeneye Bucephala clangula) consumed between 2.6% and4.6 % of the standing crop of suitable food organisms. It is, however, probable that higher proportions of the prey are consumed in the shallowest areas compared to areas with deeper water. A prolonged period of ice cover during one of the study years made a large proportion of the feeding areas unavailable, but the main mussel beds were still free of ice because of strong currents so this had only limited impact on the food availability for the ducks.
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| 25. |
- Stafford, Joshua D., et al.
(författare)
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Spring migration of waterfowl in the northern hemisphere : a conservation perspective
- 2014
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special Issue 4, s. 70-85
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Tidskriftsartikel (refereegranskat)abstract
- Spring migration is a key part of the annual cycle for waterfowl populations in the northern hemisphere, due to its temporal proximity to the breeding season and because resources may be limited at one or more staging sites. Research based on field observations during spring lags behind other periods of the year, despite the potential for fitness consequences through diminished survival or cross-seasonal effects of conditions experienced during migration. Consequently, conservation strategies for waterfowl on spring migration are often only refined versions of practices used during autumn and winter. Here we discuss the current state of knowledge of habitat requirements for waterfowl at their spring migratory sites and the intrinsic and extrinsic factors that lead to variability in those requirements. The provision of plant foods has become the main conservation strategy during spring because of the birds’ energy requirements at this time, not only to fuel migration but to facilitate early clutch formation on arrival at the breeding grounds. Although energy sources are important to migrants, there is little evidence on the extent to which the availability of carbohydrate-based food is limiting for many migratory waterfowl populations. Such limitation is relatively unlikely among populations that exploit agricultural grain during migration (e.g. arctic-nesting geese), suggesting that conservation strategies for these populations may be misplaced. In general, however, we found few cases in which an ecological understanding of spring-migrating waterfowl was sufficient to indicate true resource limitation during migration, and still fewer cases where conservation efforts ameliorated these limitations. We propose a framework that aims to address knowledge gaps and apply empirical research results to conservation strategies based on documented limitations and associated fitness impacts on migrating waterfowl. Such a strategy would improve allocation of scarce conservation resources during spring migration and greatly improve ecological understanding of migratory waterfowl and their habitats in the northern hemisphere.
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| 26. |
- Stafford, Joshua D., et al.
(författare)
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Spring migration of waterfowl in the northern hemisphere : a conservation perspective
- 2014
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Ingår i: Wildfowl. - : Wildfowl and Wetlands Trust. - 0954-6324. ; :Special Issue 4, s. 70-85
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Tidskriftsartikel (refereegranskat)abstract
- Spring migration is a key part of the annual cycle for waterfowl populations in the northern hemisphere, due to its temporal proximity to the breeding season and because resources may be limited at one or more staging sites. Research based on field observations during spring lags behind other periods of the year, despite the potential for fitness consequences through diminished survival or cross-seasonal effects of conditions experienced during migration. Consequently, conservation strategies for waterfowl on spring migration are often only refined versions of practices used during autumn and winter. Here we discuss the current state of knowledge of habitat requirements for waterfowl at their spring migratory sites and the intrinsic and extrinsic factors that lead to variability in those requirements. The provision of plant foods has become the main conservation strategy during spring because of the birds’ energy requirements at this time, not only to fuel migration but to facilitate early clutch formation on arrival at the breeding grounds. Although energy sources are important to migrants, there is little evidence on the extent to which the availability of carbohydrate-based food is limiting for many migratory waterfowl populations. Such limitation is relatively unlikely among populations that exploit agricultural grain during migration (e.g. arctic-nesting geese), suggesting that conservation strategies for these populations may be misplaced. In general, however, we found few cases in which an ecological understanding of spring-migrating waterfowl was sufficient to indicate true resource limitation during migration, and still fewer cases where conservation efforts ameliorated these limitations. We propose a framework that aims to address knowledge gaps and apply empirical research results to conservation strategies based on documented limitations and associated fitness impacts on migrating waterfowl. Such a strategy would improve allocation of scarce conservation resources during spring migration and greatly improve ecological understanding of migratory waterfowl and their habitats in the northern hemisphere.
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