| 1. |
- Elmberg, Johan, et al.
(author)
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Farmed European mallards are genetically different and cause introgression in the wild population following releases
- 2016
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Conference paper (peer-reviewed)abstract
- The practice of restocking already viable populations to increase harvest potential has since long been common in forestry, fisheries and wildlife management. The potential risks of restocking native species have long been overshadowed by the related issue of invasive alien species. However, during the last decade releases of native species with potentially non-native genome have received more attention. A suitable model to study genetic effects of large-scale releases of native species is the Mallard Anas platyrhynchos, being the most widespread duck in the world, largely migratory, and an important quarry species. More than 3 million unfledged hatchlings are released each year around Europe to increase local harvest. The aims of this study were to determine if wild and released farmed Mallards differ genetically, if there are signs of previous or ongoing introgression between wild and farmed birds, and if the genetic structure of the wild Mallard population has changed since large-scale releases started in Europe in the 1970s. Using 360 Single Nucleotide Polymorphisms (SNPs) we found that the genetic structure differed among historical wild, present-day wild, and farmed Mallards in Europe. We also found signs of introgression in the wild Mallard population, that is, individuals with a genetic background of farmed stock are part of the present free-living population. Although only a small proportion of the released Mallards appears to survive to merge with the free-living breeding population, their numbers are still so large that the genetic impact may have significance for the wild population in terms of individual survival and longterm fitness.
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| 2. |
- Elmberg, Johan, et al.
(author)
-
Farmed European mallards are genetically different and cause introgression in the wild population following releases
- 2016
-
Conference paper (other academic/artistic)abstract
- The practice of restocking already viable populations to increase harvest potential has since long been common in forestry, fisheries and wildlife management. The potential risks of restocking native species have long been overshadowed by the related issue of invasive alien species. However, during the last decade releases of native species with potentially non-native genome have received more attention. A suitable model to study genetic effects of large-scale releases of native species is the Mallard Anas platyrhynchos, being the most widespread duck in the world, largely migratory, and an important quarry species. More than 3 million unfledged hatchlings are released each year around Europe to increase local harvest. The aims of this study were to determine if wild and released farmed Mallards differ genetically, if there are signs of previous or ongoing introgression between wild and farmed birds, and if the genetic structure of the wild Mallard population has changed since large-scale releases started in Europe in the 1970s. Using 360 Single Nucleotide Polymorphisms (SNPs) we found that the genetic structure differed among historical wild, present-day wild, and farmed Mallards in Europe. We also found signs of introgression in the wild Mallard population, that is, individuals with a genetic background of farmed stock are part of the present free-living population. Although only a small proportion of the released Mallards appears to survive to merge with the free-living breeding population, their numbers are still so large that the genetic impact may have significance for the wild population in terms of individual survival and longterm fitness.
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| 3. |
- Fox, Anthony D., et al.
(author)
-
Recent changes in the abundance of Common Pochard Aythya ferina breeding in Europe
- 2016
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In: Wildfowl. - 0954-6324. ; 66, s. 22-40
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Research review (peer-reviewed)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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| 4. |
- Guillemain, Matthieu, et al.
(author)
-
Agent-based modeling may help to merge research traditions in foraging ecology in Europe and North America
- 2017
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In: Wildlife Society bulletin. - 0091-7648 .- 1938-5463. ; 41:1, s. 170-176
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Journal article (peer-reviewed)abstract
- Although ducks have long been popular research subjects in both North America and Europe, geographical divergences in research orientation have developed during the past several decades for studying foraging ecology. In North America, foraging studies largely focused on the population level with an emphasis on foraging energetics aimed at improving waterfowl production through increased carrying capacity of wetlands in breeding areas, an approach later expanded to nonbreeding grounds. In Europe, studies have instead focused on inter-individual differences in behavior of foraging ducks, with an emphasis on individual efficiency (e.g., methods, intake rate, patch choice) within the framework of optimal foraging theory. We suggest that agent-based models (also termed individual-based behavior models), which aim to predict habitat use from the heterogeneous behavior of different individual agents, can help to unify these approaches and would benefit considerably from increased collaboration and integration of the approaches of both North American and European researchers.
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| 5. |
- Guillemain, Matthieu, et al.
(author)
-
Agent-based modeling may help to merge research traditions in foraging ecology in Europe and North America
- 2017
-
In: Wildlife Society Bulletin. - : Wiley-Blackwell. - 0091-7648 .- 1938-5463. ; 41:1, s. 170-176
-
Journal article (peer-reviewed)abstract
- Although ducks have long been popular research subjects in both North America and Europe, geographical divergences in research orientation have developed during the past several decades for studying foraging ecology. In North America, foraging studies largely focused on the population level with an emphasis on foraging energetics aimed at improving waterfowl production through increased carrying capacity of wetlands in breeding areas, an approach later expanded to nonbreeding grounds. In Europe, studies have instead focused on inter-individual differences in behavior of foraging ducks, with an emphasis on individual efficiency (e.g., methods, intake rate, patch choice) within the framework of optimal foraging theory. We suggest that agent-based models (also termed individual-based behavior models), which aim to predict habitat use from the heterogeneous behavior of different individual agents, can help to unify these approaches and would benefit considerably from increased collaboration and integration of theapproaches of both North American and European researchers.
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| 6. |
- Guillemain, Matthieu, et al.
(author)
-
Combined effects of climate change and fluctuating habitat quality on the distribution of ducks in southern Europe
- 2016
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In: 7th North American Duck Symposium.
-
Conference paper (peer-reviewed)abstract
- Changes in waterfowl ranges over the last decades are increasingly reported, both in North America and in Europe. The relative importance of different winter quarters may fluctuate under the influence of changing local habitat conditions, as well as according to general trends caused by global climate change. Several European duck species have shifted their winter range to the North-East, i.e. the distance between breeding and wintering grounds was reduced, in a pattern consistent with a global temperature increase. In northern countries, this could also indicate an increasing proportion of sedentary birds. We compared the geographic distribution of recoveries of bands fitted to Mallard (Anas platyrhynchos) and Common Teal (A. crecca) in Camargue, southern France, over the last 60 years. Close to 75,000 ducks were banded since the early 1950s. Band recoveries occurred to a much greater extent in the Camargue area than in other parts of the flyways during the last decade compared to earlier years: as opposed to earlier studies, recoveries of Camargue-ringed ducks are increasingly made to the South-West. For migratory Teal, this indicates an increased faithfulness to the Camargue winter quarter. For Mallard, though, some birds may have become around-the-year residents: while the distance from banding site to recovery location was >400 km between the 1950s and 1970s, it is <75 km nowadays. Several hypotheses are proposed to explain these changes in European duck distributions. Survival analyses are also carried out, which help assessing whether changes in geographic distribution have also translated into altered demographic rates. Besides the overriding effects of climate change in the long-term, the present results suggest that local habitat management practices still have the potential to greatly affect the distribution of waterfowl.
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| 7. |
- Guillemain, Matthieu, et al.
(author)
-
Combined effects of climate change and fluctuating habitat quality on the distribution of ducks in southern Europe
- 2016
-
Conference paper (other academic/artistic)abstract
- Changes in waterfowl ranges over the last decades are increasingly reported, both in North America and in Europe. The relative importance of different winter quarters may fluctuate under the influence of changing local habitat conditions, as well as according to general trends caused by global climate change. Several European duck species have shifted their winter range to the North-East, i.e. the distance between breeding and wintering grounds was reduced, in a pattern consistent with a global temperature increase. In northern countries, this could also indicate an increasing proportion of sedentary birds. We compared the geographic distribution of recoveries of bands fitted to Mallard (Anas platyrhynchos) and Common Teal (A. crecca) in Camargue, southern France, over the last 60 years. Close to 75,000 ducks were banded since the early 1950s. Band recoveries occurred to a much greater extent in the Camargue area than in other parts of the flyways during the last decade compared to earlier years: as opposed to earlier studies, recoveries of Camargue-ringed ducks are increasingly made to the South-West. For migratory Teal, this indicates an increased faithfulness to the Camargue winter quarter. For Mallard, though, some birds may have become around-the-year residents: while the distance from banding site to recovery location was >400 km between the 1950s and 1970s, it is <75 km nowadays. Several hypotheses are proposed to explain these changes in European duck distributions. Survival analyses are also carried out, which help assessing whether changes in geographic distribution have also translated into altered demographic rates. Besides the overriding effects of climate change in the long-term, the present results suggest that local habitat management practices still have the potential to greatly affect the distribution of waterfowl.
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| 8. |
- Guillemain, Matthieu, et al.
(author)
-
Foraging, nutrition, and energetics of waterfowl : a European perspective
- 2016
-
In: 7th North American Duck Symposium.
-
Conference paper (peer-reviewed)abstract
- Much attention has historically been devoted to feeding ecology of waterfowl, providing an extensive research record for Europe and North America alike. However, research in this field has gradually followed different paths on the two continents. American scientists have adopted a more applied perspective, often aiming at assessing the extent to which food requirements of waterfowl can be fulfilled in different habitats, and how management of these can increase carrying capacity. As opposed to this "energetic" approach, European scientists have rather framed their studies in a "behavioral" perspective, using waterfowl as model species for more theoretical approaches to foraging ecology. Consequently, while North American research has most often been carried out at the scale of waterfowl populations, the individual bird has more frequently been the scale of study in Europe. We present three examples of such European studies: first, a detailed analysis of the trade-offs made by dabbling ducks between foraging and anti-predator vigilance, leading to divergent strategies to face gradual food depletion during the winter. Second, we do a flyway-scale analysis of duck foraging needs and behavior, from Mediterranean wintering grounds to breeding sites in the Boreal, and point out the main hurdles faced by these birds across their annual cycle. Such detailed European studies can provide useful parameter values to fuel modern agent-based models of habitat use and carrying capacity developed in North America, hence cross-fertilizing the approaches on the two continents. This is exactly what our third example is about; namely adapting the SWAMP model developed in California to better understand and predict the use of harvested rice fields by wintering ducks in southern France.
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| 9. |
- Guillemain, Matthieu, et al.
(author)
-
Foraging, nutrition, and energetics of waterfowl : a European perspective
- 2016
-
Conference paper (other academic/artistic)abstract
- Much attention has historically been devoted to feeding ecology of waterfowl, providing an extensive research record for Europe and North America alike. However, research in this field has gradually followed different paths on the two continents. American scientists have adopted a more applied perspective, often aiming at assessing the extent to which food requirements of waterfowl can be fulfilled in different habitats, and how management of these can increase carrying capacity. As opposed to this "energetic" approach, European scientists have rather framed their studies in a "behavioral" perspective, using waterfowl as model species for more theoretical approaches to foraging ecology. Consequently, while North American research has most often been carried out at the scale of waterfowl populations, the individual bird has more frequently been the scale of study in Europe. We present three examples of such European studies: first, a detailed analysis of the trade-offs made by dabbling ducks between foraging and anti-predator vigilance, leading to divergent strategies to face gradual food depletion during the winter. Second, we do a flyway-scale analysis of duck foraging needs and behavior, from Mediterranean wintering grounds to breeding sites in the Boreal, and point out the main hurdles faced by these birds across their annual cycle. Such detailed European studies can provide useful parameter values to fuel modern agent-based models of habitat use and carrying capacity developed in North America, hence cross-fertilizing the approaches on the two continents. This is exactly what our third example is about; namely adapting the SWAMP model developed in California to better understand and predict the use of harvested rice fields by wintering ducks in southern France.
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| 10. |
- Guillemain, Matthieu, et al.
(author)
-
Still worth the travel? : changes in Camargue teal migration patterns, body condition and demographic parameters over 60 years
- 2015
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In: 4th Pan-European Duck Symposium, Hangö, Finland, 8-11/4 2015. ; , s. 28-
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Conference paper (peer-reviewed)abstract
- Climate and habitat changes linked with human activities have profoundly modified the road maps of waterfowl across their geographic ranges. If new breeding grounds open to the North, traditional wintering sites may gradually get deserted by birds short-stopping during the autumn and shifting their nonbreeding distribution. More than 60,000 ringing data were collected from wintering Teal (Anas crecca) in the area from the early 1950s to the beginning of the 2010s. Migration patterns have changed with birds now arriving much earlier, and overall population movements being much reduced during winter. The body condition of Camargue-wintering Teal has improved dramatically compared to the pre-1970 era, which could be a cause and/or a consequence of such changes in migration processes: Teal may arrive increasingly early in the year because artificial summer flooding of wetlands and baiting now provide suitable habitat and abundant accessible food. In turn, reduced movements linked with greater residency in the Camargue would impose smaller use of the body reserves. The comparison of Teal turnover and survival rates during historical (1950s- 1970s) and modern (post-2002) years provides some insight as to whether the situation has gradually improved for these birds. Conversely, the sustained use of the Camargue could simply reflect these birds being lured by artificially increased availability of food, which they would use at the expense of their survival rate, hence with no positive consequences in terms of population dynamics.
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