| 1. |
- Elmberg, Johan, 1960-, et al.
(author)
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Population change in breeding boreal waterbirds in a 25‐year perspective : what characterises winners and losers?
- 2019
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In: Freshwater Biology. - : Wiley: 12 months. - 0046-5070 .- 1365-2427. ; 65:2, s. 167-177
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Journal article (peer-reviewed)abstract
- Understanding drivers of variation and trends in biodiversity change is a general scientific challenge, but also crucial for conservation and management. Previous research shows that patterns of increase and decrease are not always consistent at different spatial scales, calling for approaches combining the latter. We here explore the idea that functional traits of species may help explaining divergent population trends.Complementing a previous community level study, we here analyse data about breeding waterbirds on 58 wetlands in boreal Fennoscandia, covering gradients in latitude as well as trophic status. We used linear mixed models to address how change in local abundance over 25 years in 25 waterbird species are associated with life history traits, diet, distribution, breeding phenology, and habitat affinity.Mean abundance increased in 10 species from 1990/1991 to 2016, whereas it decreased in 15 species. Local population increases were associated with species that are early breeders and have small clutches, an affinity for luxurious wetlands, an herbivorous diet, and a wide breeding range rather than a southern distribution. Local decreases, by contrast, were associated with species having large clutches and invertivorous diet, as well as being late breeders and less confined to luxurious wetlands. The three species occurring on the highest number of wetlands all decreased in mean abundance.The fact that early breeders have done better than late fits well with previous research about adaptability to climate change, that is, response to earlier springs. We found only limited support for the idea that life history traits are good predictors of wetland level population change. Instead, diet turned out to be a strong candidate for an important driver of population change, as supported by a general decrease of invertivores and a concomitant increase of large herbivores.In a wider perspective, future research needs to address whether population growth of large‐bodied aquatic herbivores affects abundance of co‐occurring invertivorous species, and if so, if this is due to habitat alteration, or to interference or exploitative competition.
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| 2. |
- Holopainen, Sari, et al.
(author)
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Sustainable management of migratory European ducks : finding model species
- 2018
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In: Wildlife Biology. - : Nordic Council for Wildlife Research (NKV). - 0909-6396 .- 1903-220X.
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Journal article (peer-reviewed)abstract
- Eurasian migratory duck species represent a natural resource shared between European countries. As is evident throughout human harvest history, lack of coordinated management and monitoring at appropriate levels often leads to ‘the tragedy of the commons’, where shared populations suffer overexploitation. Effective management can also be hampered by poor understanding of the factors that limit and regulate migratory populations throughout their flyways, and over time. Following decades of population increase, some European duck populations now show signs of levelling off or even decline, underlining the need for more active and effective management. In Europe, the existing mechanisms for delivering effective management of duck populations are limited, despite the need and enthusiasm for establishing adaptive management (AM) schemes for wildlife populations. Existing international legal agreements already oblige European countries to sustainably manage migratory waterbirds. Although the lack of coordinated demographic and hunting data remains a challenge to sustainable management planning, AM provides a robust decision-making framework even in the presence of uncertainty regarding demographic and other information. In this paper we investigate the research and monitoring needs in Europe to successfully apply AM to ducks, and search for possible model species, focusing on freshwater species (in contrast to sea duck species) in the East Atlantic flyway. Based on current knowledge, we suggest that common teal Anas crecca, Eurasian wigeon Mareca penelope and common goldeneye Bucephala clangula represent the best species for testing the application of an AM modelling approach to duck populations in Europe. Applying AM to huntable species with relatively good population data as models for broader implementation represents a cost effect to develop AM on a European flyway scale for ducks, and potentially other waterbirds in the future.
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| 3. |
- Holopainen, Sari, et al.
(author)
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Sustainable management of migratory European ducks : finding model species
- 2018
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Conference paper (other academic/artistic)abstract
- Eurasian migratory ducks are a natural resource shared between multiple European countries. Due to lack of flyway-level management and monitoring, there is a risk of “the tragedy of the commons” arising, where populations are overexploited. Effective management may also be hindered by a poor understanding of the factors that limit and regulate migratory populations throughout their flyways, and over time. Following decades of population increase, some European duck populations now show signs of levelling off or even decline, underlining the need for more active management. In Europe, we lack effective common tools to manage duck populations, despite the need and enthusiasm for establishing flyway-level adaptive management (AM) schemes for migratory birds. There are several international legal agreements (e.g. EEC Birds Directive, AEWA) that oblige European countries to sustainably manage migratory birds and their habitats. Although the lack of coordinated demographic and hunting data remains a challenge to sustainable management planning for waterfowl, AM provides a robust decision-making framework even in the presence of uncertainty.We investigate the research and monitoring needs in Europe to successfully apply AM to ducks, and search for possible model species, focusing on freshwater duck species. Our geographical focus is NW Europe (excluding Russia), the area utilized by ducks in the East-Atlantic flyway. Based on current knowledge and their wide distribution, we suggest that Common Teal Anas crecca, Eurasian Wigeon Mareca penelopeand Common Goldeneye Bucephala clangulawould be the best species for testing the application of an AM modelling approach for ducks in Europe. Applying AM to huntable species with relatively good population data as models for broader implementation represents a cost effective way of starting to develop AM on a European flyway scale for ducks and other harvested waterbirds.
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| 4. |
- Pöysä, Hannu, et al.
(author)
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Changes in species richness and composition of boreal waterbird communities : a comparison between two time periods 25 years apart
- 2019
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In: Scientific Reports. - : Nature Publishing Group: Open Access Journals - Option C / Nature Publishing Group. - 2045-2322. ; 9:1
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Journal article (peer-reviewed)abstract
- Global measures of biodiversity indicate consistent decline, but trends reported for local communitiesare more varied. Therefore, we need better understanding of mechanisms that drive changes in diversity of local communities and of differences in temporal trends between components of local diversity, such as species richness and species turnover rate. Freshwater ecosystems are vulnerable to multiple stressors, and severe impacts on their biodiversity have been documented. We studied species richness and composition of local boreal waterbird communities in 1990/1991 and 2016 at 58 lakes distributed over six regions in Finland and Sweden. The study lakes represented not only local trophic gradients but also a latitudinal gradient in the boreal biome. While species richness tended to be lower in 2016 than in 1990/1991, species turnover was relatively high. Within foraging guilds, local species richness of diving ducks and surface feeding waterbirds decreased, whereas that of large herbivores increased. The number of species gained in local communities was higher in lakes with rich vegetation than in lakes with sparse vegetation. Conservation of boreal freshwater ecosystems would benefit from recognizing hat large-scale environmental changes can affect local diversity via processes operating atfiner scales.
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| 5. |
- Pöysä, Hannu, et al.
(author)
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Habitat associations and habitat change : seeking explanation for population decline in breeding Eurasian wigeon Anas penelope
- 2017
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In: Hydrobiologia. - : Springer Verlag (Germany). - 0018-8158 .- 1573-5117. ; 785:1, s. 207-217
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Journal article (peer-reviewed)abstract
- We explored whether the recent large-scale population decline of Eurasian wigeon (Anas penelope) in Europe may be linked to long-term vegetation changes in their boreal breeding wetlands. First, we assessed the importance of Equisetum, Phragmites, and Carex stands in lake selection by pairs and in foraging habitat selection by broods. Second, in 2013–2014 we revisited 58 lakes in Sweden and Finland studied in 1990–1991, to examine if there had been any long-term change in the abundance of habitat types preferred by wigeon. Finally, using continuous long-term data on breeding numbers of wigeon in 18 of the lakes studied in 1990–1991, we examined if wigeon numbers had changed at lakes where the habitat also had changed. We found that lake occupation of nesting wigeon pairs and foraging habitat use of broods were associated with the extent of Equisetum stands. The presence and abundance of this preferred habitat declined dramatically from 1990–1991 to 2013–2014 in the lakes from which the presence–absence data of wigeon emanate. Breeding numbers of wigeon showed a long-term declining trend in lakes where Equisetum has decreased. Our results imply that the recent population decline of wigeon in Europe may be linked to decrease of Equisetum habitat.
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| 6. |
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| 7. |
- Pöysä, Hannu, et al.
(author)
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Recovering Whooper Swans do not cause a decline in Eurasian Wigeon via their grazing impact on habitat
- 2018
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In: Journal of Ornithology = Journal fur Ornithologie. - : Springer Science Business Media. - 0021-8375 .- 1439-0361. ; 159, s. 447-455
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Journal article (peer-reviewed)abstract
- The Whooper Swan (Cygnus cygnus) is a good example of successful conservation, with rapidly growing numbers in Fennoscandia in recent decades. To the contrary, Eurasian Wigeon (Mareca penelope) shows a strong negative trend in breeding numbers, which raises conservation concerns. Previous research suggests a causal link between recent population trajectories of the two species. Both preferentially breed on wetlands with abundant horsetail (Equisetum spp.), a plant providing food for Whooper Swan and crucial feeding microhabitat for Eurasian Wigeon broods. We here test predictions based on the hypothesis that grazing on Equisetum by Whooper Swan reduces breeding habitat or breeding habitat quality for Eurasian Wigeon. We use data from 60 lakes in which waterfowl were counted in 1990–1991 and 2016, and Equisetum was mapped in 1990–1991 and 2013–2014. Lakes colonized by Whooper Swan typically had more abundant Equisetum vegetation in the past than lakes not colonized. Lake-specific decrease of Equisetum was not associated with colonization by Whooper Swan. The number of lakes occupied by Eurasian Wigeon decreased, but the decrease was not stronger on lakes colonized by Whooper Swan than on those that were not. Contrary to our prediction, current Eurasian Wigeon abundance was positively associated with Whooper Swan abundance. Moreover, Eurasian Wigeon did not decrease more on lakes from which Equisetum disappeared than on lakes in which there was still Equisetum left. This study does not support the idea that Whooper Swan affects Eurasian Wigeon negatively by grazing on Equisetum.
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| 8. |
- Söderquist, Pär, et al.
(author)
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Effects of released farmed mallards on species richness of breeding waterbirds and amphibians in natural, restored and constructed wetlands
- 2021
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In: Wildlife Biology. - 0909-6396 .- 1903-220X. ; 2021, s. 1-9
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Journal article (peer-reviewed)abstract
- Common practices in current game management are wetland restoration and creation, as well as releases of quarry species. We studied the impact of releases of mallard ducklings on species richness of wild waterbirds and amphibians on three types of wetlands: natural, constructed and restored. Data on species richness, macrophyte cover and water characteristics (total phosphorous and pH) were collected at 32 sites in an agricultural landscape in southern Sweden. In total, 14 species of waterbirds were recorded, ranging from zero to seven per wetland and survey. Amphibians were present in 24 of the 32 wetlands; in total five species were found, ranging from zero to three per wetland. By using generalized linear modelling we found that wetland type best predicted waterbird species richness. Constructed wetlands had significantly more waterbird species, regardless of whether they were used for mallard releases or not. There were breeding amphibians in 62% of natural, 100% of restored and 77% of constructed wetlands. Breeding amphibians were present in 84% of wetlands without, and in 62% of wetlands with releases. However, included variables did not explain amphibian species richness in the wetlands. Releasing large numbers of mallards on a wetland and providing food ad libitum is likely to affect water quality, nutrient availability and predation pressure. Indeed, phosphorous levels were significantly higher in release wetlands, but no differences were found between wetland types.This means that mallard releases may increase nutrient loads in environments that are already eutrophied. However, in our study system releases did not influence species richness of waterbirds and amphibians locally. Constructing wetlands for mallard releases can thus have positive local effects on species richness.
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