We addressed how species number and pair density in guilds of co‐existing species is related to habitat structure, and to the abundance and diversity of food resources using the assemblage of seven species of dabbling ducks (genus Anas) breeding in 60 lakes distributed over six regions in temperate north Europe Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey We found no effect of lake size or prey size diversity on species richness Pair density was correlated with the percentage of shoreline with horsetails (Equisetum), by habitat structural diversity and by the abundance of emergent invertebrate prey Neither prey size diversity nor abundance of aquatic prey correlated with pair density Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability
Identification of conservation priorities is a fundamental issue for successful nature conservation. This can be done by looking at population trends of species in different habitats. Boreal zone is the key breeding area for many Eurasian waterbirds. Wetlands of the boreal zone can be roughly classified into two different groups: nutrient‐poor oligotrophic and nutrient‐rich eutrophic water ecosystems. Earlier work has shown that eutrophic lake‐specialist species have declined compared with generalists and species preferring oligotrophic lakes. However, it is not known if species that live in both habitats show habitat‐specific population trends. We used monitoring data of breeding waterbirds in Finland from 1986 to 2013 to evaluate habitat‐specific population trends in five generalist duck species, which mostly overwinter in the coastal waters of West Europe. Population trend of tufted duck was highly significantly more positive in oligotrophic wetlands compared with populations in eutrophic wetlands, and two other species had similar but weaker effects. In addition, we established bird population state indicators for oligotrophic and eutrophic water ecosystems in Finland. The indicators revealed that the populations in eutrophic wetlands have on average halved since early 1990s. The populations in oligotrophic wetlands have remained stable, except a moderate decline since the late 2000s. Our findings support the idea that the waterbird populations of the eutrophic wetlands are in serious trouble. This is likely due to over‐eutrophication of these ecosystems. Conservation and management actions should be urgently taken to halt the loss of biodiversity in these globally threatened freshwater ecosystems.
The consequences of climate change for bird populations have received much attention in recent decades, especially amongst cavity-nesting songbirds, yet little has been written on ducks (Anatidae) despite these being major elements of wetland diversity and important quarry species. This paper reviews the major known consequences of climate change for birds in general, and relates these to the limited information available specifically for ducks. Climate change can influence migration distance and phenology, potentially affecting patterns of mortality, as well as distribution and reproductive success in ducks. Studies addressing effects of climate change are, however, restricted to very few duck species, including mallard Anas platyrhynchos and common eider Somateria mollissima. Shifts in winter duck distributions have been observed, whereas the mismatch hypothesis (mistiming between the periods of peak energy requirements for young and the peak of seasonal food availability) has received limited support with regard to ducks. We propose a range of monitoring initiatives, including population surveys, breeding success monitoring schemes and individual duck marking, which should later be integrated through population modelling and adaptive management to fill these gaps.
Habitat use of mallard Anas platvrhynchos, teal A crecca. wigeon A penelope and goldeneye Bucephala clangula was studied m southern Finland during 1988–1991 Emphasis included evaluation of the importance of food and vegetation structure and revealing of the patterns of habitat use throughout the breeding season Average lake scores of pairs, broods, and juveniles of all species were on the luxunant end of a principal component analysis axis describing habitat structure A more detailed examination, however, revealed clear differences in habitat distributions both between and within species Generally, habitat distributions seemed to shift toward the luxuriant from pairs to broods However, goldeneye juveniles used both the most luxuriant and the poorest habitats more than expected When all phases of the breeding cycle are considered, habitat luxuriance seemed to be more important for dabbling ducks and nektonic invertebrates more important for the goldeneye Emerging insects were most important to the teal
It is an axiom in ecology that knowing the sheer number of individuals in a population is of very little help if the objective is to understand future and past changes in population size. Yet, this is exactly how migratory European ducks are monitored, many of which are important quarry species in several countries. We argue that present monitoring is insufficient to address objectives of wise use and sustainability such as those emphasised in recent management directives and multilateral international agreements. The two main problems are the almost total lack of reliable data on recruitment and mortality. We advocate a pan-European monitoring system based on undisputed scientific principles; i.e. a long-term, coordinated and standardised scheme that produces data about vital rates of duck populations as well as about harvest size. Data from such a scheme can be used by game biologists to produce predictive tools, thus providing a functional basis for management decisions for adaptive harvesting and conservation alike.
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