The effect of inter-specific differences in morphology and behaviour between dabbling duck species on the endozoochorous dispersal of aquatic organisms
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Wetlands are highly threatened by human impact. About half of the world’s wetlands were lost in the past century, resulting in larger distances between separate wetland areas. As a consequence, there is an increased isolation of these areas and a reduction in dispersal between them. In order to gain knowledge about the effects of wetland loss on the biodiversity of these areas, more information is needed about vectors regulating dispersal of organisms between wetlands. Because of their long-distance movements, diet composition, high abundance and widespread distribution in wetlands, dabbling ducks are considered important dispersal-vectors in these areas. During this study, the effects of inter-specific differences in morphology and behaviour between dabbling duck species on the endozoochorous dispersal of aquatic organisms was analyzed by means of a literature research. It was shown that different species of dabbling ducks are highly different in the resources they consume when there is a high amount of competition, or when the primary resource is scarce. Whether these inter-specific differences in diets result in differences in dispersal of aquatic organisms needs to be investigated. Furthermore it became clear that inter-specific differences between seeds are more important determinants of GRT than morphological differences between duck species. However, differences in movement patterns between dabbling duck species probably do influence different dispersal patterns of aquatic organisms. Different duck species exhibit a great variety of long-distance movements. Besides long-distance movements, short distance movements are also important for the dispersal of aquatic organisms. The global population size of a duck species determines the impact that varying duck species have on the dispersal of aquatic organisms. Even though species containing extremely large populations are probably more important for dispersal of aquatic organisms on a global scale, highly endangered duck species might be important for the dispersal of aquatic organisms on a local scale. Despite the fact that quite a lot is known about the dispersal of aquatic organisms by dabbling ducks, there are still many factors that need to be elucidated. More knowledge about differences in dispersal between varying dabbling duck species could not only lead to better measures to conserve wetlands, but also to stricter conservation measures to protect endangered dabbling duck species.