Morphology-Mediated Niche Organization in a Guild of Dabbling Ducks

Morphology-mediated niche organization among six dabbling duck species was studied by recognizing the morphological (neck length, bill morphology) differences between the species and testing the compatibility of these differences with ecological data (feeding habitat, depth and method, food). The following main results emerged: (1) Differences in neck (and body) length enable differential use of the feeding habitat. This is only partial, however, and the results suggest that feeding habitat is not easily partitioned (horizontally) by means of differences in neck length. A more important function of neck length seems to be (2) the differential use of the feeding depth dimension in the same feeding habitat (i.e. vertically). (3) At the same feeding depth some differences in the use of food type can be achieved by means of differences in bill morphology. Distribution of species in the morphologically defined niche hyperspace and competition-based interpretations of the results are discussed.