Morphologie bucco-linguale d'une guilde de canards barboteurs

Abstract

Interspecific variations of bucco-lingual characteristics were measured in a guild of dabbling ducks and the influence of these characteristics on the use of food resources was studied. Morphological characters of the bill and tongue were measured in eight species of dabbling ducks of the genus Anas. Our results show that there are interspecific differences in the bucco-lingual characteristics of all species studied except for the Black Duck (Anas rubripes) and the Mallard (Anas platyrhynchos). There was a significant correlation between the density of bill lamellae and the weight of the species (r = −0.935, P < 0.01). In six species, the density of the lamellae was correlated with the volumetric index of the bill (r = −0.960, P < 0.01). These results indicate that in species with large bills the density of the lamellae is low, whereas in species with small bills, the number of lamellae is high. The volumetric index of the bill was significantly related to the average weight of each duck species (r = −0.905, P < 0.01). Dabbling ducks that filter benthic material can thus be classified on a scale based on lamellar density and bill volume. The differences in bucco-lingual morphlogical characters seem to reflect a mode of resource partitioning that diminishes competition.[Journal translation]