Le bec des oiseaux ou quand l'anatomiste et l'écoéthologiste ont besoin l'un de l'autre

Morphofunctional analyses of bird bill apparatus by anatomists are particularly important and fruitful when musculoskeletal data are compared with behavioural and ecological field data. These analyses, based on graphic analyses of static balance of forces (derived from common practices in building engineering and fundamental laws of mechanics), allow the production of functional hypotheses that can be falsified by eco-ethologists, and the formulation, and even expansion, of questions raised by eco-ethologists. The importance and necessity of constant exchanges between laboratory anatomists and field ecoethologists are illustrated by (1) the example of the Hoatzin which appears as possessing all the necessary attributes for rumination (i.e. equipment for cutting and ingesting large leaf parts that can be stored rapidly in the quite odd gut and which could be belched and kneaded in the peculiar buccal cavity before reingestion), (2) the example of Gabonese equatorial forest Flycatchers whose habitat selection can be better understood through the morphofunctional analysis of their bill apparatus, and (3) the example of the Hoatzin, Cuckoos and Turacos which allows the elaboration of an evolutionary biomechanical pathway completely different from that followed by Galliformes.