SCALING OF SKELETAL ELEMENT MASS IN BIRDS

The dry mass from different skeletal elements of 63 specimens belongin g to 49 species of birds was measured. The body mass range was 5.7 g-9 8 kg. Correlations of the mass of the skeletal elements to body mass w ere established by means of Model II of regression. Positive allometry was found in the case of the femur, tibiotarsus-fibula, tarsometatars us, synsacrum and thoracic vertebrae, while the skull and sternum show ed negative allometry. For a given body mass, a larger mass of avian h umerus, ulna-radius and tibiotarsus-fibula can be expected, in compari son with the corresponding bones in mammals. Finally, some species dis played special values for some of their skeletal elements. For example , two orders (Galliformes and Columbiformes) displayed a tendency to l ighter skeletal structures.