Functional morphology of the hindlimb musculature of the black-billed magpie, Pica pica (Aves, Corvidae)

In spite of the ecological relevance of terrestrial locomotion for many bir d species, this function remains poorly studied to date. Gait preferences a nd transitions seem present, but it is not known which factors might determ ine the running style. Morphological and morphometric data needed for furth er biomechanical modelling are presented for the black-billed magpie (Pica pica), a species which walks, runs and hops. Detailed descriptions of the m uscle-tendon systems and the attachment sites on the hindlimb skeleton are given. Pinnation angles, fibre lengths and muscle masses are determined. Fr om the latter two, physiological cross-sections of the muscle bundles are c alculated. Tendon ossifications are qualitatively scored. Further, informat ion on the mechanical Variables of the body segments are collected (i.e. ma ss, length, position of the centre of gravity and moment of inertia of digi ts, tarsometatarsus, lower leg, upper leg, body, and head/neck). Moment arm s of the important muscles powering terrestrial locomotion are discussed an d, for some upper leg muscles, an equation to calculate the moment arms as a function of knee and hip joint angles is presented. All these data are in dispensable for further kinesiological research.