The avian neck system is an anatomically complex system. It comprises 12 (some finches) to 24 (swan) cervical
vertebrae, which are rotated by a large number of muscles (more than 200 in the chicken). In birds the neck
generates a variety of head trajectories and postures during many different behaviours (Zweers et al., 1994; Bout,
1997), e.g., during food acquisition and manipulation, head balancing, orientation, preening, perching, displays, etc.
The primary function of the cervical column is to position and orientate the head during all these kinds of
behaviour. The number of cervical vertebrae that are involved in generating the neck postures and movement is
always much larger than required from a kinematical point of view. The avian neck can be considered as a
kinematic redundant structure: there are far more degrees of freedom than necessary to position and orientate the
head. The analysis of underdetermined structures is especially interesting when investigating movement strategy
and movement coordination. Kinematically, the position and orientation of the head do not determine a unique
neck posture. This project proposes to test the minimal energy model for avian neck movement. For this project
direct recording of neck movement with highspeed X-ray video is available. This technique allows direct and
accurate measurements of joint angles during various neck movements. A model calculating the physical net
energy costs of neck movement has been developed in Leiden (The Netherlands), but has not been tested yet.
Kinematical data will be collected from two species, chicken (Gallus domesticus) and duck (Anas platyrhynchos),
and compared to data predicted by the model for the same head trajectory with respect to the body.