Meeting Abstract

75.6  Wednesday, Jan. 6   Metabolic energy cost of locomotion over uneven terrain in the common pheasant (Phasianus colchicus). DALEY, MA*; FISHER, RL; GILES, T; WARNER, S; Royal Veterinary College mdaley@rvc.ac.uk

It has been proposed that a trade-off exists between economy and stability of legged locomotion. However, it is unclear whether this is generally true, because little research exists on the relationship between stability and metabolic energy cost of locomotion. If such a trade-off does exist, animals might adopt different movement strategies when running over uniform versus uneven terrain. To test this idea, we have measured kinematics and metabolic cost energy cost of locomotion in five pheasants (Phasianus colchicus) as they ran on an obstacle treadmill. We measured terrains with obstacles at 10, 20, 30 and 40% leg length, with fixed height obstacles at approximately every fifth step. We used open-circuit respirometry with Nitrogen dilution calibration to measure metabolic energy consumption. From kinematics it appears that 60% of the movement strategy can be explained by the birds adopting a more crouched posture to minimise changes in body height over the obstacle. For highest obstacle conditions, there is evidence that the birds increase their body height in anticipation of an upcoming obstacle, whereas in the smaller obstacle conditions, there is little evidence of anticipation. Oxygen consumption increased approximately linearly with obstacle height for the 10-30% leg length obstacle conditions. Surprisingly, there is a sharp reduction in oxygen consumption at the 40% leg length condition. This discontinuity suggests that the birds switch to a different locomotor strategy for highest obstacle heights, and may also suggest that the birds are not optimising their movement strategy for economy at the lower obstacle heights (supported by a Royal Society Research Grant to MAD).