A number of animal species are known to travel in organized formations, such as fish schools and the V-shaped formations of migrating geese. It is believed that moving in such formation may allow energy conservation during swimming or flying. This would benefit individual animals in the group by allowing them to travel at higher speeds or over longer distances than if they traveled alone. A similar situation is observed for human cyclists or race cars which use a technique called "drafting" to increase fuel economy and overall speed. Past attempts to measure such benefits for animal formations have met with limited success, because the size and complexity of animal formations has prevented researchers from directly measuring any energy economy derived from formation travel. This project will attempt to measure energy economy by formation swimming in mallard ducklings. The advantages of studying ducklings are that ducklings swim in a simple, straight line formation, and the formation is small enough to be easily studied in the laboratory. Groups of imprinted ducklings will be trained to swim at various speeds in a water channel while following a decoy. Comparisons of energy expenditure per animal will be made by manipulating group size, presence or absence of decoy, and age of ducklings. The metabolic rate, measured from oxygen consumption, will indicate any energy economy by swimming in formation. Simultaneously, video recordings will be made to detail the paddling motions of the ducklings. Analysis of these motions can be used with a hydrodynamic model to compute the energy expended during swimming and to determine if particular positions in a formation provide energy economy. In addition, experiments will be conducted in which a dye injected into the water around the ducklings will show the pattern of water flow. This can provide insight into the physical causes for increased energy economy. The results of this study will provide empirical data as to the extent of energy that can be saved as animals move in formation.
