The effect of hunger on the exploratory behaviour of shoals of mosquitofish 'Gambusia holbrooki'

The question of how hunger affects locomotory behaviour, in particular how it affects the kinematics of movement and an animal's interaction with the physical structures in its environment is of broad relevance in behavioural ecology. We experimentally manipulated the hunger levels of individual mosquitofish ('Gambusia holbrooki') and recorded their swimming behaviour in shoals of 4 fish. We found that hungry individuals in shoals moved at greater speeds and had higher turning speeds than satiated individuals in shoals, as well as a greater variance in speed and turning speeds. We also found that hungry individuals explored more of the arena and used more of its internal space, away from the square arena's walls and displayed less wall-following behaviour than satiated individuals. A functional explanation for this change in swimming behaviour and interaction with environmental heterogeneity is discussed in the context of social foraging, as is the consequence of these results for models of search patterns and collective movement.