An Ethological Analysis of Open-Field Behaviour in Ducks Anas platyrhynchos

Five experiments were conducted with ducklings to test various implications of a model which holds that open-field behaviour represents a compromise between predator evasion tactics and social re-establishment tendencies. Pretreatment with electric shock and the presence of a human in the testing situation both served to retard the onset of vocalization and movement in the open field. Birds maintained in social isolation and group-reared ducklings tested in the presence of a cage-mate also took longer to initiate activity in the open field. Food deprivation, as an independent means of varying general arousal, failed to have any effect on open-field vocalization or movement. The results are discussed in the context of a reinterpretation of open-field testing from an adaptive-ethological perspective.