Electrical stimulation of the brain of unanesthetized, freely moving adult Mallard ducks (Anas platyrhynchos) produced response patterns characteristic of the aggressive and escape behaviors of this species. Aggressive reactions were classified into three categories: (a) directed attacks on a companion; (b) defensive threat display automatisms characteristic of a cornered bird but lacking attack behaviors; and (c) the rabrab and inciting vocalizations associated with aggressive encounters but unaccompanied by other responses associated with attack or escape. Five categories of fear-like reactions were distinguished: (a) sneak-into-cover reactions characterized by attempts to hide under objects and a strong preference for shelter; (b) crouch-flat reactions in which the birds would stretch out flat on the floor or surface of the water; (c) directed escape reactions characterized by a variety of response topographies but all oriented toward the window or shelter; (d) undirected escape reactions characterized by rushing or flying responses but lacking orientation; and (e) alarm vocalizations unaccompanied by other fear-like responses. Testing of the stimulation-produced reactions under a variety of environmental conditions indicated that many of the reactions (e.g., directed attack, sneak-into-cover) were dependent on specific stimuli for their performance, while other reactions (e.g., threat display automatisms) showed consistent thresholds and response topographies in a variety of situations. Aggressive reactions were elicited from the archistriatum and from wide areas in the diencephalon. Sites producing escape reactions were located primarily in diencephalic and midbrain regions. Evidence was presented suggesting that the different patterns of escape behaviors have different neuroanatomical distributions. © 1969, Brill. All rights reserved.
