Aggressive behavior in immature ducklings.

Abstract

When a 5-day-old duckling is enforcibly exposed to a novel moving object, it gradually forms a filial attachment to it. The present research documented 3 behavioral stages that transpire during such socialization: (a) The duckling initially attempts to escape, (b) the tendency to escape wanes and aggression toward the object emerges, and (c) aggressive behavior wanes and filial behavior becomes evident. Additional experiments illustrated how the presence and absence of a previously imprinted stimulus controlled aggression and the necessity of enforcing proximity between the subject and the novel object in order to obtain aggression. By doing so, these experiments provide support for the hypothesis that this aggression is fear mediated and that a low but nonzero level of fear maximizes its occurrence.

Distress calling induced by reductions in group size in ducklings reared with conspecifics or imprinting stimuli

“…Both are characterized by a relatively brief sensitive period during the first few days after hatching (Hess, 1973;Lorenz, 1935;Ramsey & Hess, 1954). If a young bird is socially isolated during this period, then the bird will typically flee and give distress calls when either a sibling or an imprinting stimulus is presented, rather than following and giving calls of contentment (Hoffman, Ratner, Eiserer, & Grossman, 1974). Furthermore, ducklings will learn an operant response to gain access to either a sibling or an imprinting stimulus (Bateson & Reese, 1969;Gaioni, Hoffman, DePaulo, & Stratton, 1978;Peterson, 1960), and in both cases the pattern of responding is quite similar, with responses occurring in bursts, rather than at a steady rate (Gaioni et al, 1978;Hoffman & Kozma, 1967).…”

The effects of tactile stimulation on imprinting in ducklings after the sensitive period

“…Little or no aggressive behavior-in the form of pecking directed towards the imprinting objectwas observed in the present study, even though such aggression might have been expected to occur (Hoffman, Ratner, Eiserer, & Grossman, 1974). However, in the visual-only condition, the stimulus was kept 6 in.…”

Mediating factors in chick social pecking: II. effects of exposure to movement

“…First, isolation and separation are known to produce negative emotional reactions in precocial hatchlings [Rajecki, Suomi et al, 19771 and do lead to aggressive responses in these birds (eg, Hoffman et al, 1974;Rajecki et al, 19761 . Second, the provision of an imprinting object that is accessible to the isolate drastically reduces conspecific aggression, even though the imprinting object bears very little resemblance to the isolate's species-mates [Hoffman et al, 1975;Rajecki et al, 19781. Since chicks reared in pairs show none of the day-to-day emotionality evidenced by isolates [see Rajecki, Suomi et al, 19771 , it seems reasonable that hatchlings reared with a surrogate would be less upset than hatchlings reared alone. Finally, the provision of a visible, animated object that cannot be approached (Experiment 2, above) does not reduce conspecific aggression, probably because the repeated frustration of approach attempts causes an adverse and chronic emotional reaction in chicks.…”

“…Aggressive behavior is elicited by movement in mammals [mice: Lagerspetz and Portin, 1968, Cairns and Scholz, 1973, Connor and Lynds, 1977rats: Albert andGalef, 1973, Blanchard et al, 1975;and rabbits: Mykytowycz and Hesterman, 19751 and fish [Betta splendens, Thompson, 19631 , hence information on birds is important to the comparative psychology 0096-140X/78/0404-0331$02.60 0 1978 Alan R. Liss, Inc. of aggression. Furthermore, several recent reports [Hoffman et al, 1975;Rajecki et al, 19781 suggest that experience with figure-ground movement of artificial or nonconspecific objects during social isolation may limit aggression when ducklings and chicks are exposed to live testmates.…”