Some observations on pecking in pigeons.

An attempt was made to analyse the pecking behaviour in pigeons induced by apomorphine. The pecking was completely suppressed by tranquillizers, barbiturates and cortisone. It was intensified by histamine, nicotine, lobeline, testosterone, progesterone and sodium taurocholate. None of the drugs tested could induce in pigeons pecking typical of apomorphine. Apomorphine induced pecking in other birds too. It was concluded that the pecking phenomenon after apomorphine is similar to the natural feeding movements performed by pigeons while eating grains and possibly it is the function of a specialized area in the limbic system of the brain which is stimulated by apomorphine.