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There is a need for effective and environmentally sensitive methods of controlling vertebrate pest problems in agriculture and the urban environment. Nonlethal chemical repellents may meet this need where more traditional methods of control, such as scaring, shooting, and trapping, are either ineffectual or unacceptable. One such chemical repellent currently under investigation is cinnarnamide, a synthetic compound derived from a plant secondary compound, cinnamic acid. Cinnamamide is unusual because, unlike many of its contemporaries, it deters feeding by both birds and mammals. This paper reviews past and current laboratory and field studies in which cinnamarnide is shown to deter feeding by problem birds, such as the woodpigeon (Columba palumbus), rock dove (C. livia), and chestnut-capped blackbird (Agelaius ruficapillus) , and mammalian pests, such as the Norway rat (Rattus norvegicus), house mouse (Mus musculus), and European rabbit (Oryctolagus cuniculus). Using peanuts in feeders as a model "crop," we also show that free-living birds (e. g . greenfinch [Carduela chloris], blue tit [Parus caeruleus], and great tit [P. major]) are prepared to incur an increased risk of predation or abandon a feeding site altogether in order to avoid eating food treated with cinnamamide. Laboratory studies of cinnarnamide's mode of action suggest that it has both primary (immediate) and secondary (postingestional) activity. Birds generally respond immediately to the compound through unpleasant effects mediated through taste, odor, or irritation of the buccal cavity, whereas some mammals do not find it instantly repellent but learn to avoid it because of its postingestional activity.