Male chickens, Gallus gallus domesticus, give more aerial alarm calls in response to overhead hawk models in the presence of conspecifics than when they are alone. The specificity of this 'audience effect' on call production was investigated by placing cocks with females of three chicken strains. One strain was the same as that of the male, the second differed in plumage colour, and the third differed in plumage colour and texture, as well as in comb morphology. Despite this variation in visual characteristics, all of the strains were equally effective in potentiating male alarm calling. In contrast, the duration of courtship displays elicited by hens of the three strains differed significantly. The strongest response was evoked by hens of the male's own strain and the weakest by hens of strain most different in appearance. Hence, the cock's sensitivity to variation in the appearance of hens exhibits marked context dependence. The visual characteristics necessary for the social potentiation of alarm calling are more broadly defined than those that elicit courtship. This difference in specificity may be attributable to the division of attention between eliciting stimulus and audience during alarm calling, but not during courtship, when the male's attention is focused entirely on the hen. The immediate response required by aerial predators may also have selected for less specific audience recognition criteria than in other contexts, such as food calling, where male behaviour is more deliberate and responses to audiences are more discriminating.