Parent-offspring relationships have been studied much more than the relationships among siblings in precocial birds (those that are highly developed upon hatching). It is suggested that the attraction to siblings and unrelated peers in precocial birds is not of the same sort as the rapid attachment to a parental figure that has been called filial imprinting. The present experiments investigated the development of individual and species recognition and the significance of brood size in white Peking ducklings. The ducklings were reared singly or in pairs and they were tested under a simultaneous choice condition, across seven days of age, for a preference of (1) a peer (same-age duckling) versus an inanimate object (a pyramid), (2) a peer versus a different-species bird (a domestic chick) of the same age, (3) a single unfamiliar peer versus a conspecific brood of 10 ducklings, (4) a familiar peer versus an unfamiliar conspecific brood of 10, and (5) a familiar peer versus a brood of 10 chicks. The results were analyzed using a paired-samples t-test for each hypothesis stated and a trend analysis for age effects. The ducklings demonstrated a strong preference for (1) a peer over a pyramid, (2) a duckling over a chick, (3) a brood over a single pee , (4) a brood of ducklings over a familiar peer, with increasing attraction to the familiar peer over days, and (5) a familiar peer over a brood of chicks. These results indicate the importance of siblings and unrelated peers for white Peking ducklings. The significance of these results is discussed.