The vocal communication of Adelie penguins at Cape Bird was investigated. A single colony was selected from the Northern colony for study and all birds (established breeders and most of the non breeders) were banded to observe their behaviour and to recoginze the day to day changes of their roles in incubation or guarding. The colony was mapped and monitored during the season. In the late stage of ... chick creche formation, parent penguins call their chicks by Loud Mutual Vocalization (LMV) at a distance from the colony when they return from foraging and feed their chicks outside the colony. During crech formation, 8 adult calling voices were recorded. Study of the LMV by soundspectrograph found the vocalisation was divided into three parts A, B and C. Experimental tapes were made to include series of individual voices, including: a) live voice, b) repetition of the one typical LMV, c) repetition of part A, d) repetition of part B and e) repetition of part C. Calls were replayed outside the colony and the response of the chick to the calls was recorded by 16mm and 35mm cameras.