Mate recognition of adelie penguins is crucial to their breeding success in such an extreme environment. The importance of male ecstatic display, the role of factors including nest location and size and the individual mating history in Adelie penguin mate attraction and pair bonding was investigated at three sub-colonies in the Cape Bird colony. The role of female choice and competition was also ... investigated. At Cape Bird (North, Middle and South colonies) a random sample of male ecstatic display calls were recorded and analysed. Males were weighed and sex was confirmed genetically by pulled feathers. In addition to calls, other information that was noted include GPS location of the male in the colony, location of the nest (center or edge), presence of a partner at the nest and a measure of breeding status (presence of eggs in nest/number of chicks). Measurements and recordings were collected at the beginning of the pair bond stage and at the end of the guard stage in order to assess the potential change in Ecstatic call components over the season due to changes in body condition. A chick condition index (randomly selecting chicks and weighing them and measuring their flipper length) to assess colonies breeding success. To determine the effects of condition on call parameters, mate choice and ultimately breeding success, a focal sub-colony from the Northern colony was observed. During the initial pair bond phase, a random selection of males from the centre, middle and edge of the colony had their ecstatic display recorded, nest position marked, diameter and circumference of the nest measured and weight recorded. The focal male was observed for frequency of Ecstatics, number of approaches by prospecting females, number of copulations (complete or incomplete) and any incidences of female-female competition over a focal male. In addition, the day of arrival of the male into the colony and the date that final pairing was achieved, the first and second egg laying date and predicted hatch date were recorded. At the same site, the movement of females was followed from arrival into the sub-colony through to initial pairing and when it occurred, pair swapping until final pairing was achieved. The males of these females were recorded for call, weight, nest size and location. At the end of the guard stage, the males were re-weighed and their calls recorded.