A population census of the three Adelie penguin colonies in the area of Cape Bird was carried out over several seasons since 1965, between November and December each year. These counts were conducted by ground based observations. Simultaneously, aerial photographs were taken by another study. The total number of birds was counted by 2 people using hand counters. The totals needed to be within 1% ... of each other or they were recounted. The final number for each colony was determined by averaging all the totals for that colony and rounding to the lower number. Occupied nests were counted with the same technique. Initial maps of the three main colonies were drawn from aerial photographs taken in the late 1960's. Copies of original maps were examined in the field and amendments were made to document changes in the colonies over the years and to update the information for future colony counts. Any penguin or McCormicks skua with bands were read while making the annual colonies count (penguin) or search for during the evenings (skua). The nest sites of skuas were mapped and band numbers of skuas using the nests were recorded in some years. A census of the penguin colonies at Cape Royds was conduction in 1959, 1975, 1977, 1979-1988 using the same methods.