Potential Adélie penguin breeding habitat (defined as ice-free land with area >4000 m2 and within 500 m of the ocean) in the Australian Antarctic Territory (AAT) was mapped using a GIS, and the literature reviewed for evidence of the mapped habitat being searched for occupation by breeding Adélie penguins. The total area of potential breeding habitat was estimated to be close to 700 km2. Definitive or reasonably strong evidence of search effort was found for 63% of all potential habitat sites and 40% of the total potential habitat area. There were marked regional differences in search effort, and the majority of search effort occurred in the 1980s. Incomplete search effort is a possible source of negative bias for AAT-wide estimates of Adélie penguin breeding abundance derived from published search effort and count data.