This data set represents the accumulation of 19 years of seabird population abundance data collected by the Antarctic Site Inventory, an opportunistic vessel-based monitoring program surveying the Antarctic Peninsula and associated sub-Antarctic Islands. This Data Paper, which includes 1124 records from 113 locations for seven species of seabirds (Adélie Penguin [Pygoscelis adeliae], Gentoo Penguin [P. papua], Chinstrap Penguin [P. antarctica], Macaroni Penguin [Eudyptes chrysolophus], Blue-eyed Shag [Phalacrocorax atriceps], Kelp Gull [Larus dominicanus], and Southern Giant Petrel [Macronectes giganteus]), includes data already published by the Antarctic Site Inventory as well as seven years of recent data not previously published. Census data represent a mix of nest and chick counts; each census record includes the location, date, and precision of the census count, along with any auxiliary notes. Included with the database are maps to clarify the location of specific breeding populations that may be new (and thus not previously reported) or ambiguous. This compilation represents the best single source of raw data on the spatiotemporal dynamics of the Pygoscelis penguins in the Antarctic Peninsula region and provides population data on several flying bird species less frequently studied.