The Army Ornithological Society (AOS) members provide the Army's focal point for ornithological issues by getting involved in conservation work, bird counts and other Ministry of Defence (MOD) and civilian schemes through field trips, overseas expeditions and scientific studies.

Past expeditions have visited Ascension Island, as well as foreign countries: Belize, Canada, Croatia, Ecuador, Ethiopia, Holland, Nepal, Spain, Thailand and The Gambia. Membership is open to serving and ex-Army personnel, other Services and their families, MOD-employed civil servants and members of Commonwealth Forces. Contributing to the British Trust for Ornithology’s national bird atlas was just one small part of activities and, whether just starting out or with a detailed knowledge of birds, the Society welcomes all to its ranks and makes a point of developing interest through practical field activities.

British military ornithological societies have monitored the colony of sooty terns and other seabirds on Ascension Island in the South Atlantic since 1987. The first population census was completed in 1990 ten years prior to the commencement of the RSPB-led cat eradication on the Island. Sooty terns were monitored closely during the two years when cats were culled, and now AOS continue the monitoring in the post-eradication phase. Several reports and scientific papers have been published using the results of the surveys.