[1] It was founded in 1962 and is one of the largest county bird clubs in Great Britain with a membership of 1988 as at the end of financial year in December 2014.
Shortly after its formation in 1962, the Society took over publication of the Sussex Bird Report, first published in 1948 and previously edited by Grahame des Forges and Denzil Dean Harber.
In 2008 the SOS recorded the millionth bird in their database, a grey heron seen near Bognor Regis.
As the Society approached its 50th anniversary in 2012, it had 1695 members, membership at the financial year end of 2014 nearly 2000 making it one of the largest county bird clubs in Great Britain.
[3] Membership is by yearly subscription and includes a quarterly newsletter and a copy of the annual Sussex Bird Report.