The Constant Effort Sites (CES) scheme is the first national standardised ringing programme within the BTO Ringing Scheme and has been running since 1983. Ringers operate the same nets in the same locations over the same time period at regular intervals through the breeding season at over 140 sites throughout Britain and Ireland.
The Scheme provides valuable trend information on abundance of adults and juveniles, productivity and also adult survival rates for 24 species of common songbird.
The Constant Effort Sites Scheme is supported by a partnership between the British Trust for Ornithology (BTO) and the Joint Nature Conservation Committee (JNCC) (on behalf of: The Department of the Environment Northern Ireland, Natural England, Natural Resources Wales and Scottish Natural Heritage). It is also part of the BTO Ringing Scheme which is funded by the BTO/JNCC Partnership, The National Parks and Wildlife Service (Ireland) and the ringers themselves.