Finnish Museum of Natural History
Constant Effort Ringing in Finland
The Constant Effort Sites (CES) ringing programme, aimed at net ringers, uses catches from standardised mist-netting to monitor our most common breeding songbirds. The CES provides a measure for the changes in population size of abundant CES species, and supplements the view given by line transects and point counts. It also provides valuable information about breeding success after the nestling stage. Other monitoring programmes do not measure this. In addition, retraps from adult birds can be used in estimating mortality. The project started in 1986.
In practice, CES works like this: the ringer erects the standard number of nets, in standard positions, all chosen by himself, on twelve days evenly spread between early May and late August. Everyone can choose, according to own choice, the capture routines, which however, should be followed from one year to the next.
The CES concept was brought as such from Great Britain to Finland. The Constant Effort Sites was started in Great Britain in 1981, and today birds are ringed there at more than 130 catch sites within this programme. In addition to the Finnish programme, similar capture programmes have been started in France, the Netherlands and Sweden. The corresponding North American MAPS monitoring study already includes more than 400 catch sites. It is the goal of EURING to expand CES so that it would cover all of Europe. In 2005, CES was running at 28 sites in Finland. The catch sites were situated in 25 different municipalities, and 44 ringers took part in this project.