Bird ringing in Britain and Ireland in 2004

This is the 68th annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2004. During the year, changes in bird survival in relation to winter weather were studied. In almost all cases, there was a greater influence of weather on first- year than adult survival. A paper providing guidelines to help those setting up demographic monitoring schemes for waders was produced, with ringing as a key component. Concern about a reduction in reporting rates of ringed birds led to a study of the changes. Declines were found across nearly all taxonomic groups and may reflect a combination of changes in reporting behaviour, ringing behaviour or bird behaviour. A study of the timing of muirburning used the ringing dates of pulli in conjunction with nest record data to assess its possible effect on breeding birds. There appears to be little reason for differences in cut-off dates for muirburning in different regions and at different altitudes, but further work is required to quantify more fully the effects on moorland birds. Data gathered as part of the Constant Effort Sites (CES) Scheme showed increases in the numbers of adults of several, mainly migrant, species, possibly as a result of high rainfall in Africa south of the Sahara. Productivity was good for most species. Cetti's Warbler Cettia cetti was added to the list of species covered and a study of habitat on CE sites showed that vegetation management mitigates the effect of habitat progression on catching rates. Data for 117 Retrapping Adults for Survival (RAS) studies were submitted. Over 12,000 Swallows Hirundo rustica were ringed as part of the Swallow Roost Project. The total number of birds ringed (881,920) was the highest ever, showing an 18% increase on the mean of the previous five years (1999-2003). The recovery total (11,930) also increased (by 9% compared to the mean of the previous five years). Recoveries of 154 BTO-ringed birds and 102 ringed abroad are presented in the report. They include records that confirm suspected or known migration patterns as well as the more unexpected movements.