Bird ringing in Britain and Ireland in 2008

Abstract

This is the 72nd annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2008. Research carried out in 2008 included developing methods to combine ringing data with data from other monitoring schemes to detect the causes of population change. This approach was used for Song Thrush Turdus philomelos data, confirming the findings of previous analyses that the population decline observed over the last thirty years is primarily related to first‐year survival. Constant Effort Site data suggested that low productivity in 2007 contributed to reduced adult numbers during 2008 for many species, including significant decreases in Blackcap Sylvia atricapilla, Willow Warbler Phylloscopus trochilus, Blue Tit Cyanistes caeruleus and Bullfinch Pyrrhula pyrrhula. However, there were significant increases in numbers of adult Long‐tailed Tits Aegithalos caudatus and Chiffchaffs Phylloscopus collybita. As in 2007, the 2008 breeding season was poor, with 11 of the 25 core species monitored by the Scheme showing significantly lower productivity compared to the long‐term average (1983–2007). In contrast to 2007, many of the species faring worst were residents, including Blackbird Turdus merula, Song Thrush and Great Tit Parus major. Data for 92 Retrapping Adults for Survival studies were submitted, covering 34 species, more than half of which are of conservation concern. The total number of birds ringed (835,326) was 2% lower than the mean of the previous five years. This reduction may have been influenced by the poor breeding season in 2008; the total number of pulli ringed in 2008 (161,846) was 6% lower than the preceding five‐year mean, while that of fully grown birds (673,480) showed no change. The recovery total (15,164) was the highest in over 15 years; however, this is partly due to changes in the way that records of colour‐ringed and other specially marked birds are stored, which led to an inflation of the 2008 total. The number of recoveries of foreign‐ringed birds (1,192) was higher than the mean of the preceding five years, although this figure is influenced by response times of different ringing schemes, which vary from year to year. Recoveries of 230 individual birds are presented in the final section of the report. They include unexpected movements, movements that confirm suspected or known migration patterns, and longevity records.