Bird ringing and nest recording in Britain and Ireland in 2017

This is the 81st annual report of the British Trust for Ornithology’s Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data collected and processed in 2017. Demographic data contributed to several research studies during the year, including a review of the conservation status of Raven Corvus corax and the impacts of licensed control. This quantified the extent to which non-breeding birds could be removed without impacting overall population sustainability, as well as the data permitted, but noted that a better understanding of age-specific survival rates was required. Nest Record Scheme data contributed to a large-scale collaborative study investigating the impact that temperature and rainfall have on the timing of events throughout the annual cycles of 10 000 animal and plant species across different trophic levels. The results indicated that the speed of response was greatest at low trophic levels. Future changes under a range of emission scenarios were estimated; these results indicated that advances in timing would be greatest for primary consumers. A statistical method was developed, using nest record data, to quantify nest failure, taking into account uncertainties generated during data collection. The method was applied to Blackbird Turdus merula records to compare survival rates of nests in gardens with those in the wider countryside. Survival in suburban areas was found to be higher than in urban or rural areas, and nests survived better in wetter conditions across all habitats. In order to quantify any welfare impacts of capturing wild birds, we examined the frequency with which passerines were reported to have died either whilst in the net or during handling. Analyses of capture data submitted from 2005 to 2013 indicated that the average mortality rate is around 0.1%, and that this is consistent between years. Most fatalities occurred before individuals had been extracted from the nets and juveniles appeared to be at greater risk than adults. In 2017, 135 CE sites submitted data. Long-term (1984–2016) declines in abundance were observed in four migrant, one partial migrant and one resident species and concurrent increases in abundance continued to be recorded in two short-distance migrants and four resident species. There was no change to the 10 species which exhibited significant long-term declines in productivity; only one species, Chaffinch Fringilla coelebs, exhibited a significant long-ter