Bird ringing and nest recording in Britain and Ireland in 2021

ABSTRACT

This is the 85^th 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 processed in 2021. In 2021, 105 Constant Effort Sites submitted data for the year. Long-term (1984–2020) declines in abundance were observed for five migrant, one partial migrant and five resident species, while long-term increases in abundance were recorded for two short-distance migrants and seven resident species. Ten species are exhibiting significant long-term declines in productivity, while only Chaffinch Fringilla coelebs shows a significant long-term increase. Long-term trends in survival indicate increases for 12 species and declines for seven. Short-term trends, which compare the current year to the five-year mean for 2016–20, show that the abundance of seven species increased significantly in 2021, with one species, Treecreeper Certhia familiaris, being recorded in higher numbers than in any previous year of CES monitoring. Significant decreases in abundance were recorded for four species. Productivity decreased significantly for seven migrant and 11 resident species in 2021, with six species recording their lowest breeding success since CES monitoring began; no species recorded a significant short-term increase. Significant changes in survival rate were observed for two species in 2021 compared to the five-year mean, with Song Thrush Turdus philomelos increasing and Chaffinch both declining and recording its lowest survival rate ever. The Garden CES trial continued in 2021, with 60 sites submitting data. The new winter ringing project also continued in 2021, with submissions received from 126 sites. The number of Retrapping Adults for Survival projects that were able to run and submit data in 2021 was 192, with data from one more project submitted too late to be included in this report and another four active projects unable to operate. In total, 60 species were monitored, with Starling Sturnus vulgaris (21 projects), House Sparrow Passer domesticus (20 projects), Pied Flycatcher Ficedula hypoleuca (19 projects), Reed Warbler Acrocephalus scirpaceus (nine projects) and Sand Martin Riparia riparia (nine projects) the species most studied. A total of 900 131 birds were ringed during the year, comprising 146 458 nestlings, 438 342 first-year birds, 291 127 adults (birds in their second calendar year or older) and 24 204 birds whose age could not be determined. In addition, there were 210 147 recaptures of ringed birds at or near the ringing site. In total, 42 328 recoveries (birds found dead, recaptured or resighted at least 5 km from the place of ringing) of BTO-ringed birds were reported in 2021. The Appendix highlights a selection of recoveries that have extended our knowledge of movements, as well as longevity records established during the year. A total of 41 096 NRS submissions were received in 2021. Mean laying dates for 2021 were significantly later than the average for 13 species and only one species significantly advanced its laying date. Five species displayed a significant change in fledglings per breeding attempt, with two recording increased productivity and three reduced productivity. Permits or licences to disturb breeding birds on Schedule 1 of the Wildlife and Countryside Act 1981 (as amended) were prepared and issued to 602 ringers and nest recorders in 2021. During 2021, 2588 marking endorsements, 868 sampling endorsements and 214 trapping endorsements were issued in the UK and overseas.

Acknowledgements

The work of the Ringing and Nest Record Schemes contributes to a programme of research undertaken in a partnership between BTO and JNCC (on behalf of NE, NRW, NatureScot and DAERA). We thank staff at JNCC and in the Country Agencies’ Licensing Teams who support the partnership and offer timely advice when needed.

The Trustees of the Natural History Museum continue to allow their internationally recognisable address to be used on bird rings. Their staff receive and pass on many reports of ringed birds each year and we are very grateful for their cooperation and support for the Ringing Scheme. Ringing schemes across the world work together to ensure that ringing continues to be international, and we are grateful to be a part of this collaboration.

Porzana Ltd has supplied BTO rings since 2001 and we thank their staff for continually providing excellent rings in a timely fashion.

The following volunteers helped with office tasks (either at BTO HQ or remotely) in 2021. We are extremely grateful for their valuable help:Ringing Scheme: John Bonell (ringing data inputting) and Dorian Moss (EURING Data Bank).Nest Record Scheme: Andrew Bevan, John Bonell, Daniel Jenkins-Jones, Nigel Judson, Michael Wraight.

Despite the launch of DemOn in 2017, many ringers continue to use IPMR. The work of Mark Cubitt in creating and maintaining IPMR has been invaluable to both the Ringing and Nest Record Schemes and we continue to be very grateful to him and the software advisors for their ongoing help for ringers using the software.

Hazel McCambridge, Anne Trewhitt and Diane Bragg provided clerical and secretarial support. Graham Appleton, Carl Mitchell and Mike Toms improved this report with their comments.

We extend our gratitude to all landowners and land managers who generously allow ringers and nest recorders to operate on their land. Without this cooperation, our volunteers would not be able to collect the data that we rely on. Every member of the public who finds and takes the time to report ringed birds to us is helping us to improve our ability to track bird populations and for this we are very grateful.

Finally, we thank everyone who has participated in, or promoted the schemes in any way during 2021. We would not be able to generate the results shown in this report if it weren’t for ringers and nest recorders being willing to expend their time, effort and own money to collect the data. Our thanks also go to those who contributed to articles in LifeCycle and elsewhere that have helped to promote the schemes; your projects and stories are invaluable in helping to publicise the schemes and the work we all do.

Notes

1 Detailed analysis of the drivers behind changes to species monitored through CES can be found in previous reports (e.g. Walker et al 2016) and on the BirdTrends pages of the BTO website (bto.org/birdtrends). The long-term trends are published in the BTO BirdTrends report (Massimino et al 2023).