BTO Research Reports

BTO Research Reports

BTO Research Reports are scientific papers that have been self-published by the BTO. The following is a full list of the published BTO research reports, which includes BBS reports, Waterbirds in the UK (WeBS) reports and SMP reports. Most are free to download, and links to Abstracts are included where possible.

Numbers missing from the list are those allocated but which were never produced or which have not been published. BTO recognises that, particularly in respect of commercially sensitive cases, a period of confidentiality is appropriate for some projects. However, in the interests of scientific development and dissemination of information, we encourage clients to permit publication as soon as it is reasonable to do so.

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BTO Northern Ireland Marine Bird Evidence Review 2024: marine bird spatial use in the Celtic Seas

Author: Hereward, H.F.R., El Haddad, H., Humphreys, E.M., Taylor, R.C. & Upton, A.J.

Published: 2025

This report was commissioned by the Northern Ireland Environment Agency to scope the evidence available on the movements and spatial distributions of certain marine birds in and around Northern Ireland waters, in order to identify knowledge gaps. The focus is on 37 marine birds found offshore, away from the coastline, that utilise the Celtic Seas (OSPAR Region III) and Ireland Exclusive Economic Zone marine environments. Metadata from 10 different sources (including directly contacting researchers, a literature review and accessing several archived datasets) are used.

07.07.25

BTO Research Reports

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Efficacy of methods for producing population trends of breeding waders from Breeding Bird Survey data

Author: Brighton, C.H., Gillings, S. & Massimino, D.

Published: 2025

This report investigates the efficacy of methods for producing population trends from BTO/JNCC/RSPB Breeding Bird Survey data for six breeding wader species in the UK. It examines the effects of increasing the count threshold on the population trends for these six species, and also explores the effects of different geographic exclusion rules on the population trend of Golden Plover. Overall, it aims to test for any potential biases in the current trends, and in doing so, determines whether we can create a better approach which provides the most robust data for wader conservation moving forwards.

23.06.25

BTO Research Reports

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Review of methods used to calculate scale of artificial nesting structures proposed as a compensation measure for Kittiwake mortality at offshore wind farms

Author: Rhoades, J., Johnston, D.T., Humphreys, E.M. & Boersch-Supan, P.H.

Published: 2025

This report reviews the suitability of methods used to calculate the scale of Artificial Nest Structures (ANS) provided as compensation measures for Kittiwake mortality at offshore wind farms in English waters, due to turbine collision only. This report was revised in October 2025 and republished on 30-10-2025, correcting an error in Table 5. The recalculated compensation populations in the original report did not match the underlying fecundity values in the column headers. In addition, a link to helpful computer code was added to Appendix 3 (see below).

19.06.25

BTO Research Reports

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Waterbirds in the UK 2023/24

Author: Calbrade, N.A., Birtles, G.A., Woodward, I.D., Feather, A., Hiza, B.M., Caulfield, E.B., Balmer, D.E., Peck, K., Wotton, S.R., Shaw, J.M. & Frost, T.M.

Published: 2025

The report provides a single, comprehensive source of information on the current status and distribution of waterbirds in the UK for those interested in the conservation of the populations of these species and the wetland sites they use. Key stories from this report include more updates on avian influenza affecting migratory Barnacle Goose and Mute Swan, as well as a focus on the latest WeBS Alerts, looking at how wintering waterbirds are doing in protected areas. View the press release for this report

22.05.25

Reports Waterbirds in the UK

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The Breeding Bird Survey 2024

Author: Heywood, J.J.N., Massimino, D., Baker, L., Balmer, D.E., Brighton, C.H., Gillings, S., Kelly, L., Noble, D.G., Pearce-Higgins, J.W., White, D.M., Woodcock, P., Workman, E. & Wotton, S.

Published: Spring 2025

These are the main schemes for monitoring the population changes of the UK’s widespread breeding birds, providing an important indicator of the health of the countryside. The results are published annually as Official Statistics and used widely by Defra and the Statutory Nature Conservation Bodies (SNCBs, e.g. Natural England and NatureScot) to set priorities and to inform conservation action, and as the evidence base against which the UK’s biodiversity targets are measured. BBS data are also routinely used in research, with recent examples including peer-reviewed papers published in 2022 and 2024 which measured the efficacy of the UK’s network of protected areas in supporting wildlife. The 2024 Breeding Bird Survey Report highlights the continuing decline of some farmland species and more recent declines of woodland birds, at least in England. In Scotland, there is a focus on upland birds, where an all-species indicator using BBS data shows a 20% decline since 1994. In Wales, there are mixed fortunes, with species like House Sparrow bucking the downward trend seen in England, whilst Curlew are in severe decline, as they are elsewhere in the UK. Some songbirds in Northern Ireland, such as Blackbird are doing comparatively well compared to the wider UK trend. We thank nearly 3,000 skilled and dedicated volunteers who give their time to BBS and WBBS and make the monitoring of the UK’s breeding birds possible. Download the 2024 report Or, browse all editions of the Breeding Bird Survey Report >

15.05.25

Reports BBS Report

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Scientific support to the trial of Spoor AI at the European Offshore Wind Deployment Centre

Author: Brighton, C.H., Clarke, J.A. & Boersch-Supan, P.H.

Published: 2025

This report assesses the capability of a Spoor AI camera system with both mono-vision (single-camera) and stereo-vision capabilities for bird monitoring deployed at the European Offshore Wind Deployment Centre in Aberdeen Bay using both theoretical considerations and onshore and offshore field trials.

25.04.25

BTO Research Reports

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A review of existing methods to collect data on seabird flight height distributions and their use in offshore wind farm impact assessments

Author: Feather, A.P., Burton, N.H.K., Johnston, D.T. & Boersch-Supan, P.H.

Published: 2025

This document presents a review of existing methods for collecting seabird flight height data and their potential to produce flight height distributions that might be used in CRMs. The strengths, weaknesses, and limitations of different methods are identified and sources of measurement and sampling error, uncertainty and bias assessed. Best practice recommendations are provided for prominent methods and how data might be best utilised to inform stakeholders is considered.

15.04.25

BTO Research Reports

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