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. 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.
- If you wish to purchase a physical copy of a report please contact researchreports@bto.org.
- More information about our Annual Service reports to JNCC 1992-2005.
Assessment of recent Hen Harrier population trends in England through population modelling
This study uses a population modelling approach to explore the effects of changes in rates of productivity, survival, and settlement on population growth in the English population of Hen Harriers.
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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
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 reportOr, browse all editions of the Breeding Bird Survey Report >
15.05.25
Reports BBS Report
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
Reports Research reports
Description of the downy chicks of the Long-tailed Nightjar Caprimulgus climacurus
Author: Wetherhill, A.S., Dickson A. Matthew, D.A., Mayowa, E.S. & Izang, M.S.
Published: 2025
The Long-tailed Nightjar Caprimulgus climacurus is fairly common across its wide distribution in west and central Africa, south of the Sahel zone, but until this study, its downy chicks had been described only briefly.
22.04.25
Papers
Framework for assessing species vulnerability whilst on migration to a spatially explicit anthropogenic pressure
Author: Green, R.M.W., Cook, A.S.C.P., Burton, N.H.K., Franks, S.E. & Green, J.A.
Published: 2025
Migration is a critical component of animal lifecycles, and human development globally is increasingly interfering with animal migration routes. There is not a generally accepted approach to assess impacts of development on migratory species. This study showcases a framework to enable impacts to be assessed comparatively. It uses UK ducks, geese and swans as a case study to illustrate the variation between species.
17.04.25
Papers
