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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Trialling farmer wader counts and bioacoustics to aid agri-environment scheme evaluation

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Published: 2026

The primary tool by which wader conservation is delivered in farmed landscapes is agri-environment schemes, whereby payments incentivise land managers to conduct beneficial management for species or habitats. Assessments of the effectiveness of such schemes have been based on infrequent, large-scale surveys which do not produce landscape- or intervention-specific evidence to facilitate local adaptations to the design of agri-environment schemes. This report details work carried out at 10 participating farms in the Yorkshire Dales National Park, where we trialled two methods that could help to evaluate the effectiveness of scheme measures at regional scales.

27.03.26

BTO Research Reports

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Connecting Constable and Gainsborough Country: baselining for landscape recovery using multi-taxa passive acoustic monitoring

Author:

Published: 2026

Connecting Constable and Gainsborough Country is a DEFRA-funded Landscape Recovery project. This report describes the use of passive acoustic monitoring to assess the status and distribution of birds, bats, terrestrial small mammals, and bush-crickets across the Stour, Brett, and Box valleys in south Suffolk. The project supports habitat restoration and woodland connectivity, with a focus on rare or declining species of conservation concern, including the Hazel Dormouse, informed by robust monitoring.

25.03.26

BTO Research Reports

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Wild Neroche a multi-taxa, baseline passive acoustic monitoring survey 2025

Author:

Published: 2026

This report summarises results from the first year of Passive Acoustic Monitoring undertaken at Wild Neroche during spring and summer 2025. The intention is to establish a baseline dataset that will inform future assessments of how active management influences biodiversity across the Neroche area. This report summarises results from the first year of Passive Acoustic Monitoring undertaken at Wild Neroche during spring and summer 2025. Wild Neroche is one of four of Forestry England’s Wilder Forests, and is located in south-west England.The intention is to establish a baseline dataset that will inform future assessments of how active management influences biodiversity across the Neroche area. Bird communities were surveyed at 10 sites using autonomous recording devices operating in the audible range. During the initial deployment period, audible recordings were collected continuously during both day and night. The same devices were also operated in ultrasonic mode at nine of these sites to monitor bats, small mammals, and bush-crickets; ultrasonic recordings were restricted to night-time only. Audible recordings were collected on 140 days between April and September, while ultrasonic recordings were obtained on 67 nights between June and August. Devices were placed to survey a range of habitats including mixed deciduous woodland, coniferous woodland, heathland, and mesotrophic grassland. Analysis of ultrasonic data identified 13 species of bat, including the regionally important Barbastelle (Barbastella barbastellus) and Bechstein’s Bat (Myotis bechsteinii), both of which are included on the red list of British Mammals. In addition, three terrestrial small mammal species, four bush-cricket species, and two audible moth species were confirmed. One standout result of the ultrasonic survey was the exceptional number of detections of Hazel Dormouse (Muscardinus avellanarius), with 4,418 triggered recordings across six sites. Dormouse acoustic activity peaked in late July. In total, 73 species of birds were confirmed, including 35 species listed as Amber or Red on the UK Birds of Conservation Concern list. The repeated detection of Goshawk (Astur gentilis) across the survey area is also of particular interest.

09.03.26

BTO Research Reports

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Assessment of non-breeding Hen Harrier records in relation to Special Protection Areas in England: insights from the Hen Harrier Winter Roost Survey and BirdTrack

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Published: Winter 2025

This study uses Hen Harrier records from the Hen Harrier Winter Roost Survey and BirdTrack to explore the distribution of wintering Hen Harriers in relation to the distribution of Special Protection Areas (SPAs). There is a particular need to enhance survey effort in and around SPAs, to improve our understanding of the distribution and habitat use of non-breeding Hen Harriers in England, and to evaluate whether there is a need for site protection to be extended to more areas.

10.12.25

BTO Research Reports

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Evaluating aerial LiDAR and other approaches to avian flight height measurement – ReSCUE Project Validation Study Report

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Published: 2025

This report investigates the accuracy and reliability of seabird flight height data that are used to mitigate impacts of offshore wind farms on seabird populations. Through a set of trials, we set out to validate Light Detection and Ranging (LiDAR)-coupled Digital Aerial Surveys (DAS), and to a lesser extent size-based methods. Additional technologies evaluated in the trials included bird-borne Global Positioning System (GPS) telemetry tags and human-operated laser rangefinders. We found that the comparative performance of the two LiDAR-coupled Digital Aerial Survey suppliers varied based on system differences and weather conditions during surveys, particularly in terms of detection rates from different sensors. LiDAR flight height measurements, however, proved to be accurate and precise for both suppliers, with measurement uncertainties on the scale of centimetres. In contrast, size-based DAS estimates had uncertainties on the order of tens of metres. Findings from this study will directly inform the development of best practice guidance for seabird flight height data collection and analysis, supporting impact assessments for offshore wind farms while minimising ecological risks to seabird populations.

14.10.25

BTO Research Reports

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