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.

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.

This report, which is an addendum to BTO Research Report 766, examines the potential impacts of current and proposed wind farm developments on the Red Kite population in Wales

This BTO Research Report explores the ability of data collected through the Bailiwick Bat Survey to produce robust long-term monitoring trends for a suite of species.

Thanks to our members, funders and supporters, £7.3 million was spent during the year carrying out, supporting and communicating our ornithological research and delivering engagement. Through our Bird Study journal, we brought together 22 important scientific papers that shed new light on the avian influenza outbreak and help direct our response to this devastating disease. Our Together Through Nature (Thetford) project has given us the foundations needed for a successful community project, working with people who don’t usually have the opportunity to engage with nature and BTO. Some 43,679 BTO volunteers have contributed to Garden BirdWatch, which has celebrated 30 years of recording this year, generating 10.6 million weekly observations. Volunteers contributed 2,643,682 hours to BTO work during the year, mainly through our bird surveys and monitoring schemes. This incredible effort has an estimated financial value of more than £54 million. During 2024/25, we received just under £800,000 through gifts in Wills, something for which we are phenomenally grateful.

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.

Sporting and leisure activities are common at the Northern Irish sea loughs. Human-related disturbances to foraging or resting waterbirds can come from a range of sources, from people on foot or using machines or vehicles, and from industrial or recreational activities. Such disturbances may cause birds to fly away to alternate areas or cause non-fleeing responses like increased vigilance. This pilot project builds on the findings of an analysis of within-site wintering waterbird trends, and provides a more targeted field-based study that directly assesses the potential responses of waterbirds to disturbance. A particular focus of the work is disturbance associated with intertidal aquaculture activities at sites across Northern Ireland, and the report seeks to set these in the context of disturbance events caused by other activities.