Data from bird ringing show changes in the timing of birds feeding up before their autumn migration across Europe over the past 40 years, and a decrease in the extent of fattening recorded. This decline was strongest in southern Europe and was linked to rising temperatures associated with climate change.

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.

BTO has a long history of supporting long-running national monitoring schemes such as the Breeding Bird Survey, Wetland Bird Survey, Seabird Monitoring Programme and Nest Record Scheme. As well as national scale information on birds that these surveys provide, there is also a growing demand for monitoring at smaller spatial scales, from National Parks and estates to smaller local wildlife sites. Often, the best evidence of the efficacy of particular interventions comes from smaller scale monitoring. However, the design and set up of a monitoring programme can be challenging. This guide is aimed at the organisers of – and participants in – local scale monitoring projects. It deals with the fundamental questions of what you might want to measure and why; how to choose between established methods for sampling and counting; and how to manage your volunteers and the data they collect. Readers are encouraged to use methods that closely align with those used in national schemes. By collecting data in a particular way, comparisons between local- and national-level data become possible, so giving added value to the data collected. As well as this guide on how to collect data, we now also publish the data and analysed outputs from smaller spatial scales, derived from the wide range of our national volunteer monitoring schemes. For information on how birds have changed in your county, Local Nature Recovery Strategy area or bird recording area, please visit out BirdFacts Places site. You might find that the information you need is already available. This guide is also available from Zenodo and carries a DOI: doi.org/10.5281/zenodo.15657012

Research involving BTO shows bird species moving toward colder areas in the mountains of Europe as the climate has warmed over the past two decades.

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.

Cuckoos are brood parasites, meaning they lay their eggs in other species' nests, and the resulting chicks are raised by the host species. Cuckoos therefore face strong evolutionary pressure for their eggs and offspring to match those of their hosts, yet each Cuckoo species parasitises multiple hosts. This study examines the genetic basis of egg coloration in the Common Cuckoo and the Oriental Cuckoo.