Understanding how human activities drive biodiversity change at different spatial scales is a key question for conservation practitioners and decision-makers. While we have a good understanding of the primary causes of observed biodiversity declines – which include land-use change, climate change, pollution, and the over-exploitation of species – we still struggle to measure and detect biodiversity change in robust and meaningful ways.

Human activities modify the availability of natural resources for other species, including birds, and may alter the relationships between them. The provision of supplementary food at garden feeding stations, for example, might favour some species over others and change the competitive balance between them. This paper investigates the behavioural responses to competition of the Marsh Tit, a species that is subordinate to both the Blue Tit and the Great Tit.

Butterflies are among the most visible garden invertebrates, and the garden habitat has been recognised as a potential refuge for these charismatic species. However, we know very little about the changing fortunes of garden butterfly populations because gardens are not well-represented in traditional monitoring schemes. This study highlights the role that BTO Garden BirdWatch could play in identifying and reporting on annual trends in butterfly populations. BTO Garden BirdWatch (GBW) is the UK’s largest structured bird survey, delivering over 25 years of weekly bird counts from more than 14,000 gardens, predominantly occupying suburban and rural locations. Since 2007, a subset of GBW participants has additionally recorded the weekly abundances of butterflies, and it is these data – drawn from 7,971 gardens over the period 2007 to 2020 – that have been used to produce garden-specific abundance trends for 22 widespread butterfly species. The team of researchers, bringing together staff from BTO and Butterfly Conservation, used a statistical approach developed for butterfly data, first estimating seasonal flight curves – the pattern of abundance throughout the flight period – for each species and calculating the mean relative abundance across sites for each year, before then modelling the long-term trend for the species concerned. The results showed that half of the species investigated had increased significantly in abundance in gardens between 2007 and 2020. Conversely, only one species – Wall – showed a marginal reduction, though this change was not statistically significant. Importantly, a strong, positive association between these new, habitat-focused trends and those for UK butterflies more broadly, previously reported by the UK Butterfly Monitoring Scheme (UKBMS), indicates that patterns of abundance in gardens are largely a reflection of the changes that are occurring nationally. However, the results indicate that butterflies appear to be faring better in gardens compared to the wider landscape, with GBW recording significantly greater increases over time than UKBMS. The study demonstrates that GBW butterfly recording can produce reliable and informative population trends, and it also provides important evidence of the significant role gardens play in sustaining butterfly populations across a wider area.

A large tracking dataset was used to assess the behavioural responses of migrating Curlew to offshore windfarms, of which there are many in the North Sea and Baltic Sea. Most individuals showed medium-scale avoidance responses in the horizontal and vertical planes. Up to 15.8% of the individuals migrated at elevated risk without showing avoidance reactions. Collision risk and energetic constraints by circumventing the turbines are discussed.

A review paper by BTO considers 203 studies of the effects of air pollution on 231 bird species. Of these studies, 82% document at least one negative effect associated with increasing levels of pollution. The review also highlights biases towards particular study species, especially Great Tit and Pied Flycatcher, and also towards particular geographical regions (Western Europe) and pollutants (heavy metals). The paper proposes research approaches that could help to provide a fuller understanding of how birds are impacted by air pollution.

Understanding how human activities influence biodiversity change at different spatial scales is one of the key questions in our attempts to tackle biodiversity loss. This study, using the most comprehensive dataset of its kind, sought to understand the drivers of population change in European birds.

In this study, BTO scientists mapped large fires that occurred over a 19-year period in Polesia, a region containing some of Europe’s last pristine peatlands and lowland forests in Eastern Europe. Fires are of great concern to policymakers in the region due to the economic and health costs, and a lot of resources are used to suppress fires during hot and dry years. There are potentially natural solutions to fires, however, that could also benefit birds, biodiversity and climate issues. These ‘nature-based’ solutions include restoring drained wetlands. In this study, freely-available satellite data were used to explore the prevalence of large fires and the factors causing them. This allowed researchers to explore whether restoring the landscape’s wetlands could reduce the increasing risk of large, damaging fires as the climate changes.