New BTO research shows that Lesser Black-backed Gulls are vulnerable to collisions with wind turbines whilst on migration and during the winter months, as well as during the breeding season. Wind turbines both on and offshore are becoming ever more prevalent as governments worldwide seek to tackle carbon emissions. It is important to understand how these structures might affect wildlife. In this study, BTO researchers fitted state-of-the art GPS tags to Lesser Black-backed Gulls breeding at three major UK colonies in order to track their movements throughout the year. By combining the data from the tags with information on wind turbine locations they were able to establish how vulnerable this species might be to collisions. The GPS devices recorded how fast and how high birds fly, as well as the time birds spent in particular areas. This information was used to estimate the risk of birds colliding with wind turbines when flying at altitudes swept by the turbines’ blades. The results showed that Lesser Black-backed Gulls are vulnerable during the breeding season, when birds are tied to feeding areas close to their colonies, many of which are also in the vicinity of wind farms. Furthermore, birds were also found to be at risk once the breeding season is over and they disperse south to Spain, Portugal and north Africa, where they overwinter. Galicia in northern Spain stood out as a place in which birds were vulnerable on migration, as this region contains a high density of wind turbines, and is a major stopping over destination for the Lesser Black-backed Gull and many other migratory species. Further south, Lisbon and Malaga, where many Lesser Black-backed Gulls spend the winter, were also sites in which birds were vulnerable to collisions. The results are the first to show where and when birds from specific breeding colonies may be most vulnerable across their annual life cycle, and could be useful in helping to identify where best to site new wind farms to minimise potential harm to wildlife.

Research by BTO and Natural England, modelling the impact of a suite of climatic variables on the abundance of breeding bird species in England, suggests that climate change has had a detectable impact on a sizeable proportion of England’s avifauna over the last 50 years. The results of the study provide evidence that can inform future assessments of species’ vulnerability. Climate change is widely regarded as a major threat to the functioning of natural systems and to the maintenance of species’ populations. Birds are one of the taxa where climate change impacts have been most studied, the research demonstrating a range of documented responses, including advancement in the timing of migration and breeding, poleward shifts in distribution, and changes in community structure. While such work highlights some of the effects of climate change, the attribution of specific changes in species’ populations to a changing climate remains challenging. The research reported in this paper examines the potential impacts of climate change on individual species for as wide a component of England’s breeding avifauna as is currently possible. The study used data from the BTO’s Common Bird Census and the BTO/JNCC/RSPB Breeding/Bird Survey to generate annual indices of population change for 68 species, from 1966 to 2015. These data were then examined in relation to changes over time – and differences between regions – in a series of climatic variables derived from the National Oceanic and Atmospheric Administration / Earth System Research Laboratory, Physical Sciences Division series. This enabled Pearce-Higgins and Crick to consider climatic variables across the different geographical regions of relevance to individual species. For example, climatic conditions in England, Iberia and the Sahel region of Africa needed to be considered when examining population changes in those migrant species breeding in England but wintering in Africa’s arid-zone and migrating via Spain and Portugal. The results of the statistical analyses suggest that climate change has had a measurable effect on the population fluctuations of about a third of the breeding species considered, resulting in notable positive impacts on the abundance of 13 species and notable negative impacts on three species. The majority of the effects found related to climatic conditions within England, which were particularly apparent for resident species during summer and winter. These findings support previous BTO work, highlighting the role of winter temperature as a key driver of resident bird populations, including Goldcrest, Long-tailed Tit and Dunnock. With the exception of Common Whitethroat, Reed Warbler and Spotted Flycatcher, the study failed to find strong evidence for significant effects of climatic conditions away from the UK impacting on migratory species, something that may reflect the difficulty of assessing climate changes impacts on migratory birds, brought about in part by our incomplete knowledge of the migration routes and wintering areas for many of these species. This emphasizes that research seeking evidence for climatic impacts on species must also include a mechanistic understanding of the potential links between climatic variables and the population of interest. Gaining such understanding is an important component of current BTO work on migrant bird populations, with the knowledge gained on migration routes, wintering areas and differences between regional breeding populations key to future work.

New BTO research has used citizen science data to assess the effects of housing developments on Britain’s bird populations, predicting that almost half of the bird species currently found on sites earmarked to become the government’s flapship ‘garden villages’ could decline once development starts. Like in many countries, Britain faces the challenge of housing a growing population, but urban expansion to address this can lead to locally high rates of biodiversity loss, along with fragmentation of natural and semi-natural habitats. In Britain, most new housing is built on farmland or previously developed land, not on pristine natural habitat, meaning lessons from elsewhere may not be useful when assessing the effect of housing developments on wildlife. The BTO study used data collected by volunteers during the Bird Atlas 2007–11 project to assess how bird populations vary along a gradient from farmland to city centre. For 146 breeding and wintering bird species in England and Wales, bird abundance was related to the number of people living in each area surveyed. As expected, species such as Skylark were completely intolerant of any form of development, while others such as Feral Pigeon thrived in heavily developed landscapes. Species like Song Thrush were intermediate, becoming more common in the suburbs and other places with moderate human populations than in either open countryside or urban centres. Although these relationships may seem obvious, knowing at precisely what levels of development each species' abundance changes is crucial for estimating how birds will be affected in future. For example, the study examined the possible effects of the UK government’s 14 proposed garden villages on local bird populations. The results suggested that under current plans, the abundance of approximately 47% of species breeding at the garden village sites is likely to reduce in response to the proposed development, with 18% expected to undergo no statistically significant abundance change and 35% expected to increase. However, various measures were found to improve the situation for birds, such as including patches of trees and wetland areas in the garden village designs. Previous work involving the BTO has demonstrated that contact with birds improves people’s well-being, so understanding the effect of housing development on bird numbers has important implications for the future human residents of these villages as well as for the birds themselves. The results of this research can now be used to develop tools to help developers and planners optimise the design of new developments, both to benefit wildlife and the people that live there.