Climate change poses a major threat to biodiversity, not only because of increasing temperatures, but also because of more frequent and more severe extreme weather, so we need to understand how species may be affected by this. The study looks at the effects of climate extremes on British bird populations and contributes to understanding how the impacts of climate change on biodiversity can be mitigated. Climate change is one of the major threats to species conservation. Biological responses to climate change include shifts in species distribution, behavioural and physiological changes. However, many species will not be able to adapt and therefore their populations will decline and some may even become locally or globally extinct. Climate change is not just a smooth increase in temperature but it has many severe and diverse impacts on weather patterns. In particular, extreme weather conditions, such as heat waves, droughts, and storms, are becoming more severe and more common. This collaborative study led by the University of Milano-Bicocca has looked at how British birds have responded to climate extremes so far, to understand the consequences for birds of more extreme weather in the future. The BTO/JNCC/RSPB Breeding Bird Survey (BBS) played a key role in this work, because the bird counts collected by BBS surveyors are incredibly useful in understanding how population change over time. The researchers looked at how the population of 100 resident species changed as a consequence of five indices of extreme climate: number of frost days, number of days with temperature higher than 25 °C, daily temperature range, amount of precipitation per day in wet days, and number of dry days. Results show that all 100 species were sensitive to at least one of the five indices of climate extreme. In particular, most species were negatively affected by winter frost days, summer days, and amount of precipitation per day in wet days. The response to the other two indices (number of dry days and daily temperature range) was more diversified, with both positive and negative effects depending on the species.

GPS tracking sheds light on the ‘barrier effects’ of offshore wind farms, where renewable energy developments may act as obstacles that impede the movements of seabirds to and from their colonies during the breeding season, or on migration. Between 2016 and 2019, BTO scientists fitted Sandwich Terns breeding at Scolt Head Island in Norfolk with long-life GPS tags which tracked the birds’ movements over multiple years. When the research began, there were five operational offshore wind farms within the distance that Sandwich Terns are known to fly on foraging trips. Two more offshore wind farms were under construction, and became operational during the course of the study. The results revealed that Sandwich Terns entered offshore wind farms, but the extent to which they used these areas varied over time and between sites. For the two wind farms that were completed during the study, there was a marked reduction in the amount of time birds spent at these sites between the first and second year of operation. Although birds sometimes entered offshore wind farms while foraging, they appeared to avoid them when commuting between foraging areas and their colony. This created an apparent ‘funnelling’ effect between important feeding locations. The changes found could be driven by changes to the birds’ sandeel prey distribution, avoidance of wind farms, or changes in airflow patterns following wind farm construction. The study shows that the responses of seabirds to offshore wind farms are many and complex. Further research is needed to fully understand the nature of these interactions, at a time when ever more wind farms are being constructed to mitigate the impacts of climate change.

Determining flight heights for seabirds is a crucial prerequisite for understanding collision risks associated with offshore wind farms, but obtaining these can be challenging. This comment addresses concerns over the workflow proposed by Humphries et al. (2023).

Moult is an essential but understudied life-history event in birds, and one that is difficult to study with current statistical approaches. This paper presents an extended modelling framework that should remove barriers to modelling the phenology of moult.

Birds may exhibit a range of different movement patterns, from the dispersal that takes them away from the nest in which they were raised, through to annual migrations between breeding and wintering areas located thousands of miles apart. Some of these movements are more difficult to study than others, and this is particularly true for those species that are nomadic in their behaviour. International research led by BTO has revealed that Short-eared Owls make astonishing nomadic migrations between nest sites as far apart as Scotland and Arctic Russia.