In a changing world, the development of green energy is more important than ever. One of the most well-developed and cheaply available options is wind power, but there is evidence that wind farms can also have a negative impact on biodiversity. This 2017 study, funded by the Cambridge Conservation Initiative and led by BTO, is the first to look at the global impact of wind farms on bird and bat populations. Although the most obvious threat from wind turbines is that of collisions, as birds fly into the turbine, the threats from wind farms are not solely collision-based. They also have the potential to displace species from their nesting or feeding areas, restrict movements, or destroy key habitats used by different species. The study reviewed 234 papers which look at both bat and bird collision rates with wind farms. These were then examined in relation to several of the factors that may play a role in collisions, including the physiological and behavioural traits of individual species, and the height and energy output of turbines. The results show that birds using ‘artificial habitats’ (e.g. farmland or urban areas) run a higher risk of colliding with wind turbines than birds living elsewhere, although this could be due to the fact that many wind farms are located within such habitats. Perhaps unsurprisingly, migratory birds faced a greater risk than sedentary ones; similarly, species of bat which dispersed further, on average, had a higher risk of collision than those that didn’t. Out of the 362 bird species examined, 55 were considered as being ‘threatened’ by wind farms. Thirty-one of these were birds of prey, species that are generally slow to reproduce and which are more sensitive to the impact of losing breeding adults to wind turbines. Collision rates in general were predicted to be higher for bats than for birds, emphasising their vulnerability to wind farms. Individually, larger turbines were associated with a higher collision rate than small turbines, but wind farms comprising a large number of smaller turbines resulted in the highest rates of collision. In practical terms this suggests that using a few large turbines may lower collision rates for birds, although it is worth noting that turbines with a capacity of more than 1.25 MW were linked to high collision rates for bats. Given the growing demands for green energy, it is essential that we consider the impacts of wind farms on populations of both bats and birds, especially migrants and wide-ranging species. Taking into account knowledge of the birds and bats using an area when considering the placement of wind farms and individual turbines (e.g. by avoiding migratory flyways) could greatly reduce the risk of collisions. The work also underlines a need for more research to be carried out in emerging economies and in relation to offshore wind farms, both of which are areas where valuable information is currently lacking. This will surely help to find the delicate balance between a greener future and healthy biodiversity.

Wader populations are declining worldwide, with causes often being linked to the loss and degradation of habitats, increased predation, and a changing climate. Here in the UK, we have seen dramatic declines in Curlew populations over recent decades, resulting in the species being proposed as the UK’s most important bird conservation priority. If we are to halt and reverse these declines then we first need to understand which threats this iconic species is facing.

The UK has lost seven species of breeding birds in the last 200 years. Conservation efforts to prevent this from happening to other species, both in the UK and around the world, are guided by species’ priorities lists, which are often informed by data on range, population size and the degree of decline or increase in numbers. These are the sorts of data that BTO collects through its core surveys. For most taxonomic groups the priority list is provided by the International Union for Conservation of Nature (IUCN) – the IUCN Red List comprises roughly 12,000 species worldwide and their conservation status. However, for birds in the UK, most policy makers refer to the Birds of Conservation Concern (BoCC) list, updated every six years (most recently in 2015). A new study funded by the RSPB and Natural England in cooperation with BTO, WWT, JNCC, and Game & Wildlife Trust has carried out the first IUCN assessment for birds in Great Britain. The study applied the IUCN criteria to existing bird population data obtained from datasets like the BTO/JNCC/RSPB Breeding Bird Survey (BBS). The criteria take into account various factors, most notably any reduction in the size (both in abundance and range) of populations, loss of habitats key to the species, small or vulnerable population sizes, and extinction risk. Alongside this, the criteria look to see if there is a “rescue” effect – such as immigration from neighbouring populations that might boost the population’s numbers, reducing the risk of extinction. The species are then categorised into one of the threat levels below. The results of the new study show that a concerning 43% of regularly occurring species in Great Britain are classed as Threatened, with another 10% classified as Near Threatened. Twenty-three breeding or non-breeding populations of birds were classed as Critically Endangered, including Fieldfare and Golden Oriole (both possibly extinct as breeders), Whimbrel, Turtle Dove, Arctic Skua and Kittiwake, as well as non-breeding populations of Bewick’s Swan, White-fronted Goose and Smew., Over the past 200 years, seven species have gone extinct as breeders in Britain, including Serin, Temminck’s Stint and Wryneck in the past 25 years. The total percentage of threatened birds in Great Britain (43%) is high compared to that seen elsewhere in Europe (13%). Reasons for this are not entirely clear, although it may be that Britain’s island status has something to do with this, as there are fewer neighbouring “rescue” populations. Although the results from the IUCN assessment and BoCC assessment largely overlap, the IUCN assessment raises the level of concern for species such as Red-Breasted Merganser, Great Crested Grebe, Moorhen, Red-Billed Chough (all classed as Vulnerable), and Greenfinch (Endangered). These species might thus warrant closer monitoring in the near future. In contrast, the BoCC assessment identifies a number of species of concern whose declines have been more gradual but over long time periods (e.g. Skylark and House Sparrow). The authors emphasise that this assessment is not a replacement of the BoCC report, but rather that the two reports complement each other. With this new wealth of knowledge, there will hopefully be even more support for those species that need it most.

1. Individual-based models (IBMs) are a powerful tool in predicting the consequences of environmental change on animal populations and supporting evidence-based decision making for conservation planning. 2. There are increasing proposals for wind farms in UK waters and seabirds are a vulnerable group, which may be at risk from these developments. 3. We developed a spatially explicit IBM to investigate the potential impacts of the installation of wind farms in the English Channel and North Sea on body mass, productivity and mortality of a breeding population of Northern gannets for which we have tracking data. 4. A baseline model with no wind farms accurately represented the status of a sample of tracked gannets at the end of the 90-day chick-rearing period, and the behaviourtime budget was similar to that of tracked gannets. 5. Model simulations in the presence of wind farms indicated that installations should have little impact on the gannet population, when either avoidance behaviour or collision risk scenarios were simulated. Furthermore, wind farms would need to be ten times larger or in more highly used areas in order to have population-level impacts on Alderney’s gannets. 6. Synthesis and applications. Our spatially explicit individual-based models (IBM) highlight that it is vital to know the colony-specific foraging grounds of seabirds that may be impacted, when identifying potential wind farm sites, in order to account for cumulative impacts from multiple sites. Avoiding areas highly used for foraging and commuting, and avoiding large-scale developments should be effective in limiting gannet mortality as a result of collision, competition and energy expenditure. Our IBM provides a robust approach which can be adapted for other seabird populations or to predict the impacts from other types of spatial change in the marine environment. 1. Individual-based models (IBMs) are a powerful tool in predicting the consequences of environmental change on animal populations and supporting evidence-based decision making for conservation planning. 2. There are increasing proposals for wind farms in UK waters and seabirds are a vulnerable group, which may be at risk from these developments. 3. We developed a spatially explicit IBM to investigate the potential impacts of the installation of wind farms in the English Channel and North Sea on body mass, productivity and mortality of a breeding population of Northern gannets for which we have tracking data. 4. A baseline model with no wind farms accurately represented the status of a sample of tracked gannets at the end of the 90-day chick-rearing period, and the behaviourtime budget was similar to that of tracked gannets. 5. Model simulations in the presence of wind farms indicated that installations should have little impact on the gannet population, when either avoidance behaviour or collision risk scenarios were simulated. Furthermore, wind farms would need to be ten times larger or in more highly used areas in order to have population-level impacts on Alderney’s gannets. 6. Synthesis and applications. Our spatially explicit individual-based models (IBM) highlight that it is vital to know the colony-specific foraging grounds of seabirds that may be impacted, when identifying potential wind farm sites, in order to account for cumulative impacts from multiple sites. Avoiding areas highly used for foraging and commuting, and avoiding large-scale developments should be effective in limiting gannet mortality as a result of collision, competition and energy expenditure. Our IBM provides a robust approach which can be adapted for other seabird populations or to predict the impacts from other types of spatial change in the marine environment.

Populations of Afro-Palearctic migrant birds, which breed in Europe but winter in Africa, have shown severe declines in recent decades. To identify the causes of these declines, accurate measures of demographic rates (e.g. the number of fledglings per season, estimated survival from year to year, and immigration from other populations) are needed to allow effected targeting of conservation and research activities. A new study by the BTO and the University of Lancaster focused on the Whinchat population of Salisbury Plain (Wiltshire), which has remained relatively stable against the declining European trend. From 2010 to 2014 Whinchats were studied in detail to measure demographic rates. Adults and nestlings were colour-ringed to calculate survival rates for adult and first year birds, while nests were found and monitored to measure breeding success. Intensive surveys to census Whinchats and re-sight colour-ringed birds were also carried out each year, which allowed natal and breeding dispersal to be calculated, i.e. how close to their previous year’s hatching site or nest site, respectively, Whinchats return. These demographic rates were then used to build a population model to show how both on-site and external factors contribute to population change. Surprisingly, considering the relative stability of the population, the study identified low seasonal breeding success due to nocturnal predation and low apparent first year survival. This indicated a declining population trend. However, this trend was not reflected in the observed census counts, suggesting that high immigration from other UK breeding populations was probably balancing this decline. The study demonstrates the potential of high quality breeding habitat, such as that on Salisbury Plain, to lower the rate of population decline. However, due to this population’s reliance on immigration, it will remain vulnerable in the future if the decrease in the wider UK population continues to reduce the pool of potential newcomers. The results suggest that focusing conservation action on improving breeding success is likely to be an important immediate conservation strategy for Whinchats in Europe. In the long term, greater research emphasis is needed on migrant birds generally, as well as the factors that influence their immigration. It should also concentrate on separating first year fledglings’ dispersal and survival rates. Lastly, and importantly, it should focus on understanding the relationship between changes in demographic rates and the population trend in Whinchats, which could have implications for the conservation of wider Afro-Palearctic migrants as a whole.