Action to reduce anthropogenic impact on the environment and species within it will be most effective when targeted towards activities that have the greatest impact on biodiversity. To do this ...effectively we need to better understand the relative importance of different activities and how they drive changes in species' populations. Here, we present a novel, flexible framework that reviews evidence for the relative importance of these drivers of change and uses it to explain recent alterations in species' populations. We review drivers of change across four hundred species sampled from a broad range of taxonomic groups in the UK. We found that species' population change (~1970-2012) has been most strongly impacted by intensive management of agricultural land and by climatic change. The impact of the former was primarily deleterious, whereas the impact of climatic change to date has been more mixed. Findings were similar across the three major taxonomic groups assessed (insects, vascular plants and vertebrates). In general, the way a habitat was managed had a greater impact than changes in its extent, which accords with the relatively small changes in the areas occupied by different habitats during our study period, compared to substantial changes in habitat management. Of the drivers classified as conservation measures, low-intensity management of agricultural land and habitat creation had the greatest impact. Our framework could be used to assess the relative importance of drivers at a range of scales to better inform our policy and management decisions. Furthermore, by scoring the quality of evidence, this framework helps us identify research gaps and needs.
The estimated number of Western Capercaillies Tetrao urogallus in Scotland in winter 2021-2022 was 532 with a 95% confidence interval (CI) of 227-810.
To produce an updated estimate of the number of ...Western Capercaillies in Scotland.
Line transects were surveyed across the current distribution, sampling in two separate strata: a primary stratum in the core range and a secondary stratum in peripheral areas. Multi-covariate distance sampling was used to fit alternative detection functions to the sighting data, deriving national, regional and sex-specific estimates of abundance.
The survey recorded 115 Western Capercaillies in 104 separate encounters across 635 transects, yielding a population estimate of 532 individuals (95% CI: 227-810). This estimate was 52% lower than from the population survey in 2015-2016 (1114 individuals, 95% CI: 805-1505). Declines were greater for females than for males, leading to an adult sex ratio in favour of males. Most of the population (80%) continues to be concentrated in the region of Badenoch and Strathspey.
With the population at its lowest level since the start of national monitoring in 1992-1994, the likelihood of extinction in Scotland for a second time seems inevitable without a step-change in conservation action. Measures to improve breeding success and survival are needed and should be targeted in the core of the range to maximize impact on the population.
CapsuleThe first UK European Turtle Dove Streptopelia turtur survey, in 2021, estimated the breeding population at 2092 territories.AimsChanges in European Turtle Dove abundance in the UK have been ...monitored through schemes like the BTO/JNCC/RSPB Breeding Bird Survey, however, sample size is now too low to calculate robust trends going forward. The aims of this volunteer-based survey were to provide a new UK population estimate and create a baseline to monitor future population trends.MethodsA stratified random sample of one-kilometre squares were surveyed within the core counties for the species. Elsewhere, one-kilometre squares containing recent European Turtle Dove records were targeted. The survey used a two-visit territory mapping approach, with observers asked to get within 200 metres of potentially suitable nesting or foraging habitat. Visits were undertaken in the early morning, to coincide with peak vocal activity, from 11 May to 31 July.ResultsThe UK population estimate in 2021 was 2092 territories (95% confidence limits, 1559–2782). The species has become increasingly restricted to eastern and southeastern England, with 62.5% of the population estimated to occur in three counties: Kent (682 territories; 32.6%), Suffolk (326; 15.6%) and Essex (300; 14.3%). Additional hotspots occurred in other counties in eastern England, up to North Yorkshire.ConclusionThis result suggests a 98% decline in abundance since the 1968–1972 breeding atlas, similar to trends identified from UK bird monitoring schemes, and a substantial contraction in range since the 2007–2011 bird atlas. The temporary cessation of hunting along their European western flyway provides a vital window of opportunity to scale up the delivery of high-quality breeding habitat and increase food availability in the UK. The survey should be repeated in 2026, and regularly thereafter, to help monitor the effectiveness of conservation interventions.
Enhancement of farmland biodiversity is a key objective of agri-environment schemes in Europe, and conservation of the rare and threatened cirl bunting (
Emberiza cirlus) has been a key objective for ...the Countryside Stewardship Scheme (CSS) in south Devon, UK. Cirl bunting numbers increased by 83% on land entering CSS management agreements between 1992 and 1998, compared with an increase of just 2% on adjacent countryside not managed under CSS. The increase in cirl buntings on stewardship land was part of a wider regional increase in abundance rather than a redistribution of birds away from land not under stewardship. In 1998, 22% of all UK cirl buntings were breeding on land under CSS agreements and a further 16% of birds were within 0.5 km of land under stewardship. All but one of the 27 agreements that gained cirl buntings were within 2 km of cirl bunting breeding sites in 1992, with more distant agreements failing to be colonised even if they offered a range of potentially beneficial prescriptions. Agreements providing grass margins around arable fields, weedy winter stubbles and open patches of grassland next to scrub tended to gain additional cirl buntings. Grass margins and weedy winter stubbles constitute important food-rich habitats for cirl buntings and other farmland birds, and should be encouraged in future agri-environment agreements and schemes.
Capsule: The fifth UK and the Isle of Man survey of Hen Harrier in 2016 showed varying trends by country and region.
Aim: To estimate the size of the breeding Hen Harrier population (with associated ...95% confidence intervals) in the UK and Isle of Man, constituent countries and Scottish regions, in 2016 and calculate population change over the five surveys to date.
Methods: Complete surveys were made of all 10-km squares likely to be occupied by breeding Hen Harriers in England, Wales, Northern Ireland and the Isle of Man, using standard methods developed for previous national surveys. In Scotland, self-selected 10-km squares were surveyed by volunteers and a stratified random selection of the remaining 10-km squares within the known breeding range was surveyed.
Results: The UK and Isle of Man Hen Harrier population was estimated at 575 territorial pairs (95% confidence limits, 477-694), a non-significant decline of 13% since 2010 but a significant decline of 24% since 2004. Scotland held the majority (80%) of the population with 460 (359-573) territorial pairs. Elsewhere, 46 territorial pairs were recorded in Northern Ireland, 35 in Wales, 30 in the Isle of Man and four in England. Significant decreases were recorded in the number of pairs in Scotland using grouse moor (−57%) and young forest (−54%).
Conclusion: The combined breeding population of Hen Harriers in the UK and Isle of Man has shown a non-significant decline between 2010 and 2016. There were notable decreases in England, Northern Ireland and Wales since 2010.
Capsule The UK Corncrake population increase has slowed, but has rapidly recovered from a large decline in 2013. Aims To provide an update on the population size and distribution of breeding ...Corncrakes in the UK, including the results of the most recent full national survey and annual monitoring of the core population. Methods A full survey of singing Corncrakes was undertaken in the UK and the Isle of Man in 2009, following the last full censuses in 1978/79, 1988, 1993, 1998 and 2003. Monitoring of singing male Corncrakes within the core range in northern and western Scotland has been undertaken annually since 1993. Results The 2009 results show that numbers increased substantially since 2003, from 829 to 1166 singing males. Corncrake numbers in the core range have increased in 17 of the 21 years between 1993 and 2014, and peaked at 1274 singing males, in 2014. Numbers of singing males dropped by 24% between 2012 and 2013, probably due to a particularly cold spring in 2013 that inhibited growth of vegetation cover, but numbers recovered markedly in 2014. Conclusion The recovery of the UK Corncrake population has continued since a low point in 1993. However there are no signs of range expansion into mainland UK, away from the core breeding areas in Scotland. The large decline in the core population between 2012 and 2013 highlights the sensitivity of the population to external factors, although the subsequent increase in 2014 shows a capacity for rapid recovery.
Capsule: There were up to 6348 Ring Ouzel territories in the UK in 2012.
Aims: To produce estimates of the size of the Ring Ouzel breeding population in the UK and its constituent countries.
Methods: ...A stratified random selection of tetrads was surveyed within the known breeding range, except for the remaining breeding areas on Dartmoor and historical sites elsewhere, which were surveyed in their entirety. The methods followed those devised for the first UK-wide survey in 1999, using playback of song at specific points along tetrad transect lines.
Results: The UK population estimate in 2012 was 5332 (95% confidence limits (CL), 4096-6875) territories, a non-significant decline of 29% since 1999. There were no significant differences in the population changes in England, Scotland and Wales between the two surveys. An estimation of survey efficiency found that 84% of territories were located by the national survey methods, suggesting that the UK population in 2012 could have been as many as 6348 (95% CL, 4825-8198) territories.
Conclusion: The results suggest that the UK Ring Ouzel population has continued to decline since 1999. Ongoing and future research should determine where the main threats to the population are: on the breeding or wintering grounds, or during migration.
Two conservation strategies have been put in place in Europe to address precipitous population declines of wading birds that breed on lowland wet grasslands. These are site protection and ...agri‐environment schemes (AESs) and the two are rarely compared, or their synergy assessed. Increasingly, efforts to recover populations of previously widespread species follow a landscape‐scale approach whereby habitat improvement takes place at key sites through partially overlapping protected area management and AESs. To investigate whether site protection and AESs improve the conservation status of breeding waders and how these interact, we partially repeated a 2002 survey of breeding waders on protected areas (nature reserves and Sites of Special Scientific Interest) and sites with wader‐specific AES options in England in 2009 and 2010. We then assessed the individual and combined effects of these delivery mechanisms on field occupancy, breeding density and population change of four species of declining wader (Northern Lapwing Vanellus vanellus, Common Snipe Gallinago gallinago, Eurasian Curlew Arquata numenius and Common Redshank Tringa totanus). Although results for Curlew differed from the other species, in general field occupancy was positively influenced by conservation delivery mechanisms, with the highest occupancy and breeding densities on land where site protection was combined with wader‐specific AES options. Field occupancy varied between different types of AES, with higher occupancy associated with higher‐level options in fields, particularly those on nature reserves. Outside nature reserves, the history of AES management did not influence wader populations, but within nature reserves and on fields that gained AES management between 2002 and 2009–2010, populations of Curlew and Snipe were more likely to have persisted and population change in Snipe and Lapwing was more positive. We conclude that the conservation of breeding waders will be most effective when site protection and AES management are combined on the same land. Using limited AES money to support management for breeding waders on, around and between the existing network of protected sites will protect remaining populations while presenting opportunities for population expansion in future.
The decline of the Bittern Botaurus stellaris has long been symbolic of wetland habitat loss and fragmentation across western Europe. Wetland restoration and creation activity, targeted at Bittern, ...has been ongoing in the UK for more than 10 years and the overall numbers of occupied sites has increased five‐fold in that time. The strong recovery, whilst cause for celebration, disguises the continued precariousness of the population. This recovery has predominantly been fuelled by chick productivity from three sites in coastal Suffolk and there is increasing awareness that these sites are in immediate danger from rising sea levels. A key question is whether any loss of these key sites to coastal flooding matters to the UK Bittern population. A cautious approach to mathematical modelling of the sensitivity of the UK Bittern population to sea‐level rise events suggests that we should be concerned about the long‐term future. Our models demonstrate the sensitivity of the UK population to changes in chick survival and suggest that the growth of the UK Bittern population would be negatively affected by the loss of even a proportion of nests from these three key sites. These findings prompt the need for a multi‐layered conservation strategy to meet this dynamic challenge. A potential way forward is discussed.
The Dartford Warbler Sylvia undata has recently expanded its range northwards and upwards in the UK, consistent with the hypothesis that this cold-sensitive species has responded to a warming ...climate. We interrogated distribution data, collected during four national surveys of this species between 1974 and 2006, to assess whether this large-scale range expansion has been accompanied by finer-scale changes in topographic characteristics of breeding locations. Within sites occupied in successive surveys, there was some evidence of limited altitudinal expansion between surveys. Within wider landscapes occupied in successive surveys, the preceding winter climate tended to be harsher at newly colonized sites than at sites that had already been occupied in the previous survey, while territories in newly colonized sites also tended to be on steeper slopes, especially if at higher altitude, and (in 1994 only) to be more south-facing. Territories in sites that had already been occupied in the previous survey tended to be lower altitude, less steep and more north-facing than territories in newly colonized landscapes. In 2006 only, the winter climate was significantly milder in newly colonized landscapes than in already occupied sites. The combined effects of a changing climate and topography may have influenced the pattern of in-filling in the existing range, while colonization of distant areas, especially more latterly, may have been facilitated by a combination of increased dispersal pressure from the existing range and warming of climate which made higher altitude habitat in the new areas more suitable for occupancy. Careful consideration needs to be given to the importance of fine-scale topographical variation in determining species' responses to climate change in order to underpin robust adaptation strategies.
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