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Background Identifying blood-based signatures of brain health and preclinical pathology may offer insights into early disease mechanisms and highlight avenues for intervention. Here, we systematically profiled associations between blood metabolites and whole-brain volume, hippocampal volume, and amyloid-β status among participants of Insight 46—the neuroscience sub-study of the National Survey of Health and Development (NSHD). We additionally explored whether key metabolites were associated with polygenic risk for Alzheimer’s disease (AD). Methods Following quality control, levels of 1019 metabolites—detected with liquid chromatography-mass spectrometry—were available for 1740 participants at age 60–64. Metabolite data were subsequently clustered into modules of co-expressed metabolites using weighted coexpression network analysis. Accompanying MRI and amyloid-PET imaging data were present for 437 participants (age 69–71). Regression analyses tested relationships between metabolite measures—modules and hub metabolites—and imaging outcomes. Hub metabolites were defined as metabolites that were highly connected within significant (pFDR APOE genotype, lipid medication use, childhood cognitive ability, and social factors. Finally, associations were tested between AD polygenic risk scores (PRS), including and excluding the APOE region, and metabolites and modules that significantly associated (pFDR N = 1638). Results In the fully adjusted model, three lipid modules were associated with a brain volume measure (pFDR ß = 0.14, 95% CI = [0.055,0.23]), one in several fatty acid pathways (whole-brain volume: ß = − 0.072, 95%CI = [− 0.12, − 0.026]), and another in diacylglycerols and phosphatidylethanolamines (whole-brain volume: ß = − 0.066, 95% CI = [− 0.11, − 0.020]). Twenty-two hub metabolites were associated (pFDR Conclusions Our findings highlight key metabolites, with functions in membrane integrity and cell signalling, that associated with structural brain measures in later life. Future research should focus on replicating this work and interrogating causality.

Headstarting, in which eggs are taken from the nests of wild birds, incubated artificially and the chicks reared in captivity before release to the wild, has been conducted since 2012 on the subarctic breeding grounds of the Critically-Endangered Spoon-billed Sandpiper Calidris pygmaea in an attempt to increase the production of fledged juveniles. We used resightings of individually-marked head-started juveniles after they had moved away from the natal release site to assess differences in post-release survival of birds released at the same site on the same date in relation to differences in the age at which they were released. There was an unexpected significant tendency for survival to decrease with increasing age at release, both for survival beyond the period immediately after release and also to one year old. This effect of age at release is likely to be causal because multiple logistic regression analyses indicated that potential confounding effects of year of release and hatching date did not have statistically significant effects when included in models along with age at release. The mechanism underlying the effect of age at release is unknown, but possible explanations include increased stress or risk of disease or injury of individuals kept captive for longer periods. Our results suggest that releasing all juveniles at the typical age at fledging of wild birds (ca. 17 days) would improve post-release survival substantially. Possible further research could include experiments in which groups of juveniles matched for hatching date and other covariates are released at different ages in the same year and correlative studies of the condition and health of captive juveniles in relation to previous avicultural interventions and the duration of time in captivity.

For ground-nesting and colonial bird species, predation of eggs and chicks can exert a strong negative effect on population growth and recovery. For declining populations of waders breeding on lowland wet grassland, predation management tools are available to reduce the impacts of mammalian predators (e.g. lethal control, exclusion), but potential solutions are limited when raptors, which are often themselves protected by law and not easily excluded, are responsible for predation. Diversionary feeding (DF), where predators are provided with alternative food to replace the target prey species in their diet, has been tested successfully by providing food close to nesting raptor pairs to target specific individuals. Where many individuals are involved in predation at a single prey colony, or where locating or accessing nests is difficult, provisioning DF close to the focal prey colony may be a more practical solution. Here, we test the efficacy of providing DF in this way to reduce predation by red kites, a reintroduced and increasingly abundant protected raptor in the UK, on the chicks of northern lapwing, an internationally declining wader species. We conducted a five-year field experiment, comparing kite predation rates and breeding productivity of lapwings in years before, during and after DF. Rates of kite predation on lapwing chicks were substantially and significantly reduced in DF years, due to the successful elimination of a May-June peak in kite predation by DF which coincided with the kite chick provisioning and lapwing chick rearing periods. These annual reductions in kite predatory strike rates were concurrent with marked increases in overall annual lapwing productivity, which more than doubled on average in DF years, and were on a scale sufficient to facilitate lapwing population recovery. DF attracted other potential predators of lapwing eggs and chicks, and more kites were attracted to feeding stations than were initially targeted by DF, but neither had any measurable impact on lapwing breeding success during DF years or after its cessation. With increasing populations of many raptor species, predator-prey conservation conflicts are expected to increase. DF proved to be a highly effective predation management tool for a high-density wader colony on lowland wet grassland where intensive kite predation limited breeding success. Although evaluation of the effects of using DF continuously over several years is needed, targeting multiple predator individuals close to the focal prey of conservation concern may be an important predation management tool where accessing individual raptors at nest sites is impractical.

1. Understanding how to allocate land for the sustainable delivery of multiple, competing objectives is a major societal challenge. The land sharing-sparing framework presents a heuristic for understanding the trade-off between food production and biodiversity conservation by comparing region-wide land use scenarios which are equivalent in terms of overall food production. 2. Here, for two contrasting regions of lowland England (The Fens and Salisbury Plain), we use empirical data and predictive models to compare a suite of spatially explicit scenarios reflecting the full range of the sharing-sparing continuum, including mixed scenarios which combine elements of both sharing and sparing. We evaluate a range of outcomes (bird populations, global warming potential (GWP), nitrogen and phosphorus pollution and outdoor recreation), in order to identify approaches to regional land use planning with the potential to deliver multiple societal benefits. 3. Land-sharing scenarios (which reduce the dominance of productive agricultural land in farmed areas and the area of larger unfarmed areas) result in negative outcomes, particularly for birds and GWP. In contrast, many land-sparing scenarios (including mixed scenarios which increase the area of lower-yield farmland alongside larger unfarmed areas) resulted in improvements in all or most outcomes, although for recreation and nutrient export differences between scenarios were modest. 4. Importantly, environmental outcomes also depended on the spatial arrangement of spared land, the types of natural or semi-natural habitat promoted on spared land, whether some lower-yield farmland is delivered alongside larger unfarmed areas, and the overall region-wide food production target. 5. Policy implications. Our study suggests that the negative environmental consequences of high-yield farming (at least those considered here) can be outweighed by its potential land-sparing benefits. However, for high-yield agriculture to realise its full land-sparing potential, explicit policies such as certification or payments for ecosystem services are required to ensure sustainable yield growth alongside habitat conservation. Our study also highlights the importance of mitigating projected increases in food demand.

There are significant negative effects of exposure to spent lead ammunition on wildlife and human health. A joint statement was issued by nine UK shooting and rural organisations on 24th February 2020 intended to encourage a voluntary transition to non-lead shotgun ammunition within five years “in consideration of wildlife, the environment and to ensure a market for the healthiest game products”. We dissected carcasses of wild-shot common pheasants Phasianus colchicus sold or offered for human consumption in Britain in the shooting season between 1st October 2020 and 1st February 2021 to recover shotgun pellets. The principal metallic element composing one pellet from each bird was identified using inductively coupled plasma atomic emission spectrometry. The results showed that 99% of the 180 pheasants from which shotgun pellets were recovered had been killed using lead shotgun ammunition, compared with 100% in a much smaller study conducted in the 2008/2009 shooting season. We conclude that the shooting and rural organisations’ joint statement, and their subsequent promotional actions, have not yet had a detectable effect on the ammunition types used by shooters supplying pheasants to the British game market., The Royal Society for the Protection of Birds, Waitrose & Partners and Lincolnshire Game contributed to the costs of materials and reagents for the study.

After suffering a massive decline (~ 99%) in numbers caused by feeding on livestock carcasses containing the nephrotoxic drug diclofenac, critically endangered Gyps vultures now persist in low numbers in the Indian subcontinent. Most are concentrated near National Parks, likely due to availability of wild carcasses free from toxic veterinary drugs. Quantification of vulture diets is critical to test this hypothesis. We describe a validated “field-to-benchtop-to-desktop” metabarcoding workflow for assessing species- and sex-specific diet of these obligate scavengers from non-invasively collected faecal samples. Seven metabarcodes were designed to simultaneouslsy identify the vulture species, sex and diet. Amplicons generated from multiplex PCRs were indexed and sequenced on an Illumina Miseq platform. We included controls and three replicates per sample to establish a series of non-arbitrary thresholds to filter the sequence data and eliminate cross-contamination, PCR/sequencing errors and false positives. This strategy enabled identification of species and sex for all samples and dietspecific sequences with high taxonomic resolution for 97% of samples. Just four (two for diet, one each for vulture species and sexing) metabarcodes were sufficient to meet the objectives. This preliminary analysis suggests that domestic livestock is the most frequently consumed diet item across samples from inside and outside protected habitats. Our method provides a rapid and reliable tool for describing large-scale variation in consumption of domestic versus wild species in the diet of these scavengers, paving the way for a better understanding of the role protected areas play in persistence and recovery of the remaining Gyps vultures in the wild.

Population declines of the critically endangered Sociable Lapwing are probably due to high mortality along its migration routes or on its wintering grounds, both of which are very poorly known. We therefore undertook a long-term study of the species’ movements using satellite tagging, colour-ringing, targeted field surveys and a database of historical and recent sightings. We identified two migration flyways from the breeding grounds in Kazakhstan; a longer western route (c. 5,200 km) west through southern Russia, then south through the Caucasus to wintering areas in Saudi Arabia and eastern Sudan, and a shorter eastern route (c. 2,800 km) south through Turkmenistan and Uzbekistan to wintering areas in Pakistan and north-western India. The migration strategy is characterised by infrequent long-distance movements followed by often lengthy stopovers in a small number of staging areas that are used consistently across years, and by high individual and low between-individual consistency in spatial and temporal patterns of movement. At least four main autumn stopover areas and one additional spring stopover area were identified along the western route, but only one autumn and one spring staging area along the eastern route. There was no relationship between latitude or longitude of breeding and the migration route used, and the same breeding colonies could contain breeding adults and produce chicks of both flyway populations, suggesting that no clear migratory divide exists within the breeding range. Sociable Lapwings spend around a third of the year on their breeding grounds, a third on their wintering grounds and a third moving between them. Birds were highly faithful to passage and wintering sites, but showed low fidelity to breeding sites. Stopover areas and wintering sites are usually located at the interface of dry steppe-like or desert habitats and agriculture, particularly irrigated cropland along rivers. This species selects agricultural habitats throughout its entire life cycle, and its heavy reliance on some of the world’s most anciently cultivated regions suggests that this synanthropic relationship may have evolved over millennia. The recent emergence of irrigated agriculture in the deserts of Arabia allows birds using the western route to winter far north of their previous wintering range and maybe to spread into new wintering areas along the coasts of the Arabian Gulf. The concentration of large numbers of birds at a small number of traditional stopover areas offers the opportunity to quantify the global population size, which we estimate at around 24,000 individuals (95% CL: 13,700 – 55,560). However, it also makes the species particularly vulnerable to hunting and small-scale habitat change. Illegal hunting along the western flyway is identified as the most likely driver of the species’ decline.

A widely-used method for the estimation of numbers of deaths of wildfowl caused by the ingestion of spent lead gunshot pellets depends entirely upon field experiments on wild Mallards conducted 70 years ago in the USA by Frank C. Bellrose. The validity of this method has recently been questioned because of the simple method used to estimate the annual mortality caused by the experimental administration of lead gunshot and because the administration of shot appeared to increase the risk that treated birds would be shot by hunters, which might bias the mortality estimates. In this paper, we report a re-analysis of Bellrose’s data using a different method which removes the possible effect on mortality estimates of differences in the proportion of birds killed by hunters in the first year after release. Our results indicate that the additional mortality caused by the administration of lead gunshot in the first year after treatment was substantial and dependent upon the dose of gunshot administered, to a similar extent as was found by Bellrose.

The spoon-billed sandpiper Calidris pygmaea, a migratory arctic-breeding shorebird, is one of the world’s rarest birds and its population has undergone a large decline in recent decades. We conducted surveys at its most important known wintering area in the Upper Gulf of Mottama in Myanmar to estimate recent (2009 – 2016) changes in its numbers there. The total number of small shorebirds present in the Upper Gulf was counted and the proportion of them that were spoon-billed sandpipers was estimated from sample scans. These two quantities were multiplied together to give the estimated number of spoon-billed sandpipers in each of four years. Total numbers of combined small shorebird species tripled from 21,000 to 63,000 between 2009 and 2016, coincident with efforts to reduce hunting pressure on waterbirds. However, the proportion of small shorebirds that were spoon-billed sandpipers declined and their estimated absolute numbers fell by about half from 244 to 112 individuals. It is probable that loss of intertidal habitat and shorebird hunting elsewhere on the migration route of the spoon-billed sandpipers wintering at Mottama is causing a continued decline, though this is occurring at a less rapid rate than that recorded from Arctic Russia before 2010. The number of spoon-billed sandpipers wintering on the Upper Gulf of Mottama remains the highest single-site total for this species from any known wintering site. Preventing any resurgence of illegal shorebird hunting and ensuring long-term protection of the intertidal feeding habitats and roost sites in the Gulf are high priorities if extinction of this species is to be averted.

Voluntary sustainability standards have expanded dramatically over the last decade. In the agricultural sector, such standards aim to ensure environmentally and socially sustainable production of a variety of commodity crops. However, little is known about where agricultural certification operates and whether certified lands are best located for conserving the world's most important biodiversity and benefiting the most vulnerable producers. To examine these questions we developed the first global map of commodity crop certification, synthesizing data from over one million farms to reveal the distribution of certification in unprecedented detail. It highlights both geographical clusters of certification as well as spatial bias in the location of certification with respect to environmental, livelihood and physical variables. Excluding organic certification, for which spatial data were not available, most certification of commodity crops is in tropical regions. Certification appears to be concentrated in areas important for biodiversity conservation, but not in those areas most in need of poverty alleviation, although there were exceptions to each of these patterns. We argue that the impact of sustainability standards could be increased by identifying places where it would be most beneficial to strengthen, consolidate, and expand certification. To achieve this, standards organizations will need to undertake more rigorous collection of spatial data, and more detailed analysis of their existing reach and impacts, with attention to potential trade-offs between different objectives. Efforts to promote spatial prioritization will require new partnerships to align specific conservation aims with the interests and capabilities of farmers.

Land sparing has been proposed as a strategy to reconcile biodiversity conservation with agricultural production, with empirical studies on five continents indicating that most species would benefit if food demand was met through high-yield farming combined with the protection or restoration of natural habitat. Most such studies come from landscapes covered by large areas of natural habitat and without a long history of intense human modification. However, much of Europe consists of human-dominated landscapes, where biodiversity responses to land sparing may differ. To test this, we use estimates of bird population density in different (semi-)natural habitats, and forecasts of population density in farmland habitat, to assess the future consequences for birds of land-sparing scenarios in the United Kingdom. Our scenarios predict that whilst up to 18 of the 156 species assessed (predominantly farmland associated species) might decline in UK conservation status under land sparing, up to 35 UK bird species (mainly woodland and wetland species) might improve in status. This contrasts with a maximum of eight species likely to improve in conservation status without land sparing, with up to seven species deteriorating. Combining land sparing with demand management measures (reducing food waste and the consumption of animal products) led to more positive population changes under all scenarios. Synthesis and applications. Land sparing has the potential to benefit UK bird populations in aggregate but would likely have negative impacts on farmland bird species. These findings are likely to be applicable across human-dominated landscapes beyond the UK, though effects on other taxa, implementation mechanisms and the sustainability of higher yields all require careful consideration.

The Critically Endangered Spoon-billed Sandpiper Calidris pygmaea breeds in arctic and subarctic Russia and migrates to winter on coastal mudflats in south-east Asia. Its world population is probably about 700 individuals. We report Lincoln-Petersen closed-population estimates of the number of Spoon-billed Sandpipers at Tiaozini, a coastal site in Jiangsu Province, China, based upon resightings and scan surveys of individually-marked leg-flagged birds. Surveys were conducted in September-October, when adult Spoon-billed Sandpipers are moulting their primary feathers and long-distance movements are unlikely. We estimated that 220 birds were present at Tiaozini in 2017 and 224 in 2018. Nearly all of them were adults (one-year old or older), so about 40% of the world population of this age class was estimated to be present. Hence, protection of the mudflats and roost sites at Tiaozini is of global importance for the conservation of the Spoon-billed Sandpiper.

Two solutions, at opposite ends of a continuum, have been proposed to limit negative impacts of human agricultural demand on biodiversity. Under land sharing, farmed landscapes are made as beneficial to wild species as possible, usually at the cost of lower yields. Under land sparing, yields are maximized and land not needed for farming is spared for nature. Multiple empirical studies have concluded land-sparing strategies would be least bad for wild species provided land not needed for agriculture was indeed spared for nature, but the possibility of imperfections in the delivery of land sparing has not been comprehensively considered.

SummaryPopulations of the White-rumped VultureGyps bengalensis, Indian VultureG. indicusand Slender-billed VultureG. tenuirostrisdeclined rapidly during the mid-1990s all over their ranges in the Indian subcontinent because of poisoning due to veterinary use of the non-steroidal anti-inflammatory drug diclofenac. This paper reports results from the latest in a series of road transect surveys conducted across northern, central, western and north-eastern India since the early 1990s. Results from the seven comparable surveys now available were analysed to estimate recent population trends. Populations of all three species of vulture remained at a low level. The previously rapid decline of White-rumped Vulture has slowed and may have reversed since the ban on veterinary use of diclofenac in India in 2006. A few thousand of this species, possibly up to the low tens of thousands, remained in India in 2015. The population of Indian Vulture continued to decline, though probably at a much slower rate than in the 1990s. This remains the most numerous of the three species in India with about 12,000 individuals in 2015 and a confidence interval ranging from a few thousands to a few tens of thousands. The trend in the rarest species, Slender-billed Vulture, which probably numbers not much more than 1,000 individuals in India, cannot be determined reliably.

Climate may influence the distribution and abundance of a species through a number of demographic and ecological processes, but the proximate drivers of such responses are only recently being identified. The Ethiopian Bush-crow Zavattariornis stresemanni is a corvid that is restricted to a small region of southern Ethiopia. It is classified as Endangered in the IUCN Red List of globally-threatened species. Previous work suggested that this range restriction is almost perfectly defined by a climate envelope that is cooler than surrounding areas, but the proximate mechanism remains unexplained. The heavily altered habitats which the species inhabits are widespread across Africa, and recent work has shown that the Bush-crow is behaviourally adaptable and has a catholic diet. We assess whether its enigmatic distribution can be explained by behavioural responses to the higher temperatures that surround its current range. Using environmental niche models and field observations of thermally-mediated behaviour, we compare the range restriction and behavioural thermoregulation of the Ethiopian Bush-crow (a starling-like corvid) with those of two sympatric control species that are similar in size and ecology, but have much larger ranges that include hotter environments. The White-crowned Starling Lamprotornis albicapillus and Superb Starling L. superbus occupy similar habitats to the Ethiopian Bush-crow and all three frequently forage together. We found that the Bush-crow’s range is limited primarily by temperature, with a secondary effect of dry season rainfall, whereas the ranges of the two starling species are better predicted by wet season rainfall alone. Bush-crows exhibited panting behaviour and moved into the shade of trees at significantly lower ambient temperatures than did the starlings, and their food intake declined more steeply with increasing temperature. These results suggest that the Bush-crow’s limited geographical range reflects an inability to cope with higher temperatures. This suggests that a species’ response to climate change might not be easily predicted by its ecological generalism, and may represent an inherited debt from its evolutionary history.

The loss of carbon stocks through agricultural land-use change is a key driver of greenhouse gas emissions [1, 2, 3, 4], and the methods used to manage agricultural land will have major impacts on the global climate in the 21st century [4, 5, 6, 7, 8, 9]. It remains unresolved whether carbon losses would be minimized by increasing farm yields and limiting the conversion of natural habitats (“land sparing”), or maximizing on-farm carbon stocks, even at the cost of reduced yields and therefore greater habitat clearance (“land sharing”). In this paper, we use field surveys of over 11,000 trees, in-depth interviews with farmers, and existing agricultural data, to evaluate the potential impacts of these contrasting approaches, and plausible intermediate strategies, on above-ground carbon stocks across a diverse range of agricultural and natural systems. Our analyses include agroforestry and oil palm plantations in the humid tropics of Ghana; cattle ranching in dry tropical forest in Mexico; and arable cropping in temperate wetlands and forests in Poland. Strikingly, despite the range of systems investigated, land sparing consistently had a higher potential to sustain regional above-ground carbon stocks than any other strategy. This was the case in all three regions and at all plausible levels of food production, including falls in demand. However, if agricultural production increases to meet likely future demand levels, we project large decreases in above-ground carbon stocks, regardless of land-use strategy. Our results strongly suggest that maintaining above-ground carbon stocks will depend on both limiting future food demand and minimizing agricultural expansion through linking high-yield farming with conserving or restoring natural habitats.

Balancing the production of food, particularly meat, with preserving biodiversity and maintaining ecosystem services is a major societal challenge. Research into the contrasting strategies of land sparing and land sharing has suggested that land sparing—combining high‐yield agriculture with the protection or restoration of natural habitats on nonfarmed land—will have lower environmental impacts than other strategies. Ecosystems with long histories of habitat disturbance, however, could be resilient to low‐yield agriculture and thus fare better under land sharing. Using a wider suite of species (birds, dung beetles and trees) and a wider range of livestock‐production systems than previous studies, we investigated the probable impacts of different land‐use strategies on biodiversity and aboveground carbon stocks in the Yucatán Peninsula, Mexico—a region with a long history of habitat disturbance. By modelling the production of multiple products from interdependent land uses, we found that land sparing would allow larger estimated populations of most species and larger carbon stocks to persist than would land sharing or any intermediate strategy. This result held across all agricultural production targets despite the history of disturbance and despite species richness in low‐ and medium‐yielding agriculture being not much lower than that in natural habitats. This highlights the importance, in evaluating the biodiversity impacts of land use, of measuring population densities of individual species, rather than simple species richness. The benefits of land sparing for both biodiversity and carbon storage suggest that safeguarding natural habitats for biodiversity protection and carbon storage alongside promoting areas of high‐yield cattle production would be desirable. However, delivering such landscapes will probably require the explicit linkage of livestock yield increases with habitat protection or restoration, as well as a deeper understanding of the long‐term sustainability of yields, and research into how other societal outcomes vary across land‐use strategies.

Land sharing and land sparing are contrasting proposals for minimising the impacts of agriculture on wild species. Edge effects (biophysical gradients near habitat boundaries) might reduce population sizes on spared land, particularly in highly-fragmented landscapes, so might change conclusions about whether land sparing or land sharing is better for species' persistence. We assessed this possibility by modelling the population sizes of 120 Ghanaian bird species in the presence of a range of hypothetical edge effects under land-sparing and land-sharing strategies, and at different levels of habitat fragmentation and agricultural production. We found that edge effects can reduce population densities on spared land, and in highly-fragmented landscapes can - at modest levels of agricultural production combined with high edge penetration distances - cause the optimal strategy to switch from land sparing to land sharing. Nevertheless, land sparing maximised population sizes for more species in most cases tested. This conclusion was best supported for sensitive species with small global geographical ranges, which are likely to include those of greatest future conservation concern. The size of patches of spared land affected conservation outcomes: population sizes were maximised under a land-sparing strategy that spared large blocks of natural habitat of ~ 1000 or, better, ~ 10,000 ha. To effect land sparing in practice would require policies that promoted both increases in agricultural yield and the establishment or protection of natural habitats on spared land. Because the optimum scale of patches of spared land for edge-sensitive species is generally larger than the size of individual farms, policies that facilitate coordinated action by farmers or other land managers might be required.