Ecology

With agriculture the main driver of the habitat loss and degradation that underpin the global biodiversity crisis1, governments worldwide have implemented policies to lessen farming’s impact on the environment. Meanwhile, landowners, organizations interested in the financing of biodiversity conservation and certain non-governmental groups, including conservation bodies, have been pushing for land-use changes that benefit nature.However, numerous studies show that some of today’s most popular conservation policies are doing little to help those species most affected by farming. What’s more, by reducing how much food is produced per unit area (yield), they are driving up food imports and thereby having an impact on wildlife overseas.One of us (I.B.) has advised seven UK secretaries of state for the environment over the past decade; the other (A.B.) has, for two decades, led empirical work investigating how to reconcile food production with biodiversity conservation. In our view, there are many reasons for the disconnect between the science and policy.Part of the problem is that, especially in Europe, the owners of the biggest, and often richest, farms stand to gain the most from current policies2. Thousands of influential individuals are lobbying to maintain the status quo in agricultural policy.
EU climate plan sacrifices carbon storage and biodiversity for bioenergy
A more fundamental and massively under-recognized problem is that both government policy and much academic debate have focused too narrowly on the local effects of a given approach, rather than on its overall (often long-distance) impacts. Indeed, this tendency to ignore downstream consequences — even as much better tools and data become available to track and quantify such impacts — is causing significant problems across a range of conservation and climate policies.It doesn’t have to be this way. Modelling approaches are now being developed so that the information that is already available can significantly improve decision-making around agriculture and the environment. Using the wealth of evidence from research to guide agricultural policy could better reconcile conservation with people’s need for food. It could also pave the way for the evidence-based decision-making that is urgently needed across a broad sweep of environmental challenges.In vogueIn response to the biodiversity crisis, the European Union, the United Kingdom, Japan, Mexico and other regions and countries are increasingly devoting resources to what seem to be environmentally friendlier ways to use land.Since it was created in the 1960s, the Common Agricultural Policy (CAP) has been the EU’s most expensive policy. More than one-fifth of the CAP budget — currently set at €56 billion (US$60 billion) a year — is available for ‘environmental improvement’, and most of that is funnelled into ‘land-sharing’ schemes.

A wildflower margin next to a harvested Dutch wheat field — an example of land sharing.Credit: Getty

Land sharing uses a variety of approaches to increase biodiversity in farmland. Interventions include reducing the use of pesticides and fertilizers, adopting more-diverse cropping regimes and creating small-scale habitats such as unsprayed field margins and small patches of woodland.Land sharing increases the populations of relatively common animals and plants, such as skylarks, field poppies and the more widespread butterflies. And highly targeted interventions can help some vulnerable species. But in the main, land sharing does little for those most specialized or threatened species that need large stretches of contiguous non-farmed habitat, such as the many birds, invertebrates, plants and fungi dependent on old-growth forest. In fact, farmland biodiversity has continued to decline under land-sharing policies, with the UK population of corn buntings (Emberiza calandra), for example, falling by 83% since the late 1960s3.What’s more, taking land out of agriculture without lowering food demand or raising yields elsewhere in a country increases the need for imports, which means more harm to biodiversity and natural habitats farther away4. Indeed, the EU’s crop imports in the 25 years up to 2014 generated more than 11 million hectares of habitat destruction5 — an area larger than Cuba — in some of the world’s most biodiverse ecosystems, including those in Brazil and Indonesia (see ‘Offshoring the problem’). In 2020, even the EU’s official auditors declared the CAP a failure in terms of its environmental policies (see go.nature.com/45sasew).

Source: Ref. 5

Besides land sharing, two approaches have been gaining popularity in recent years, but each brings similar problems.Some conservation groups and landowners have increasingly advocated for rewilding, in which large, contiguous areas of land are taken out of farming. Rewilding can benefit species that are locally vulnerable or endangered. For example, efforts to rewild 400 hectares at Ken Hill in eastern England have created a refuge for beavers, which have been extinct in the United Kingdom since the sixteenth century. Such rewilding initiatives are obviously of value to national biodiversity. However, assessments of the benefits rarely consider offshore damage. As with land sharing, unless people change their diets or eat less, or yields are increased in areas that are still farmed, the removal of land from productive agriculture will increase the demand for food imports, and so damage biodiversity elsewhere6.
Europe’s Green Deal offshores environmental damage to other nations
Organic farming has been around for longer. In the past few years, both the EU and Japan have committed to converting one-quarter of farmland to organic production by 20305 and 2050 (see go.nature.com/43qycet), respectively. Although some farmland species are likely to benefit from the removal of manufactured fertilizers and modern pesticides, the approach will do little to help those that require contiguous natural habitats. Furthermore, organic production drastically lowers yields. Sri Lanka’s recent food crisis has been attributed in large measure to the government’s (now abandoned) attempt to convert the country to organic farming (see go.nature.com/3p2kgfq). And estimates suggest that a wholesale switch to organic farming across England and Wales would cut food-calorie output by 40%7. Again, this would lead to greater demand for food imports, and so increase pressure on production and hence on biodiversity around the world.What the science saysFortunately, another approach could bring substantial benefit to both local and global biodiversity (see ‘Helping or harming nature?’). Land sparing involves lumping habitat patches together into larger blocks, alongside the adoption of lower-impact ways to boost yields in the areas that are still farmed. Together, these two actions can make space for better habitat protection locally without displacing production overseas.

Source: data from multiple studies; see ref. 9 for a review.

Choosing which areas to put aside for nature requires an understanding of the consequences of land-use change — for food production, but also for greenhouse-gas fluxes, hydrological regimes, access to recreation, the spread of pollutants and so on. But, in relation to biodiversity, larger habitat blocks — which are less affected by the drier, often windier and more variable conditions at the margins — can, for their size, hold larger populations of those species that favour more-natural habitats. The greater diversity of environments that arise in larger areas also supports a greater diversity of specialist species8.For areas that are still farmed, an array of techniques can help producers to raise crop and livestock yields sustainably. Options include providing animals in extensive grazing systems with greater access to improved pasture, water sources and modern veterinary care; using genomic screening and gene editing to accelerate animal and crop breeding; growing high-value crops such as salad vegetables and herbs in trays that are stacked vertically; using native plants to redistribute pests away from crops; and using ‘recirculating’ aquaculture systems to produce high-value products such as king prawns.Over the past decade or so, field studies in India, Ghana, Uganda, Kazakhstan, Mexico, Colombia, Brazil and Uruguay, as well as in Poland and the United Kingdom, have all concluded9 that (for the same overall food output), high-yield farming combined with land sparing results in larger populations of most wild species than does land sharing (see ‘Winners and losers’). These findings, across more than 2,000 species of bird, plant and insect, are especially pronounced for those species with narrow geographical distributions, which make them particularly vulnerable.

Source: data from multiple studies; see ref. 9 for a review.

Last year, a study that surveyed UK farmers to establish what actions they would take, for what payment, found that delivering the same biodiversity outcomes for birds through land sparing would cost the taxpayer just 48% of the cost under land sharing; the impact on domestic food production would also be 21% lower under land sparing10. Thus, for the same budget, sparing seems to provide much greater biodiversity gains than does sharing.Other research has shown that, in comparison to land sharing, a land-sparing approach can deliver significantly greater co-benefits, such as the removal and storage of greenhouse gases and the provision of recreational areas11. And calculations for the United Kingdom and Poland show that blended approaches, which combine spared land with shared farmland and high-productivity agricultural land, do even better in these countries than does pure sparing, and greatly outperform both current farming systems and pure sharing approaches9.Because sparing increases yields on the land still being farmed (and this is more easily achieved wherever there are big gaps between current and potential yields), these approaches can help to address food-security concerns10. Also, the need for both agricultural innovation and, in many areas, habitat restoration means that land sparing need not adversely affect rural employment12.Of course, yield increases do not inevitably lead to more land being available for conservation. Critics of land sparing point out that gains in yield could simply lead to rebound effects, with less land being taken out of farming than expected, or even to more land being converted to farmland because of the promise of greater profits13.

Aquaculture techniques can raise yields sustainably, such as at this prawn farm in La Cruz, Mexico.Credit: Susana Gonzalez/Bloomberg via Getty

The evidence suggests, however, that although individual food producers generally use yield-intensifying practices to boost their incomes, overall land use tends to decrease13. These benefits could be increased by policies and subsidies crafted to dampen rebound effects; farmers could be given support for innovation in exchange for reducing the area under cultivation. A reassessment of data for birds and trees in Ghana and India shows that sparing would still outperform sharing even when policies to limit rebound effects are not put in place9.A matter of focus So, given that land sparing could benefit more biodiversity at lower cost than can other strategies, and deliver an array of co-benefits, why is it not the dominant approach today?The influence of the ‘big farm’ lobby in maintaining the status quo in agricultural policy is one widely cited reason14. The chief approach to allocating subsidies — using flat-rate payments per hectare of shared land — disproportionately benefits the largest (and often richest) farms. As a result, in the United Kingdom, 12% of farms take 50% of all taxpayer subsidies, whereas half of all farms share just 10% of those subsidies2 (see ‘The devil is in the detail’).
The devil is in the detail

Subsidies are used to persuade landowners to make changes to benefit nature, but subsidy design determines how effective they are.
Flat-rate subsidies pay farmers a set amount per hectare for conservation. This common approach channels the majority of subsidies towards the largest, and often richest, farms. Such schemes also fail to incentivize farmers to do more than the minimum stipulated in policy documents and often penalize those who go further. For example, if UK farmers plant trees on their land (and do not fell them at least every ten years), that land is removed from the tax exemptions accorded to ‘productive’ farmland (see go.nature.com/468wrzb).
A better approach would be to pay rewards not for the amount of land farmers devote to ‘nature improvement’, but for the expected outcomes. For this, farmers would be free to propose actions to address a specific environmental problem and to state what payments they would accept in return. Modelling is then used to predict benefits. By comparing these expected outcomes with the costs required by each farmer, decision makers can choose those farms and actions that deliver the best value for money19.

In our view, however, a more fundamental and much less recognized problem confounds the application of scientific research to environmental policy — and not just in relation to agriculture.The ‘focusing illusion’15, proposed by the Nobel-prizewinning psychologist and economist Daniel Kahneman, is the psychological phenomenon that focusing on one effect of a change tends to diminish our perception of all the other possible effects of that change. The literature is replete with studies of the effects of a change in terms of a single (often local) measure: biodiversity or carbon storage, nitrogen pollution or flooding, food production or recreation. Fewer assessments exist of multiple outcomes or of system-wide impacts.Historically, part of the challenge has been a lack of data and understanding. Even studies considering the plural effects of a change in how land is used have often been locally or nationally focused, largely because the modelling work linking the change to broader economic and environmental effects hasn’t been available16.Global-trade modelling, however, is now enabling researchers to obtain a much fuller picture of the economic and environmental effects of both policy interventions and business investments17.
Food systems: seven priorities to end hunger and protect the planet
Over the past five years or so, there has also been more research aimed at designing tools that allow policymakers and other stakeholders to understand the wider consequences of a change in land use. As an example, one of us (I.B.) is involved in a project to examine the full effects of the UK government’s decision, in 2020, to fund substantial increases in national woodland cover to remove greenhouse gases18. The Natural Environment Valuation Online tool (www.leep.exeter.ac.uk/nevo), which will be used in this project, combines information from multiple disciplines to show decision makers how such a change in the way land is used will help to satisfy England and Wales’s net-zero-emissions commitments, benefit biodiversity, improve access to recreation and so on. The tool also shows the impact of changes in land use on domestic food production, which can then be linked to changes in land use and biodiversity globally.The goal of research on system-wide impacts should not be to obtain ever more detailed sources of information about all the possible effects of a proposed policy change. Rather, analyses should be extended to the point at which the costs of collecting and analysing more data begin to exceed the benefits of more-informed decision-making. Such interdisciplinary studies and approaches that focus on the needs of decision makers must become the norm.The stakes are too high for policymakers to continue to ignore the promise of land sparing when so much research demonstrates that it is a much more effective approach than many of the strategies being deployed. This issue has become even more urgent since last December, with the adoption of the Convention on Biological Diversity’s goal of protecting 30% of the planet’s land and oceans by 2030. Exactly how this 30% will be put aside (as large contiguous natural habitats or as a multitude of fragments), and how the world’s growing demand for food and other goods will be met from the unprotected remainder of Earth’s surface, will in large part determine the biodiversity consequences of this ambitious commitment.Yet the story about land sparing carries an even broader message: unless researchers and policymakers assess the overall, global effects of interventions aimed at addressing biodiversity loss, climate change and environmental degradation, poor decisions that are unsupported by the data will at best under-deliver, and at worst exacerbate these existential threats. More

Between now and September, Nature will be publishing a special series of editorials covering each of the 17 Sustainable Development Goals.Credit: Stanislav Kogiku/SOPA Images/LightRocket via Getty

Many people would be unable to name even one of the 17 United Nations Sustainable Development Goals (SDGs), which are at the heart of an international project that aims to end poverty and achieve equality while protecting the environment. From this week, to help raise awareness, we at the Nature Portfolio journals will intensify our ongoing efforts to publish research and commentary on the SDGs.The SDGs and their 169 associated targets are among humanity’s best chance of dealing with global crises, from climate change to economic hardship. World leaders agreed the goals in 2015 and set a 2030 deadline to achieve them. This year, at the half-way point, it looks likely that none of the goals and just 12% of the targets will be met.In September, world leaders will gather in New York City to come up with a rescue plan. And between now and then, Nature will be publishing a series of editorials focusing on the different SDGs, covering what has and hasn’t been achieved, what can be done to improve matters, and the part the global scientific community has to play.The failure to meet even one of the SDGs is not for want of trying. Worldwide, researchers have been aligning their work with the SDGs, along with other global efforts such as UN conventions on climate change and biodiversity loss. Unfortunately, fracturing geopolitics is hindering international cooperation. In addition, there is limited cooperation and coordination across topics and between disciplines.There is a need to give more consideration to complementarities and trade-offs between the different SDGs. For example, action to develop affordable and clean energy (SDG7) to tackle climate change (SDG13) can have negative local effects on biodiversity (SDGs 14 and 15) through the construction and operation of facilities such as wind and solar farms. And although finance for coal-fired power is an effective way to create work and economic growth (SDG8), it is bad news for health and well-being (SDG3), as well as for the environment. The knowledge of these trade-offs is often given insufficient consideration in policymaking.
Do the science on sustainability now
Last week, an independent group of science advisers to the UN proposed a way forwards. Their 2023 Global Sustainable Development Report (GSDR) summarizes where the SDGs are failing, and what can be done to rescue them. It reiterates the need for transformational change to get the world onto a sustainable path. Crucially, it recognizes the interconnectedness of the goals and targets.Like its predecessor, published in 2019, the report recategorizes the SDGs into six “entry points”: human well-being and capabilities; sustainable and just economies; sustainable food systems and healthy nutrition patterns; energy decarbonization with universal access; urban and peri-urban development; and global environmental commons. To progress on human well-being, for example, the report recommends scaling up investment in primary health care and ensuring access to lifesaving interventions; accelerating enrolment in secondary education; and increasing investment in water and sanitation infrastructure.The authors recognize that the path to sustainability must also include abolishing unsustainable practices, while taking into account the economic and social pain that this can cause. For example, increasing the availability of renewable energy won’t, on its own, tackle climate change: fossil fuels must also be phased out. As we wrote last week (Nature 618, 433; 2023), there is active resistance to this move and a genuine need to support affected communities, such as those that have relied on the coal industry for decades. Such scenarios don’t apply only to reaching energy and climate goals.The GSDR represents welcome progress on the ‘what’ of meeting the SDGs. It also proposes what to do on the ‘how’. The necessary transformations will be expensive, the authors say — requiring extra annual public and private investment of up to US$2.5 trillion. For efforts to succeed, new ways of governing will be required, with the creation of new institutions and the reform of old ones to put sustainability front and centre. Individual and collective action of the kind already under way will also be needed, but on a bigger scale. And people must be given the right resources and skills to complete the task. This will be especially important in low- and middle-income countries (LMICs).Implicit — and to a degree explicit — in all this is changing how science itself is done. The report argues that the actions that steer the world towards a sustainable path must be rooted in science that is multidisciplinary, equitable and inclusive, openly shared and widely trusted, and “socially robust” — in short, responsive to social context and social needs. As the authors acknowledge, for that to happen, global science needs to evolve. Knowledge needs to be more accessible than it is at present, and the production of that knowledge needs to be more open, too, recognizing, for example, the value of Indigenous and local knowledge to sustainable innovation.We know from a separate UN study published in 2021 that science in LMICs is already much more aligned with the SDGs than is science in high-income countries. And LMICs have published a much higher volume of research relating to the SDGs (see ‘Sustainability science’). The challenge is how to improve the situation in high-income nations. Widespread improvement would be truly game-changing for sustainability.

Adapted from: Changing Directions: Steering Science, Technology and Innovation towards the Sustainable Development Goals

That’s where we’ll take our cue. We’ll assess the evidence and talk to researchers about the state of play on the SDGs, and explore questions that researchers can help to answer. Right now, a sustainable future remains as far away as ever. If there’s even a small chance that we can still achieve the SDGs by 2030, we need to seize it with both hands. As so many have already said, there is no planet B. More

Hammerhead sharks (Sphyrna mokarran) are critically endangered and would benefit from conservation efforts.Credit: Alex Mustard/Nature Picture Library

Disputes over how to finance conservation of the world’s plants and animals have resurfaced between countries — threatening their ability to meet goals laid out in a historic plan signed late last year, sources have told Nature.At the COP15 biodiversity summit in Canada in December, more than 190 countries agreed to the Kunming-Montreal Global Biodiversity Framework, a deal including targets such as nations protecting and restoring 30% of the world’s land and seas by 2030. To ensure that all countries — particularly low- and middle-income nations (LMICs) — can meet these targets, those that signed the deal agreed to establish a trust fund by the end of this year and that, by 2030, wealthy nations should collectively be contributing US$30 billion per year.Several times during those negotiations, however, arguments erupted and threatened to derail the deal. The disputes are now rearing their heads again.A showdown loomsDuring COP15, LMICs that are rich in biodiversity called for a new, independent fund for species conservation. The current fund, run by the Global Environment Facility (GEF) within the World Bank in Washington DC, is difficult to access and slow to distribute funds, LMIC representatives said.
Nations forge historic deal to save species: what’s in it and what’s missing
But high-income nations, including some of those in the European Union, disagreed, and eventually it was decided that a newly established fund would be run by the GEF — although the deal set out provisions to continue discussions about an independent biodiversity fund.With the approach of a 26–29 June meeting, at which the GEF is set to start the process of establishing the biodiversity trust fund, fissures have appeared that threaten to delay the proceedings, according to sources involved in the discussions, who asked not to be named to maintain diplomacy.At the upcoming meeting, GEF council members — including representatives from 14 high-income countries and 18 LMICs — are slated to review a proposal, posted to the GEF’s website, to establish the fund with at total of at least $200 million from at least three donors by December. But sources say that donor countries are reluctant to agree on any initial budget for the GEF, preferring to set up the trust fund first and then discuss funding pledges. LMICs, on the other hand, say that the initial amount proposed is not enough. Researchers have suggested that the amount needed to fully safeguard and restore nature is approximately $700 billion.
Can the world save a million species from extinction?
Brian O’Donnell, the director of Campaign for Nature, a conservation advocacy group based in Durango, Colorado, says that the success of the framework depends on donor countries making good on their pledges to increase biodiversity funding. In addition to agreeing to contribute $30 billion annually by 2030, wealthy countries said that they would help to find $200 billion per year from private and public sources by 2030. But the countries have not yet started to deliver on these promises.“We need real money from donor countries,” O’Donnell says.In a statement to Nature, a GEF spokesperson said that the facility is “optimistic” that the June council meeting will approve the trust fund, and declined to comment on ongoing disputes.Biodiversity delaysLMICs are keen to see whether establishing the trust fund in the GEF is a “genuine” move by donor countries to avoid the logistics and costs of an independent fund, allowing for faster money transfer, as they stated during COP15 negotiations, says Paul Matiku, executive director of Nature Kenya, a conservation organization in Nairobi.
Scientists warn deal to save biodiversity is in jeopardy
Daniel Mukubi, a negotiator of the biodiversity-framework deal for the Democratic Republic of the Congo (DRC) who is based in Kinshasa, told Nature that some nations are not happy and are holding out for an independent fund. LMICs don’t have an adequate say in how the GEF funds are spent, he says. The DRC and other LMICs will not agree to the trust fund until after discussions on an independent fund, he adds. “We will not give up.”These tensions could delay the trust fund’s adoption, which was planned for a GEF assembly in August, delaying biodiversity action even more — as it is, the Kunming-Montreal framework was agreed two years late, owing to the COVID-19 pandemic. Meanwhile, the clock is ticking: researchers have estimated that one million species are under threat of habitat loss because of factors such as climate change and agriculture. More

I’m Guardian of the Pipmuakan forest in the Nitassinan territory of Quebec, Canada. I act as the eyes and ears of my people, the Innu, so that we can protect the caribou (atik in the Innu language). The caribou, or reindeer (Rangifer tarandus), is sacred to the Innu. For centuries, it provided us with food, clothes and tools.In my work, I combine ancestral knowledge with new technologies. The knowledge includes how to assess the ice thickness and snow depth, and how to identify the freshness of animal tracks. Drones, satellite images and GPS are among the new technologies I use.I travel across the Pipmuakan area at least four days a week on either my quad bike or snowmobile, looking for caribou tracks and other signs of herds and their predators. I also set traps for wolves.Caribou are very sensitive, so I always avoid getting close to them. When I see new caribou tracks, I use the drone to identify their location and confirm the number of animals in the herd, whether they are male, female or both, and if there are new calves. The drone also allows me to spot herds behind dense thickets without scaring them.Logging is the main threat to this forest and to the caribou. In winter, caribou eat lichen from trees. But logging destroys the lichen, and allows wolves — the caribou’s main predator — to see their prey from afar.In this picture from the third quarter of last year, I was crossing Kakuskanus lake in a pontoon boat to reach a remote area of the forest. My grandparents drowned in this lake when their canoe overturned. For 36 years, I couldn’t visit this place. I was mourning.But in 2017 I felt an urge to protect the land and came back. A century ago, there were thousands of caribou here. Now there are fewer than 200. Without the caribou, the Innu wouldn’t have survived in this forest. Now it’s time for us to help the caribou. I want my grandchildren and the following generations to experience the richness of this forest. More

The first African cheetah introduced to India last September gazes at its new home.Credit: Press Information Bureau/PIB Photo/Alamy

The world’s first intercontinental cheetah-introduction programme hit a setback last month when it emerged that three relocated animals, and three of their cubs, had died in the space of eight months. The scientists and officials behind the 500-million-rupee (US$6 million) conservation project, which was launched with great fanfare and the support of Indian Prime Minister Narendra Modi, say they will carry on with the project. But several independent scientists question whether this is wise and the project’s long-term viability.They expressed concern that the space reserved in India for the cheetahs is too small for the intended population, and they are not sure that enough has been done to prepare or to investigate how nearby farming communities will react to the animals. “With everything we know about cheetahs in this world, it seems a bit like hit-and-miss,” says Florian Weise, an independent wildlife biologist in Berlin, Germany who relocated cheetahs between different parks in Namibia for eight years.A goal of Project Cheetah is to help conserve the vulnerable South African cheetah (Acinonyx jubatus jubatus). Only 6,517 cheetahs remain in the wild, according to the International Union for the Conservation of Nature. Cheetah populations have rebounded in semi-managed reserves in South Africa (these animals are not included in the ‘wild’ number), but conservationists say there is not enough safe, wild habitat there for them to expand into. The India project is an attempt to solve this problem. The country once hosted its own population of the Asiatic subspecies (A. jubatus venaticus), which is now critically endangered and present only in Iran.Project Cheetah officially launched last September, when 8 African cheetahs were relocated from Namibia to India; 12 more were then moved from South Africa in February. Project officers released seven into Kuno National Park, an unfenced 748-square-kilometre area that was once home to cheetahs and is now inhabited by leopards (Panthera pardus).But by late May, three of the Kuno cheetahs and three newborn cubs were dead.The deaths of the three adult cheetahs were not unexpected given the high stress of relocation, says Adrian Tordiffe, a veterinarian at the University of Pretoria in South Africa, and a consultant for India’s Project Cheetah. Indeed, the Project Cheetah action plan notes that only 50% of the animals are expected to survive. “The fact that we had multiple deaths occurring in a short space of time is not unusual in the sense that it’s the high-risk period,” Tordiffe says. “Once things stabilize, that will plateau.”Two died of organ failure, and a third died in a violent mating encounter.But the deaths of the cheetah cubs are more puzzling, says Bettina Wachter, a biologist at the Cheetah Research Project, based in Berlin. Cheetah cubs in places such as the Serengeti have only a 10% survival rate owing to predation from lions (Panthera leo) and spotted hyenas (Crocuta crocuta). But in protected reserves in Namibia, where there are few predators, their survival rate is 80%, she says. She adds that, in Kuno, which has few predators, she would expect a higher survival rate.Tordiffe was also surprised by the deaths: “I wasn’t expecting these cubs to succumb given the sort of circumstances in which they were being kept,” he says.The Madhya Pradesh forest department, which manages Kuno and is implementing Project Cheetah, said the cubs died of malnutrition and weakness.Too hastyWachter and other scientists worry that Project Cheetah was drawn up hastily, without enough preparation. Only nine months elapsed between the release of the action plan and the first animals being moved to India.But Tordiffe says it made sense to act rapidly while there was political momentum. “When you have the political will, the financial backing and the financial support for a project like this, then you do everything that you can to try and make it happen, even in a short time frame,” he says.In particular, there is debate over whether Kuno is big enough for the big cats.Cheetahs need a lot of space, even compared with larger predators such as lions and tigers (Panthera tigris). Wachter says that male cheetahs maintain a 20- to 23-kilometre distance between their territories in unfenced parks in eastern and southern Africa. This separation reduces competition — and it seems to be consistent across the species, no matter the location, she says. Given these dynamics, she calculates that Kuno can house at most eight cheetahs — five males and three females.The Project Cheetah action plan says that, with the large amount of prey at the park, it can hold 21 cheetahs.“But there is really no evidence anywhere in the world that cheetahs squeeze together when there is more prey,” Wachter says. “In the Serengeti in Tanzania, there is a lot of prey. They could come closer to each other, but they don’t.”Arjun Gopalaswamy, an independent wildlife biologist based in Bangalore, India, who has studied cheetahs in Kenya, agrees with Wachter’s assessment. “What’s so extravagantly special about Kuno that it can host that many cheetahs?” he asks.But Rajesh Gopal, chair of the Project Cheetah steering committee, says Kuno can “definitely” hold 21 cheetahs. “I don’t agree with [the critics] on that,” he says. But in describing Kuno, he includes 3,200 square kilometres of potential cheetah habitat adjacent to Kuno and 3,600 square kilomtres of nearby forested area as available range.Tordiffe points out a lack of data on cheetahs in India. “Trying to decide how many cheetahs Kuno National Park can accommodate cannot be determined by any expert,” he says. “They are basing these estimates on other systems — ones that do not exist in India at the moment.”Meanwhile, Weise questions whether enough cheetahs would survive and breed to sustain a viable population. “If you want a proper population, you need dozens, if not hundreds, of survivors. That’s a big challenge,” he says.Roaming cheetahsIndependent cheetah scientists also question Kuno’s proximity to farming communities. Translocated cheetahs in southern Africa explore thousands of square kilometres in the first 6 to 12 months after release, Weise says. “Imagine I tranquilize you, and I release you in Antarctica, and you wake up in a place that you’re not familiar with,” he says. “Any intelligent mammal will start looking around. We had records of individual animals moving between 40 and 70 kilometres in a night.”Weise and others expect that cheetahs will leave Kuno and enter the surrounding countryside. Two Kuno cheetahs have already roamed outside the park. “Almost by design, they are going to live in the farmlands,” Gopalaswamy says. “Now, there’s nothing wrong with that, but was that factored in? If they’re going to just disperse out and live with people, it’s a completely different question.”The action plan originally suggested that the animals would be restricted to the park, but Gopal says the project is preparing for roaming animals. He says that, in the next few weeks, government scientists will use remote sensing to study the 6,800 square kilometres of the park and its surrounds to find potential sites of cheetah–human conflict. “The forest department needs to create a community stewardship programme so villagers are rewarded financially for protecting the cheetah,” Gopal says. “This is not new for India,” he adds. “We have been handling tigers for the last 50 years.”Once the landscape-level threat analysis is complete, seven more cheetahs could be released by the end of this month, Gopal says.SuccessIn the long run, the success of Kuno’s cheetahs will depend on how tolerant people in the area are, Wachter says. “When the tiger and leopards are already there, whether they say, ‘OK, it doesn’t matter if we have the cheetah.’ Or whether they say, ‘This is now one carnivore too much, and we don’t want it.’”“I’m not entirely against moving them to India,” Weise says. “But if they have surplus animals and don’t know where else to put them, I’m not sure India is the best place.”Rather than introducing African cheetahs, India could focus instead on helping Iran to conserve its animals, Weise says. More

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RESEARCH HIGHLIGHT
06 June 2023

After gulls switched their focus from southern right whale mothers to calves, scientists recorded a drop in calf survival. More

The Tara during its 100,000-kilometre voyage around the Pacific Ocean.Credit: François Aurat/Tara Ocean Foundation

Scientists have known for decades that the biodiversity we know is a fraction of the biodiversity that exists. Even when it comes to perhaps the simplest measure, the number of species, researchers estimate that there could be anywhere between 3 million and 100 million species, of which some 1.7 million have been described. Every year, the names of some 10,000 new ones get added to the list.Gathering good biodiversity data can be a mission in itself, especially on marine biodiversity. One dependable source is a schooner called Tara, which celebrates 20 years at sea as a research ship this year. Tara has been to the Arctic Ocean and the Mediterranean Sea. Last week, researchers reported the results of its latest voyage, Tara Pacific, a two-year expedition across the Pacific Ocean, published in a collection of articles in Springer Nature journals (go.nature.com/45puzhk).
Epic voyage finds astonishing microbial diversity among coral reefs
Coral reefs are among Earth’s most diverse ecosystems, supporting 25% of marine life and providing services such as food, jobs and coastal protection to nearly one billion people worldwide. One region of the Pacific, the Coral Triangle — which includes the waters of Indonesia, Malaysia and the Philippines — has around 75% of the world’s coral species. But these nurseries for marine life are under threat: globally, around 50% of living corals have been lost since the 1950s (T. D. Eddy et al. One Earth 4, 1278–1285; 2021). Moreover, climate change poses a large risk to their continued survival.One of Tara Pacific’s research groups has been focusing on genetic diversity — in particular, that of microbial communities (bacteria and archaea) living in Pacific Ocean corals. The scientists, led by marine microbiologist Pierre Galand at the Banyuls Oceanological Observatory in Banyuls-sur-Mer, France, collected more than 5,000 samples, and focused on analysing the 16S ribosomal DNA marker gene, which is used to identify and classify microorganisms. They found around half a million distinct DNA sequences known as amplicon sequence variants (ASVs), which can be used as a measure of the genetic diversity in a sample (Nature https://doi.org/kddz; 2023). From these data, the researchers estimated that the microbial diversity of coral reefs globally is probably around 2.8 million ASVs (P. E. Galand et al. Nature Commun. 14, 3039; 2023). For comparison, this is close to the lower end of one genetic-diversity estimate of all of Earth’s bacterial and archaeal communities — a proposed range of 2.72 million and 5.44 million ASVs (S. Louca et al. PLoS Biol. 17, e3000106; 2019). Galand and his colleagues’ work, which builds on smaller-scale studies of coral reefs (M. Chiarello et al. Proc. R. Soc. B 287, 20200642; 2020), confirms that Earth’s microbial genetic diversity is much higher and richer than previously thought.
Collection: Tara Pacific
The research ship has a stirring and unusual back story. Its original captain was Peter Blake, a much-decorated professional yachtsman from New Zealand. After retirement, Blake became an environmental envoy to the United Nations but was killed by pirates at the mouth of the Amazon River while on an expedition in 2001. Agnès Troublé, a French fashion designer known as Agnès B, and her son Etienne Bourgois acquired the boat, determined to continue Blake’s original vision. They established the Tara Ocean Foundation and invited scientists and research funders to join them on various missions.The logistics of converting a schooner into a floating laboratory and taking it on a 100,000-kilometre journey cannot be underestimated, especially considering the present complicated relations between Pacific nations. And then there’s the logistics of the research itself: organizing 3,000 dives; sending samples for PCR analysis en route; keeping the voyage on track.Researchers must continue to build on the work being reported and refine our understanding of the importance of diversity for safeguarding ecosystem stability and function. The project is a great example of visionary thinkers such as Troublé and Bourgois working closely with funders and scientists to help us to understand the breathtaking diversity of the world around us before it is too late. When it comes to preserving the natural systems we all depend on, more such collaborations are needed. More