Species’ declines are caused by a combination of factors that affect survival and/or breeding success. We studied the effects of a set of environmental and anthropogenic variables on the disappearance of Canarian Houbara Bustards Chlamydotis undulata fuertaventurae on Fuerteventura (Canary Islands), once the main stronghold of this endangered bird. Of 83 male display sites detected in 1997–1998, only 29 remained occupied in 2020–2021 (a 65% decrease in only 23 years). We compared habitat quality, density of conspecifics, other steppe birds and crows, presence of human infrastructure, and degree of environmental protection between these 29 extant sites and the 54 extinct sites using univariate analyses and generalised linear models (GLMs). The most influential variable in the abandonment of display sites was the Normalised Difference Vegetation Index (NDVI), an indicator of green vegetation productivity, which suggests a strong effect of habitat aridification due to climate change on the population’s extinction process. Powerline density was the second most important factor. This suggests that houbaras have survived where a greater abundance of food resources has enabled a higher breeding success, and where powerline fatalities have caused lower mortality over the years. Higher densities of houbaras, and other steppe birds and crows at extant display sites confirmed the better habitat quality in these areas. Extant display sites, located generally in protected areas, also had lower densities of human infrastructure (e.g. buildings, roads). We discuss the conservation implications of these results and provide management recommendations for this endangered subspecies.

This review essay contrasts two of the most notable recent contributions to literature on space and society: Daniel Deudney's Dark Skies (2020) and Brian Patrick Green's Space Ethics (2022). The Green volume is a course textbook, geared to giving students an overview of some of the key ethical issues concerning space and how the arguments on these matters are shaping up. Its aim is to provide an overview rather than a specific line of argument. Deudney's text, by contrast, is an example of a book proposing space skepticism. It argues that we should relinquish many of our current ambitions for space expansion on the grounds that they will increase the already significant degree of extinction-level risk that we face. The essay marks the distinction between these texts by contrasting normal- and special-domain approaches. Normal-domain approaches seek to extend familiar ethico-political issues into the discussion about space expansion without regarding space expansion as the road to utopia or extinction. Special-domain approaches hold to some such optimistic or pessimistic view. The essay goes on to highlight the way in which Green's text would benefit from more social critique, along the lines of Deudney. Ultimately, the normal-domain approach presupposed by Green and rejected by Deudney is upheld.

Many marine fish species are experiencing population declines, but their extinction risk profiles are largely understudied in comparison to their terrestrial vertebrate counterparts. Selective extinction of marine fish species may result in rapid alteration of the structure and function of ocean ecosystems. In this study, we compiled an ecological trait dataset for 8,185 species of marine ray-finned fishes (class Actinopterygii) from FishBase and used phylogenetic generalized linear models to examine which ecological traits are associated with increased extinction risk, based on the International Union for the Conservation of Nature Red List. We also assessed which threat types may be driving these species toward greater extinction risk and whether threatened species face a greater average number of threat types than non-threatened species. We found that larger body size and/or fishes with life histories involving movement between marine, brackish, and freshwater environments are associated with elevated extinction risk. Commercial harvesting threatens the greatest number of species, followed by pollution, development, and then climate change. We also found that threatened species, on average, face a significantly greater number of threat types than non-threatened species. These results can be used by resource managers to help address the heightened extinction risk patterns we found.

Processes of extinction, especially selectivity, can be studied using the distribution of species in morphospace. Random extinction reduces the number of species but has little effect on the range of morphologies or ecological roles in a fauna or flora. In contrast, selective extinction culls species based on their functional relationship to the altered environment and, therefore, to their position within a morphospace. Analysis of the distribution of extinctions within morphospaces can thus help understand whether the drivers of the extinction are linked to functional traits. Current approaches include measuring changes in disparity, mean morphology, or evenness between pre- and post-extinction morphologies. Not all measurements are straightforward, however, because morphospaces may be non-metric or non-linear in ways that can mislead interpretation. Dimension-reduction techniques like principal component analysis – commonly used with highly multivariate geometric morphometric data sets – have properties that can make the center of morphospace falsely appear to be densely populated, can make selective extinctions appear randomly distributed, or can make a group of non-specialized morphologies appear to be extreme outliers. Applying fully multivariate metrics and statistical tests will prevent most misinterpretations, as will making explicit functional connections between morphology and the underlying extinction processes.

Between 20 and 24 marine extinctions, ranging from algal to mammal species, have occurred over the past 500 years. These relatively low numbers question whether the sixth mass extinction that is underway on land is also occurring in the ocean. There is, however, increasing evidence of worldwide losses of marine populations that may foretell a wave of oncoming marine extinctions. A review of current methods being used to determine the loss of biodiversity from the world’s oceans reveals the need to develop and apply new assessment methodologies that incorporate standardized metrics that allow comparisons to be made among different regions and taxonomic groups, and between current extinctions and past mass extinction events. Such efforts will contribute to a better understanding of extinction risk facing marine flora and fauna, as well as the ways in which it can be mitigated.

Government conservation measures will always depend on public support. While more has been learnt about which species the public values and which conservation measures are socially acceptable, less is known about the criteria that the public thinks government should consider when making conservation investment decisions. This study uses a stated preference best–worst scaling method to gauge the views of a sample of the Australian public on what they think government should consider when allocating funding to threatened species conservation. We found that the three most important factors were the risk that a species might become extinct, the likelihood that a conservation intervention might be effective and the risk of unintended consequences for other species that could potentially arise if the measure was implemented. Costs of conservation measures and the degree to which the society accepts these costs were considered much less important. The latter aspect was consistent with the high level of trust that respondents placed in the judgement of experts and scientists concerning threatened species conservation. We conclude that the Australian Government has a societal mandate to spend more money on threatened species conservation, provided that there is little risk and that it is backed up by science.

The assessment of the conservation status of a species is the first step in developing a conservation strategy. IUCN Red Lists assessments are an important starting point for conservation actions and the most commonly applied method for assessing the extinction risk of a species. In this study, the global conservation status of the rock rose Helianthemum caput-felis Boiss. (Cistaceae), a perennial Mediterranean plant, was evaluated using the Red List criteria. The distribution of the species was determined by monitoring historical localities and all other suitable sites along the western Mediterranean coasts for 6 years. For each confirmed locality, the ecological and population parameters and the main threats were recorded; these data were used in a quantitative analysis of the species' extinction risk. Our findings indicate there have been several recent extinctions, and there is a continuing decline in the species' area of occurrence, habitat quality and number of reproductive plants. The main threats are related to human activities. Extinction models indicate a probability of quasi-extinction risk of c. 30% in five generations or c. 45% in three generations, with the species likely to become extinct in seven currently known localities within the next 10 years. Application of the Red List criteria indicates H. caput-felis should be categorized as Endangered. This study confirms that legal protection and passive conservation measures are insufficient to guarantee the persistence of a plant species. Active conservation and management actions are needed to protect this and other threatened species of the Mediterranean Basin.

This study examines conservation effects of wildlife trade using demand and supply data from caged-bird markets in Sumatra, Indonesia. When consumers have a strong preference for species rarity, trade could result in wildlife overexploitation and species extinction. Results from a choice experiment show that buyers of caged birds indeed value species rarity. However, not all rare species are equally preferred. Species that are frequently traded lose their rarity value, even if rare in the wild. Analysis of time-series data collected from traders over a period of 20 months between 2013 and 2015 reveals an inelastic supply function for rare species, with market arrivals being insensitive to price changes. This may be due to a declining stock of rare species in the wild. Bird trade together with habitat loss can lead to extinction of a number of rare species in Indonesia. Several policy approaches on regulating caged-bird markets are discussed.

Quantitative analysis of macroecological patterns for late Pleistocene assemblages can be useful for disentangling the causes of late Quaternary extinctions (LQE). However, previous analyses have usually assumed linear relationships between macroecological traits, such as body size and range size/range shift, that may have led to erroneous interpretations. Here, we analyzed mammalian datasets to show how macroecological patterns support climate change as an important driver of the LQE, which is contrary to previous analyses that did not account for more complex relationships among traits. We employed quantile regression methods that allow a detailed and fine-tuned quantitative analysis of complex macroecological patterns revealed as polygonal relationships (i.e., constraint envelopes). We showed that these triangular-shaped envelopes that describe the macroecological relationship between body size and geographical range shift reflect nonrandom extinction processes under which the large-bodied species are more prone to extinction during events of severe habitat loss, such as glacial/interglacial transitions. Hence, we provide both a theoretical background and methodological framework to better understand how climate change induces body size-biased species sorting and shapes complex macroecological patterns.

Although trees have high economic, cultural and ecological value, increasing numbers of species are potentially at risk of extinction because of forest loss and degradation as a result of human activities, including overharvesting, fire and grazing. Emerging threats include climate change and its interaction with the spread of pests and diseases. The impact of such threats on the conservation status of trees is poorly understood. Here we highlight the need to conduct a comprehensive conservation assessment of the world's tree species, building on previous assessments undertaken for the IUCN Red List. We suggest that recent developments in plant systematics, online databases, remote sensing data and associated analytical tools offer an unprecedented opportunity to conduct such an assessment. We provide an overview of how a Global Tree Assessment could be achieved in practice, through participative, open-access approaches to data sharing and evaluation.

The Tropical Andes are characterized by a high level of endemism and plant species richness but are under pressure from human activities. We present the first regional conservation assessment of upper montane tree species in this region. We identified 3,750 tree species as occurring in this region, of which 917 were excluded because of a lack of data on their distribution. We identified a subset of 129 taxa that were restricted to higher elevations (> 1,500 m) but occurred in more than one country, thus excluding local endemics evaluated in previous national assessments. Distribution maps were created for each of these selected species, and extinction risk was assessed according to the IUCN Red List categories and criteria (version 3.1), drawing on expert knowledge elicited from a regional network of specialists. We assessed one species, Polylepis microphylla, as Critically Endangered, 47 species as Endangered and 28 as Vulnerable. Overall, 60% of the species evaluated were categorized as threatened, or 73% if national endemics are included. It is recommended that extinction risk assessments for tree species be used to inform the development of conservation strategies in the region, to avoid further loss of this important element of biodiversity.

The conservation of species listed in the Bern Convention and European Directive 1992/43/EEC (so-called policy species) is mandatory for European Union (EU) countries. We assessed the conservation status of Italian policy species, based on the IUCN categories and criteria, to evaluate the effectiveness of existing protection measures at the national level. Among the 203 vascular plants, bryophytes and lichens evaluated, 41.9% are categorized as threatened, and one is already extinct, indicating that the protection measures for policy species are inadequate. Our results for the Italian policy species are consistent with those of an assessment at the EU level. Conservation priorities should be established at both the national and regional scales. An effective conservation strategy is needed, and in situ and ex situ actions focused on threatened species should be promoted.

In Brazil most of the effort for the conservation of plant species has comprised evaluation of taxa for the Lista Oficial das Espécies Ameaçadas de Extinção da Flora Brasileira (Official Threatened Flora Species List), and little has been done to conserve individual species. This is a result of the listing process being interpreted as the final goal rather than as a means to achieve conservation effectiveness. In addition, a variety of systems for the classification of extinction risk have been applied, resulting in an inaccurate view of the conservation status of the flora of the country. Here we review the national listing process to highlight the strengths and weaknesses of the Official Threatened Flora Species List. We used all available information to compile a list of taxa officially recorded as threatened in Brazil. The list was revised using the Flora do Brasil database. The resulting list has 4,967 taxa in 1,235 genera and 232 families. Despite controversies about advances in the Red Listing process, several improvements have been made at the institutional level, such as: (1) improving conservation databases, (2) developing information systems, and (3) increasing the number of taxonomists working in conservation biology. However, there is still no classification system for extinction risk that facilitates standardization of the listing process at the national level. In addition, regulatory processes related to the conservation of threatened plant species are not up-to-date with the conceptual and methodological advances made by the scientific community. We conclude that adjustments are needed to ensure the effectiveness of the conservation of plant species in Brazil.

The poor survival rate of immature northern bald ibises Geronticus eremita during their first years spent outside the natal site is driving the last known wild colony of the migratory eastern population to extinction. To inform emergency conservation action for this Critically Endangered species we investigated the distribution range and behaviour of immature birds in passage and wintering areas, and the threats to which they are subject. We integrated recent satellite telemetry data with visual observations spanning 130 years. We assessed threats across the range, using satellite tracking and field surveys. Our results show that during the years before they return to the natal site in Syria, immature northern bald ibises reside away from the recently identified adult wintering site in the central Ethiopian highlands. They occur mainly across the northernmost 70–80% of the adult migratory range. Historical records suggest that immature birds spend more time along the western Arabian Peninsula now than in the past. This range shift exposes them for longer periods to threats, such as hunting and electrocution on power lines, which are absent from the wintering site used by adult birds. We suggest that other threatened and declining bird species sharing the same flyway probably face the same threats during migration.

Rose's mountain toad Capensibufo rosei survives in a few isolated montane populations in the south-western Cape of South Africa. It comprises several cryptic species but it is uncertain whether the lineage on the Cape Peninsula is distinct. We tested the hypothesis that toads from the Peninsula form a single genetic lineage but that different breeding sites are divergent at a population level as a result of limited dispersal abilities. Directed surveys were carried out to locate breeding sites and samples obtained were analysed in a phylogenetic and population genetic framework, using two mitochondrial markers. We found toads breeding at only one of five known historical breeding sites, although one new breeding site was also recorded. No toads were observed at 15 other non-breeding localities where they were historically observed. Toads from the two active breeding sites formed a single lineage that was sufficiently distinct to be given species status. However, these were discrete at a population level, with no shared haplotypes, suggesting no gene flow between sites. One site was particularly low in genetic diversity, implying increased vulnerability to stochastic events and elevated risk of extinction. These results, coupled with the failure to locate historically known sites on the Cape Peninsula, make this newly recognized Peninsula endemic a conservation priority. Efforts should focus on the protection and expansion of the two known surviving populations and the patches of habitat upon which they rely.

The Global Plan of Action for Animal Genetic Resources calls for action to conserve the wild species that are related to livestock. The global conservation status of wild species is monitored through the IUCN Red List. This shows that at present 21 percent of the world's 5 488 mammal species and 12 percent of its 9 990 bird species are threatened with extinction. In contrast, a greater proportion of wild relatives of the major mammal livestock species are at risk of extinction: 44 percent of sheep and goats, 50 percent of pigs and 83 percent of cattle. More wild relatives of the chicken are also at risk (25 percent) than bird species overall. These figures indicate the need to pay much more attention to the relationship between the conservation of biological diversity and human well-being. Therefore, there is an urgent need to coordinate responses to the loss of biodiversity and the reduction in variation that may prove vital for animal genetic resources in the future. Intergovernmental meetings being held this autumn offer the prospect of beginning this process.

The Uluguru Mountains in eastern Tanzania contain at least 16 endemic vertebrate and 135 endemic plant taxa, with hundreds of more taxa shared only with forests in eastern Tanzania and Kenya. This degree of endemism is exceptional in tropical Africa, and the Uluguru Mountains are one of the 10 most important tropical forest sites for conservation on the continent. Surveys carried out during 1999–2001 updated information on the status of forests and biodiversity across the Uluguru Mountains. Forest area has declined from c. 300 km2 in 1955 to 230 km2 in 2001. Forest loss has been greatest over altitudes of 600–1,600 m, and concentrated in submontane forest. During the recent surveys most of the endemic and near-endemic vertebrate species known from the Uluguru Mountains were re-recorded, but three endemic snake species and two near-endemic bird species were not found. These species were previously known from the elevations where deforestation has been greatest. More than 50 plant species are also known only from the altitude range that has been heavily deforested. The primary cause of forest loss has been clearance for new farmland. The forest that does remain is largely confined to Catchment Forest Reserves managed for water by the Tanzanian Government. Without these reserves the loss of forest, and hence the loss of biodiversity, in the Uluguru Mountains would most likely have been much greater.

A spring (1999) census was conducted of great bustards Otis tarda in north-western Morocco, where a poorly known population of this species occurs. Sixty-four birds were seen in four distinct areas. Adult males were seen displaying at three of these areas, indicating that they are probably traditional lek sites. No adult males were observed in the fourth area and its status as a lek site is uncertain. Two further sites were visited but no birds were seen. Two lst-year males were seen with their mothers, demonstrating successful breeding in 1998. We argue that the small number of birds, a population sex ratio of 1:3.3 in favour of females, evidence for a range contraction, and probable isolation from other great bustard populations mean that this population is now extremely endangered and will decline to extinction unless conservation measures are implemented immediately.