Showing papers by "Simon N. Stuart published in 2005"

Using Red List Indices to measure progress towards the 2010 target and beyond.

Abstract: The World Conservation Union (IUCN) Red List is widely recognized as the most authoritative and objective system for classifying species by their risk of extinction. Red List Indices (RLIs) illustrate the relative rate at which a particular set of species change in overall threat status (i.e. projected relative extinction-risk), based on population and range size and trends as quantified by Red List categories. RLIs can be calculated for any representative set of species that has been fully assessed at least twice. They are based on the number of species in each Red List category, and the number changing categories between assessments as a result of genuine improvement or deterioration in status. RLIs show a fairly coarse level of resolution, but for fully assessed taxonomic groups they are highly representative, being based on information from a high proportion of species worldwide. The RLI for the world's birds shows that that their overall threat status has deteriorated steadily during the years 1988–2004 in all biogeographic realms and ecosystems. A preliminary RLI for amphibians for 1980–2004 shows similar rates of decline. RLIs are in development for other groups. In addition, a sampled index is being developed, based on a stratified sample of species from all major taxonomic groups, realms and ecosystems. This will provide extinction-risk trends that are more representative of all biodiversity.

Species Review of Amphibian Extinction Risks in Madagascar: Conclusions from the Global Amphibian Assessment

Abstract: We assessed the extinction risks of Malagasy amphibians by evaluating their distribution, occur- rence in protected areas, population trends, habitat quality, and prevalence in commercial trade. We estimated and mapped the distribution of each of the 220 described Malagasy species and applied, for the first time, the IUCN Red List categories and criteria to all species described at the time of the assessment. Nine species were categorized as critically endangered, 21 as endangered, and 25 as vulnerable. The most threatened species occur on the High Plateau and/or have been subjected to overcollection for the pet trade, but restricted ex- tent of occurrence and ongoing habitat destruction were identified as the most important factors influencing extinction threats. The two areas with the majority of threatened species were the northern Tsaratanana- Marojejy-Masoala highlands and the southeastern Anosy Mountains. The current system of protected areas includes 82% of the threatened amphibian species. Of the critically endangered species, 6 did not occur in any protected area. For conservation of these species we recommend the creation of a reserve for the species of the Mantella aurantiaca group, the inclusion of two Scaphiophryne species in the Convention on the International Trade in Endangered Species Appendix II, and the suspension of commercial collecting for Mantella cowani. Field surveys during the last 15 years reveal no pervasive extinction of Malagasy amphibians resulting from disease or other agents, as has been reported in some other areas of the world.

Habitat Suitability Models and the Shortfall in Conservation Planning for African Vertebrates

Abstract: : Ongoing loss of biodiversity requires identifying large-scale conservation priorities, but the detailed information on the distribution of species required for this purpose is often missing. We present a systematic reserve selection for 1223 African mammals and amphibians in which habitat suitability models are used as estimates of the area occupied by species. In the framework of the World Conservation Union (IUCN) Global Amphibian Assessment and IUCN Global Mammal Assessment, we collected the geographic range (extent of occurrence) and habitat preferences for each species. We used the latter to build species-specific habitat suitability models inside geographic ranges, and for 181 species we verified the models by comparing suitability levels to presence-absence data collected in the field. We then used the suitable areas as estimators of the area of occupancy and compared the results of systematic reserve selection based on geographic ranges to those based on estimated areas of occupancy. Our results showed that the reserve system would need a 30-100% expansion to achieve minimal conservation targets, concentrated in the tropics, where species richness reaches a maximum. Comparative analyses revealed that using geographic ranges, which overestimate the area occupied by species, underestimates the total amount of area that needs to be conserved. The area selected for conservation doubled when we used the estimated area of occupancy in place of the geographic ranges. This happened because the suitable areas potentially occupied by each species overlapped less than their geographic ranges. As a result, any given protected area contained fewer species than predicted by the analysis of ranges. Because species are more specialized than our estimates of distribution based on extent of occurrence suggest, we propose that this is a general effect in systematic conservation planning. Resumen: La perdida de biodiversidad en curso requiere la identificacion de prioridades de conservacion a gran escala, pero a menudo se carece de la informacion detallada sobre la distribucion de especies que se requiere para este proposito. Presentamos una seleccion sistematica de reservas para 1223 especies de mamiferos y anfibios africanos en la que se utilizan modelos de aptitud de habitat como estimaciones del area ocupada por las especies. En el marco de la Estimacion Global de Anfibios y la Estimacion Global de Mamiferos de la Union para la Conservacion Mundial (IUCN), recolectamos el rango geografico (extension de ocurrencia) y las preferencias de habitat de cada especie. Utilizamos a la preferencia de habitat para desarrollar modelos de aptitud de habitat especie especificos dentro de los rangos geograficos, y verificamos los modelos para 181 especies mediante la comparacion de los niveles de aptitud con datos de presencia-ausencia recolectados en el campo. Posteriormente utilizamos a las areas aptas como estimadores del area de ocurrencia y comparamos los resultados de una seleccion sistematica de reservas basada en rangos geograficos con los de una basada en areas de ocurrencia estimadas. Nuestros resultados mostraron que el sistema de reservas requeriria una expansion entre 20 y 100% para alcanzar metas de conservacion minimas, concentradas en los tropicos, donde la riqueza de especies alcanza su maximo. Los analisis comparativos revelaron que el uso de los rangos geograficos, que sobrestima al area ocupada por las especies, conduce a una subestimacion del area total que requiere ser conservada. El area seleccionada para conservacion se duplico cuando utilizamos el area de ocurrencia estimada en lugar de los rangos geograficos. Esto sucedio porque las areas potencialmente aptas ocupadas por cada especie tuvieron menor traslape que sus rangos geograficos. Como resultado, cualquier area protegida contenia menos especies que lo predicho por el analisis de rangos. Debido a que las especies estan mas especializadas que lo que sugieren nuestras estimaciones basadas en la extension de ocurrencia, proponemos que este es un efecto general en la planificacion sistematica de la conservacion.

Conservation theology for conservation biologists - A reply to David Orr

Abstract: As an international group of Christians from five continents who are also professionals in a variety of conservation-related disciplines, we write this response to David Orr’s recent essay “Armageddon versus Extinction” (Orr 2005). Although we agree there are some elements of truth in Orr’s essay, three aspects of his argument significantly disappoint us. First, we think he seriously misunderstands the nature of science and the nature of religion. Second, his understanding of the connection between “evangelicals” and “right-wing conservatives” seems to be based on an ill-informed understanding of what evangelicals believe, so we aim to clarify this. Third, we are deeply concerned that by generalizing to such an extent and then calling for confrontation, Orr will only fuel a conflict that will be damaging to conservation in the long term, when instead much could be gained by both parties from constructive engagement (as his essay hints at, but then shoots down). Although we are disappointed by these three aspects of Orr’s essay, and expand on these points below, we also want to make it clear that we are not rejecting his argument wholesale: it is unfortunately true that evangelical Christians have often been sluggish about caring for what they believe to be a world entrusted to human care by a loving God. We are greatly saddened by this reality, although as John Cobb (2005) pointed out in his thoughtful response to Orr’s essay, among the broader Christian community, evangelicals have often been ahead of other Christian traditions in “protecting declining species” and “respecting the integrity of creation.” In reality people associated with all religious and secular communities have contributed to the long history of environmental destruction, and most of us are living unsustainably. Our aim here, however, is not to exempt evangelicals from the charge of neglecting their responsibility to care for God’s world. We write this response therefore in an attempt to seek constructive engagement and to explain where and why we disagree with Orr’s approach. Space does not permit us to demonstrate fully that the popular view of evangelicals as obsessed with Armageddon, and hence opposed to conservation, is ill informed and overly simplistic. First, regarding Orr’s philosophy of science, he points out that conservation biologists “lack both a deep explanation of what ails us and a larger cosmology that resonates with the public” but wonders “whether the sciences can come together to tell a compelling, authentic, and lifeorienting story of our human sojourn.” We suggest that he is hoping for the sciences to deliver something that, by definition, they can never achieve. Science, on its own, cannot fulfill human aspirations and dreams. Science is about discovering the whats and the hows of the universe and does not address the deeper why questions relating purpose and meaning in life. Scientific method, valuable as it is (and most of us are scientists), is surely not the only way in which we gain knowledge. People in their daily lives employ other disciplines to gain understanding, including the arts, philosophy, and religion. By disparaging religion, and seemingly seeking to move science into its place, we think Orr is trying to make science do something that it can never do. Of course he is not alone in this, and the reduction of conservation to being technical science alone surely contributes hugely to its lack of appeal in certain communities. In a recent influential paper entitled “The Death of Environmentalism” (Shellenberger & Nordhaus 2004), the authors write, “What the environmental movement needs more than anything else right now is to take a collective step back to re-think everything. We will never be able to turn things around as long as we understand our failures as essentially tactical and make proposals that are essentially technical.” The far-sighted 1990 Union of Concerned Scientists’ Open Letter to the Religious Community, signed by 33 leading scientists worldwide, said of the global environmental situation: “Problems of such magnitude, and solutions demanding so broad a perspective, must be recognized from the outset as having a religious as well as a scientific dimension.” We agree strongly with Rick