The difference conservation makes to extinction risk of the world's ungulates

Previous studies show that conservation actions have prevented extinctions, recovered populations, and reduced declining trends in global biodiversity. However, all studies to date have substantially underestimated the difference conservation action makes because they failed to account fully for what would have happened in the absence thereof. We undertook a scenario-based thought experiment to better quantify the effect conservation actions have had on the extinction risk of the world's 235 recognized ungulate species. We did so by comparing species’ observed conservation status in 2008 with their estimated status under counterfactual scenarios in which conservation efforts ceased in 1996. We estimated that without conservation at least 148 species would have deteriorated by one International Union for Conservation of Nature (IUCN) Red List category, including 6 species that now would be listed as extinct or extinct in the wild. The overall decline in the conservation status of ungulates would have been nearly 8 times worse than observed. This trend would have been greater still if not for conservation on private lands. While some species have benefited from highly targeted interventions, such as reintroduction, most benefited collaterally from conservation such as habitat protection. We found that the difference conservation action makes to the conservation status of the world's ungulate species is likely to be higher than previously estimated. Increased, and sustained, investment could help achieve further improvements. La Diferencia que Hace la Conservación en el Riesgo de Extinción de los Ungulados del Mundo Los estudios previos muestran que las acciones de conservación han prevenido extinciones, recuperado poblaciones y reducido las tendencias de declinación en la biodiversidad mundial. Sin embargo, todos los estudios a la fecha han subestimado sustancialmente la diferencia que hace la acción de conservación ya que fallaron en representar de lleno lo que podría pasar en ausencia de esta. Emprendimos un experimento reflexivo con base en escenarios para cuantificar de mejor manera el efecto que las acciones de conservación han tenido sobre el riesgo de extinción de las 235 especies reconocidas de ungulados en el mundo. Hicimos esto al comparar el estado de conservación de la especie observado en 2008 con su estado estimado bajo escenarios contrafáctico en los cuales los esfuerzos de conservación cesaron en 1996. Estimamos que sin la conservación, al menos 148 especies habrían empeorado su categoría en la Lista Roja de la Unión para la Conservación de la Naturaleza (UICN), incluidas seis especies que ahora aparecerían como extintas o extintas en estado silvestre. La declinación general en el estado de conservación de los ungulados habría sido casi ocho veces peor de lo que se observó. Esta tendencia habría sido mayor si no fuera por la conservación en tierras privadas. Mientras algunas especies se han beneficiado de intervenciones altamente enfocadas, como la reintroducción, la mayoría se benefició colateralmente de la conservación, como la protección de hábitat. Encontramos que la diferencia que hace la acción de conservación en el estado de conservación de las especies de ungulados probablemente sea mayor de lo que se estimó previamente. Una inversión aumentada, y sostenida, podría ayudar a obtener más mejorías. Current evidence indicates a growing mismatch between increasing pressures to biodiversity and conservation responses (Tittensor et al. 2014). Success, however, is not uncommon in the field of biodiversity conservation (Sodhi et al. 2011; Balmford 2012). Extinctions of some species have been prevented (Butchart et al. 2006; Brooke et al. 2008), population trajectories have improved (Donald et al. 2007; Deinet et al. 2013; Chapron et al. 2014), and the risk of extinction of wild species has decreased (Hoffmann et al. 2010). There have been increased calls for evidence-based conservation to actively demonstrate this effectiveness to funders, policy formers, and the public (Sutherland et al. 2004). However, while other policy fields of global importance undertake extensive evaluations of success (Ferraro Kapos et al. 2009). Therefore, opportunities to efficiently allocate limited resources, encourage the application of effective policies, and inspire people to become involved in biodiversity conservation may be missed (Ferraro Geldmann et al. 2013]; with and without law enforcement guards Tranquilli et al. 2012) or through correlations between the magnitude of the intervention and of biodiversity condition (e.g., protected area coverage vs. changes in extinction risk Butchart et al. 2012). However, conservation takes places through a diversity of actions (e.g., protected areas and legislation), with various degrees of synergy among them, and measuring the overall impact of these actions cannot be done by simply summing the impacts of individual actions (Rodrigues 2006). One way to explore what would have happened without conservation actions is to construct a counterfactual scenario – a hypothetical scenario that estimates what would have happened if conservation actions had not actually taken place (Ferraro Ferraro 2009). Hoffmann et al. (2010) previously documented 68 species of mammals, birds, and amphibians known to have improved in conservation status in recent decades due to conservation efforts. They found that, if such conservation successes had not occurred, the overall deterioration in conservation status in these 3 taxa would have been one-fifth worse again than that observed. However, these authors cautioned that their study underestimated true conservation impact because it only examined species that improved in conservation status. In practice, in the absence of conservation, some species that remained unchanged in status may have actually deteriorated or species that deteriorated over the time period considered may have deteriorated further (or even gone extinct). These, too, are conservation successes, but they are less straightforward to identify. In a different study, Butchart et al. (2006) identified at least 16 critically endangered bird species that likely would have gone extinct between 1994 and 2004 without conservation action. These authors also underestimated conservation impact because they focused solely on the avoidance of species extinctions. However, conservation is not only about preventing highly threatened species from becoming extinct, but also about keeping common species from becoming threatened (Gaston 2010). We explored further the difference conservation makes by focusing on ungulates as a case study. We investigated how conservation efforts affected their extinction risk by comparing their observed International Union for Conservation of Nature (IUCN) Red List categories between 1996 and 2008 with the conservation status that we estimated they would have had under a hypothetical scenario where all conservation actions ceased at the start of the period. We then used the IUCN Red List Index (RLI), an established method (e.g., Tittensor et al. 2014) that tracks trends over time in overall extinction risk of species, to compare the observed RLI with that resulting from our hypothetical scenario. Individual species are likely to differ in terms of how they actually benefit from conservation. For example, some species may benefit from directly targeted conservation actions (such as reintroduction efforts) that mitigate species-specific threats (e.g., Dobson see Supporting We used these categories to an observed RLI for ungulates as a measure of their conservation between 1996 and To our counterfactual we estimated what species’ red-list category would have been in 2008 if all conservation actions had ceased in 1996 the 2008 counterfactual red-list This may but to an of the difference global conservation is it is to a where such are by based on a of what however, whereas scenarios are (e.g., et al. 2000), our scenario was least one recent study has an of conservation impact based on a scenario and et al. 2014). scenario of no conservation action that all for conservation to in 1996. is to to formal protected areas but for ungulates in the private also a in conservation We 2008 counterfactual red-list categories under scenario where private is not considered as to conservation, and scenario where private for conservation purposes were as if they were formal protected to scenario as our counterfactual because private is not of conservation were not to population to quantify of extinction in the absence of conservation action. Instead, the used by Butchart et al. we used information to on population and of of their and and conservation interventions to as as possible how the extinction risk of species would have had conservation action ceased in 1996 Supporting We used information in the for ungulates published on the IUCN Red List IUCN action (e.g., et al. status (e.g., et al. and (e.g., however, using the and categories to the of our by an and counterfactual RLI under We did not all species’ be better with than without conservation. some species could have benefited from the absence of conservation (e.g., by increasing in due to the decline of our is that species would have no change without conservation we had to We conservation action as action that could be according to the of conservation actions et al. 2008). We did not we these often have conservation This many to in or not a intervention be included in the 2008 counterfactual red-list actions that have species may or may not have a true biodiversity conservation or For example, we did not actions (e.g., as conservation they have been as in the of conservation and not for public some or have a impact in terms of biodiversity conservation (e.g., from in but has been in but we did not these as conservation actions because these generally are not included in conservation and the effect of of conservation is the The result of such (i.e., actions and difficult to quantify such as is a more as individual species may be directly affected by targeted threats or collaterally affected by more general so species are likely to benefit directly from targeted conservation actions and collaterally from less specific We 6 of species based on the to which they were the of targeted conservation action to the to which they were directly targeted by threats in We then ungulate species to of these 6 or species are affected by targeted but they also benefit from targeted conservation These are species may also species of that have been affected (e.g., because of their or because their is in with and are highly but they have also been to targeted conservation actions (such as reintroduction and and species-specific species are affected collaterally by threats and benefit collaterally from conservation These species are not directly However, they may be generally affected by threats (i.e., the in keeping with the of et al. is at the or not at the and are not to conservation efforts rather benefit from more general such as habitat or in place for other species are affected collaterally by but they benefit from targeted conservation actions their has been species are affected by targeted but they benefit only collaterally from conservation with species, these species are directly targeted by threats or (i.e., the is at the species and in or to the However, species, they are not to conservation efforts. they benefit from more general such as habitat or in place for other species. species are or affected by directly or They may benefit directly from targeted conservation benefit or not benefit at These species may in or a of or to and of species not conservation action. They may be affected by affected collaterally by or be or affected by This category all species by conservation and those for which conservation interventions are (e.g., because they in a of even they may be affected by The observed trend in the RLI for ungulates that their overall status deteriorated from 1996 to by This the observed for all mammals, where the RLI by from 1996 to 2008 (Hoffmann et al. 2010). In scenario conservation we identified ungulate species that we estimated would have deteriorated in conservation status by one or more IUCN Red List categories over the period with that actually these species, nearly would have deteriorated from least to threatened 3 that or threatened that The counterfactual RLI under this scenario would have by at least and between and for the most and assessments scenario conservation action including conservation on private we estimated that species would have deteriorated in conservation status by one or more The counterfactual RLI would have by between 1996 and 2008 (or and between and for the most and The trends in RLI described in of the scenarios be more directly if a more or of the of ungulate species by one IUCN Red List category between 1996 and in the observed 148 in scenario and in scenario than of all ungulate species or were to targeted threats these only a benefited from conservation action but many more benefited from conservation. In at least species and were affected by threats habitat due to or including 3 that conservation and that benefited collaterally from conservation species were not substantially affected by threats The to the difference between the observed RLI and the counterfactual RLI as under scenario was by species of for of the impact species had a more (i.e., less 2008 observed red-list category in 2008 than they would have had in the absence of conservation The of the was by species which 16 had a more 2008 observed red-list category than the followed by of the and species had no difference between their 2008 observed and counterfactual red-list categories and no to the of the counterfactual RLI. of all species in had a better conservation status in their observed categories than in the We observed trends in the world's ungulate species between 1996 and 2008 would have been different if all conservation interventions ceased at the start of this period. suggested that the overall decline in the conservation status of ungulates would have been nearly 8 times worse than to an of ungulate species by one red-list category year from 1996 to 2008 with the observed of than species that actually did a deterioration over this of all species would have deteriorated in status by one category between 1996 and 2008 and would have deteriorated by or more categories The of ungulates as threatened would have increased from the of non-data species observed in 2008 to to an species from least or threatened to a threatened The estimated of decline increased further when the of private to conservation was our counterfactual species deteriorated by one red-list category the biodiversity of private 2014). For one species, the common we estimated that conservation actions prevented a deterioration from least to critically the population of the for some of population and we estimated that of (e.g., by the of et al. and increased pressures (e.g., of the et al. would have to in this for this species, without habitat likely would have been sufficient to as critically endangered in 2008, based on a decline over 3 We estimated that conservation actions have prevented the and extinction of at least species, and greater The species has been from in the period we an to the of conservation efforts in the to et al. 2014). pressures due to no conservation would we have the possible of the listed as critically endangered in 1996 and We estimated further that 3 species would have been listed as extinct in the wild were it not for conservation action The did extinct in the the last were in in the but it has been to extensive and reintroduction efforts the and was recently classified as The of conservation actions in 1996 would have in the reintroduction efforts would not have been from extinct in the wild in 1996 to observed category of critically endangered in 2008 if and had The species, likely would have been from highly due to and habitat but it would have in some private The of species in our data was not that ungulates are a for and to would be that the overall impact of conservation on such species would not be given that, in the threats are not and species only benefit in a from conservation (e.g., through habitat or efforts However, our that conservation a for example, to to are to of for or with at While have been or no species-specific interventions targeted at these protected areas have to because they areas for at least some of enforcement (e.g., et al. among a group as as species targeted are relatively in However, they account for a of the difference between the observed and counterfactual RLI. these highly species, conservation action is targeted and often to mitigate between the higher categories (e.g., critically endangered to extinct in the In the absence of for example, would not have from extinct in the wild to and greater would be and species are even in and account for to of the difference between the species, conservation action could result in in red-list categories as species are from threats that could be For such species, and critically we than that would have gone extinct without however, is that without conservation interventions, the status of would be and species no to the difference between the observed and counterfactual species included many species that have a higher of for or and a of For these species, the impact of conservation was because by if are no threats is no even if be or conservation. species did not benefit from conservation action. These included species in the of where protected areas are and are no targeted For of ungulate species, we estimated that their 2008 counterfactual red-list categories would have been the same as their 2008 observed red-list categories conservation did not their risk of extinction in the wild. However, red-list categories are and so our method cannot population changes to change between For example, under of the IUCN Red List and a population decline and over 3 an endangered a conservation action the of a species’ population decline from to over 3 the species classified as endangered in would have no difference to the counterfactual RLI. This to our an of conservation Hoffmann et al. (2010) that the RLI would have by an for mammals in the absence of conservation that conservation efforts are a their to ungulates the RLI would have by an from that observed Supporting based on a method that takes account not only the of conservation actions on species’ but also for their on preventing show that the RLI would have by an in the absence of conservation These cannot be directly to mammals in we found that different species to the impact of conservation actions and ungulates are by species that are to be of species conservation were the most common in our data it is likely that most are by species one habitat is the among mammals (Schipper et al. 2008), and most species are collaterally by protected areas (Rodrigues et al. 2004). the other species in the most orders (e.g., are a targeted by conservation actions and so most are likely to be In species targeted are likely to be rare among these even if they be more in a with higher species (e.g., and we that for mammals in general trends in the counterfactual RLI under the same scenario that we would not be as as those we estimated for ungulates because the have more species that benefit from targeted conservation However, because we show that species that benefit collaterally from conservation actions also substantially to the difference between the observed and counterfactual we that the application of our to all mammals would that conservation a difference to observed trends in extinction this by our to a group of species. The with our is that a counterfactual for species a analysis of the of the threats they are to and conservation actions they benefit An way of our method to a group would be to a (i.e., of species has been done for the of a RLI et al. and the counterfactual for this from which of conservation impact could be The to our study is the of our estimates of extinction risk under a no conservation scenario. This may but the was not to a but rather a hypothetical one that would to measure the overall impact of conservation. We used the information to to the likely of species in this scenario. This involved a of the hypothetical of our study, we to on the of in our estimates of the 2008 counterfactual red-list categories in not to our of the decline in the RLI for scenario substantially to the than to the one and is more likely to be an of conservation impact than an demonstrate that conservation actions have to common species or at least prevented deteriorations in extinction risk from to higher categories of while to highly threatened species from We also that while conservation has to species from extinct, through species-specific interventions, the of species have from conservation efforts we an improved of conservation it remains an We our study is an to help one of conservation most difficult our further evidence that conservation action is a difference to trends in biodiversity. a in investment et al. in such efforts is to global efforts and achieve global biodiversity We are to the for data and the of the counterfactual red-list categories possible in our our the and We to the many of in the and and of the IUCN all of their and time to the of data on the IUCN Red Butchart many and that improved the as did 3 This is to the of the IUCN most of for the of threatened species. have been but not The is not for the or of information by the than be to the for the