Claire A. Runge

Conserving mobile species

The distributions of many species are dynamic in space and time, and movements made by individuals range from regular and predictable migrations to erratic, resource-driven nomadism. Conserving such mobile species is challenging; the effectiveness of a conservation action taken at one site depends on the condition of other sites that may be geographically and politically distant (thousands of kilometers away or in another jurisdiction, for example). Recent work has shown that even simple and predictable linkages among sites caused by “to-and-fro” migration can make migratory species especially vulnerable to habitat loss, and substantially affect the results of conservation prioritizations. Species characterized by more erratic or nomadic movements are very difficult to protect through current conservation planning techniques, which typically view species distributions as static. However, collaborations between migration ecologists, conservation planners, and mathematical ecologists are paving the way for improvements in conservation planning for mobile species.

Protected areas and global conservation of migratory birds

Not enough protection for migrating birds Animals that migrate pass through a varying number of regions. Each of these regions contributes to a different component of their life cycles. Runge et al. looked at the degree of protection migratory birds receive, globally, across their breeding and wintering ranges. A remarkably low percentage of migratory birds receive adequate protection across their entire ranges. Given that over half the worlds migratory bird populations are declining, these results emphasize the urgency with which we must act to protect birds across their entire migratory cycle. Science, this issue p. 1255 Few migratory birds are protected across their entire range. Migratory species depend on a suite of interconnected sites. Threats to unprotected links in these chains of sites are driving rapid population declines of migrants around the world, yet the extent to which different parts of the annual cycle are protected remains unknown. We show that just 9% of 1451 migratory birds are adequately covered by protected areas across all stages of their annual cycle, in comparison with 45% of nonmigratory birds. This discrepancy is driven by protected area placement that does not cover the full annual cycle of migratory species, indicating that global efforts toward coordinated conservation planning for migrants are yet to bear fruit. Better-targeted investment and enhanced coordination among countries are needed to conserve migratory species throughout their migratory cycle.

Effective conservation requires clear objectives and prioritizing actions, not places or species.

In their recent article, Jenkins et al. (1) identify “priorities for future conservation investment” in the continental United States. To find these priority areas, the authors weighted species from six taxa by their range size and level of protection, summing the weighted maps to derive maps of priority scores. Such scoring systems defy contemporary planning approaches, and have repeatedly been shown to identify priorities that are biologically ineffective and economically inefficient (2).

Geographic range size and extinction risk assessment in nomadic species.

Geographic range size is often conceptualized as a fixed attribute of a species and treated as such for the purposes of quantification of extinction risk; species occupying smaller geographic ranges are assumed to have a higher risk of extinction, all else being equal. However many species are mobile, and their movements range from relatively predictable to-and-fro migrations to complex irregular movements shown by nomadic species. These movements can lead to substantial temporary expansion and contraction of geographic ranges, potentially to levels which may pose an extinction risk. By linking occurrence data with environmental conditions at the time of observations of nomadic species, we modeled the dynamic distributions of 43 arid-zone nomadic bird species across the Australian continent for each month over 11 years and calculated minimum range size and extent of fluctuation in geographic range size from these models. There was enormous variability in predicted spatial distribution over time; 10 species varied in estimated geographic range size by more than an order of magnitude, and 2 species varied by >2 orders of magnitude. During times of poor environmental conditions, several species not currently classified as globally threatened contracted their ranges to very small areas, despite their normally large geographic range size. This finding raises questions about the adequacy of conventional assessments of extinction risk based on static geographic range size (e.g., IUCN Red Listing). Climate change is predicted to affect the pattern of resource fluctuations across much of the southern hemisphere, where nomadism is the dominant form of animal movement, so it is critical we begin to understand the consequences of this for accurate threat assessment of nomadic species. Our approach provides a tool for discovering spatial dynamics in highly mobile species and can be used to unlock valuable information for improved extinction risk assessment and conservation planning. Tamaño de Extensión Geográfica y Evaluación de Riesgo de Extinción en Especies Nómadas Resumen El tamaño de extensión geográfica se conceptualiza frecuentemente como un atributo fijo de las especies y se trata como tal para los propósitos de cuantificación de riesgo de extinción; se asume que las especies que ocupan extensiones geográficas más pequeñas tienen un riesgo de extinción más alto, cuando todo lo demás es igual. Sin embargo, muchas especies son móviles y sus movimientos varían desde migraciones de ida y vuelta relativamente predecibles hasta movimientos irregulares complejos, como los que muestran las especies nómadas. Estos movimientos pueden llevar a expansiones sustanciales temporales y a una reducción de las extensiones geográficas, todo esto con el potencial de llegar a niveles que pueden presentar un riesgo de extinción. Al enlazar los datos de presencia con las condiciones ambientales al momento de la observación de las especies nómadas pudimos modelar las distribuciones dinámicas de 43 especies de aves de zonas áridas a lo largo de la isla de Australia durante cada mes a lo largo de once años y calculamos el tamaño de extensión mínima y el alcance de las fluctuaciones en el tamaño de extensión geográfica a partir de estos modelos. Hubo una enorme variabilidad en la distribución espacial pronosticada a lo largo del tiempo: diez especies variaron en el tamaño de extensión geográfica por más de una orden de magnitud y dos especies variaron por más de dos órdenes de magnitud. Durante situaciones de condiciones ambientales pobres, varias especies que actualmente no se encuentran clasificadas como amenazadas a nivel global redujeron sus extensiones a áreas muy pequeñas, esto a pesar de su gran tamaño de extensión geográfica normal. Este hallazgo genera preguntas sobre lo idóneo de las evaluaciones convencionales del riesgo de extinción con base en el tamaño estático de extensión geográfica (p. ej.: la Lista Roja de la UICN). Se pronostica que el cambio climático afectará los patrones de las fluctuaciones de recursos en casi todo el hemisferio sur, donde el nomadismo es la forma dominante de movimiento de animales, así que es crítico que comencemos a entender las consecuencias de esto para tener una evaluación certera del riesgo de extinción de especies nómadas. Nuestra estrategia proporciona una herramienta para descubrir las dinámicas espaciales de especies con movilidad alta y puede usarse para liberar información valiosa para una mejor evaluación de riesgo de extinción y planeación de la conservación.

Comparative terrestrial feed and land use of an aquaculture-dominant world

Significance Studies are revealing the potential benefits of shifting human diets away from meat and toward other protein sources, including seafood. The majority of seafood is now, and for the foreseeable future, farmed (i.e., aquaculture). As the fastest-growing food sector, fed aquaculture species increasingly rely on terrestrial-sourced feed crops, but the comparative impact of aquaculture versus livestock on associated feed and land use is unclear––especially if human diets shift. Based on global production data, feed use trends, and human consumption patterns, we simulate how feed-crop and land use may increase by midcentury, but demonstrate that millions of tonnes of crops and hectares could be spared for most, but not all, countries worldwide in an aquaculture-dominant future. Reducing food production pressures on the environment while feeding an ever-growing human population is one of the grand challenges facing humanity. The magnitude of environmental impacts from food production, largely around land use, has motivated evaluation of the environmental and health benefits of shifting diets, typically away from meat toward other sources, including seafood. However, total global catch of wild seafood has remained relatively unchanged for the last two decades, suggesting increased demand for seafood will mostly have to rely on aquaculture (i.e., aquatic farming). Increasingly, cultivated aquatic species depend on feed inputs from agricultural sources, raising concerns around further straining crops and land use for feed. However, the relative impact and potential of aquaculture remains unclear. Here we simulate how different forms of aquaculture contribute and compare with feed and land use of terrestrial meat production and how spatial patterns might change by midcentury if diets move toward more cultured seafood and less meat. Using country-level aquatic and terrestrial data, we show that aquaculture requires less feed crops and land, even if over one-third of protein production comes from aquaculture by 2050. However, feed and land-sparing benefits are spatially heterogeneous, driven by differing patterns of production, trade, and feed composition. Ultimately, our study highlights the future potential and uncertainties of considering aquaculture in the portfolio of sustainability solutions around one of the largest anthropogenic impacts on the planet.

Solving problems of conservation inadequacy for nomadic birds

Nomadic birds move around the landscape in complex, irregular patterns, making it difficult for conservation managers and planners to decide where and how to act to mitigate threatening processes. Because of this uncertainty, nomadic species are poorly represented in protected areas in Australia. We outline approaches to discover nomadic species distributions, their dynamics and their consequent vulnerability to extinction. Using citizen science initiatives like eBird Australia and the BirdLife Australia Atlas, combined with new ways of applying species distribution modelling that take into account temporal patterns of movement driven by weather and productivity, we demonstrate how to map and predict the key sites for conservation action for nomadic species. We explore recent advancements in decision-support tools to incorporate species movements into systematic conservation planning, and highlight challenges in traditional approaches for protected area designation for conserving nomads. Due to the spatio-temporal dynamism of nomadic species distributions, the projected costs of managing nomads across Australia using traditional, static, protected areas are prohibitive. Landholders, including graziers and indigenous landholders, will play a key role in safeguarding these species on pastoral lands into the future, and future conservation efforts should be focussed on these stakeholders, through a combination of community engagement, market-based incentives (such as biodiversity farming or payments for artificial water source and ephemeral wetland management), cross-boundary and cross-agency collaboration policies, and new legislative instruments. Accounting for the movements of nomadic species and incorporating new approaches to integrated land management will help design conservation solutions that are effective, cost-efficient, and robust to uncertainty in this rapidly changing world.

Quantifying the conservation gains from shared access to linear infrastructure

The proliferation of linear infrastructure such as roads and railways is a major global driver of cumulative biodiversity loss. One strategy for reducing habitat loss associated with development is to encourage linear infrastructure providers and users to share infrastructure networks. We quantified the reductions in biodiversity impact and capital costs under linear infrastructure sharing of a range of potential mine to port transportation links for 47 mine locations operated by 28 separate companies in the Upper Spencer Gulf Region of South Australia. We mapped transport links based on least-cost pathways for different levels of linear-infrastructure sharing and used expert-elicited impacts of linear infrastructure to estimate the consequences for biodiversity. Capital costs were calculated based on estimates of construction costs, compensation payments, and transaction costs. We evaluated proposed mine-port links by comparing biodiversity impacts and capital costs across 3 scenarios: an independent scenario, where no infrastructure is shared; a restricted-access scenario, where the largest mining companies share infrastructure but exclude smaller mining companies from sharing; and a shared scenario where all mining companies share linear infrastructure. Fully shared development of linear infrastructure reduced overall biodiversity impacts by 76% and reduced capital costs by 64% compared with the independent scenario. However, there was considerable variation among companies. Our restricted-access scenario showed only modest biodiversity benefits relative to the independent scenario, indicating that reductions are likely to be limited if the dominant mining companies restrict access to infrastructure, which often occurs without policies that promote sharing of infrastructure. Our research helps illuminate the circumstances under which infrastructure sharing can minimize the biodiversity impacts of development.