Ayesha I. T. Tulloch

Predicting species distributions for conservation decisions.

Species distribution models (SDMs) are increasingly proposed to support conservation decision making. However, evidence of SDMs supporting solutions for on-ground conservation problems is still scarce in the scientific literature. Here, we show that successful examples exist but are still largely hidden in the grey literature, and thus less accessible for analysis and learning. Furthermore, the decision framework within which SDMs are used is rarely made explicit. Using case studies from biological invasions, identification of critical habitats, reserve selection and translocation of endangered species, we propose that SDMs may be tailored to suit a range of decision-making contexts when used within a structured and transparent decision-making process. To construct appropriate SDMs to more effectively guide conservation actions, modellers need to better understand the decision process, and decision makers need to provide feedback to modellers regarding the actual use of SDMs to support conservation decisions. This could be facilitated by individuals or institutions playing the role of ‘translators’ between modellers and decision makers. We encourage species distribution modellers to get involved in real decision-making processes that will benefit from their technical input; this strategy has the potential to better bridge theory and practice, and contribute to improve both scientific knowledge and conservation outcomes.

Why do we map threats? Linking threat mapping with actions to make better conservation decisions

Spatial representations of threatening processes – “threat maps” – can identify where biodiversity is at risk, and are often used to identify priority locations for conservation. In doing so, decision makers are prone to making errors, either by assuming that the level of threat dictates spatial priorities for action or by relying primarily on the location of mapped threats to choose possible actions. We show that threat mapping can be a useful tool when incorporated within a transparent and repeatable structured decision-making (SDM) process. SDM ensures transparent and defendable conservation decisions by linking objectives to biodiversity outcomes, and by considering constraints, consequences of actions, and uncertainty. If used to make conservation decisions, threat maps are best developed with an understanding of how species respond to actions that mitigate threats. This approach will ensure that conservation actions are prioritized where they are most cost-effective or have the greatest impact, rather than where threat levels are highest.

A behavioural ecology approach to understand volunteer surveying for citizen science datasets

Abstract Among other outcomes, volunteer surveys are useful for evaluating conservation success and determining priorities for management actions. However, biases that can originate from untargeted and weakly structured surveys can undermine the utility of the data gathered. Identifying and rectifying biases and problems with such data require an understanding of the behaviour of volunteers. We explored the characteristics of volunteer behaviour using bird surveys conducted in south-western Australia, and evaluated how volunteer behaviour affects the quantity and quality of data when volunteers are unconstrained in their selection of survey sites. We related the home-range and site-fidelity of 172 volunteers to the availability of habitat and bird species. Habitat selection by volunteers was assessed using avian species-accumulation curves, which identified 12 habitats for which avian species inventories were <95% complete. Volunteer biases resulted in skewed representation of birds in the resulting dataset. We recommend the minimum sampling effort required for reliable species-richness estimates in each habitat, and suggest ways to achieve spatial representativeness by using different behavioural types. Volunteers with high site-fidelity (often locals) produce high species detection rates, and are useful for long-term monitoring or surveying in less-favoured habitats close to urban areas. Roaming volunteers (often tourists) with large home-ranges are useful for threatened species surveying and can fill gaps far from urban areas, but might require incentives to visit unfavoured habitats, given their high habitat and bird selectivity. By studying volunteer behaviour, we can set realistic goals to achieve a comprehensive dataset useful for research, management and conservation planning.

A new framework for selecting environmental surrogates

Surrogate concepts are used in all sub-disciplines of environmental science. However, controversy remains regarding the extent to which surrogates are useful for resolving environmental problems. Here, we argue that conflicts about the utility of surrogates (and the related concepts of indicators and proxies) often reflect context-specific differences in trade-offs between measurement accuracy and practical constraints. By examining different approaches for selecting and applying surrogates, we identify five trade-offs that correspond to key points of contention in the application of surrogates. We then present an 8-step Adaptive Surrogacy Framework that incorporates cross-disciplinary perspectives from a wide spectrum of the environmental sciences, aiming to unify surrogate concepts across disciplines and applications. Our synthesis of the science of surrogates is intended as a first step towards fully leveraging knowledge accumulated across disciplines, thus consolidating lessons learned so that they may be accessible to all those operating in different fields, yet facing similar hurdles.

Understanding the importance of small patches of habitat for conservation

Conservation activities in fragmented landscapes have largely focused on keeping remaining large patches intact, often disregarding the increasingly important role of smaller patches in the conservation of remaining vegetation. As habitat loss proceeds in fragmented landscapes, there is an increasing need to measure the relative contribution of all patches (large and small) to overall ecosystem persistence, in a way that helps deliver effective conservation strategies aimed at preventing the death of ecosystems by a thousand cuts. Using Australian vegetation communities as a case study, we calculated the historical change in the contribution of patches below different sized thresholds to overall extent. We introduced a new patch assessment metric based on the Gini coefficient that indicates how unequal the distribution of patch sizes is relative to historical distributions. At least 22% of major vegetation communities in Australia have >50% of their remaining extent in patches <1000 ha. Loss does not always match fragmentation status: though some vegetation communities are exposed to the double jeopardy of high loss and high fragmentation, others are far more affected by fragmentation than loss of extent. For some communities, actions focused on protecting large patches are critical but for many others, protecting and managing small patches is crucial for community persistence. Synthesis and applications. Arbitrary patch size thresholds for permitting native vegetation clearing are dangerous for ecosystems whose distribution is now restricted to small patches. We recommend that clearing thresholds be scaled to reflect the fact that some ecosystems are more dominated by small patches than others. With a renewed focus on formally assessing the threat status of ecosystems as well as species, ecosystem accounts such as those demonstrated in this study are the first step to reliably assessing vulnerability. Measures of ecosystem vulnerability that only consider the extent of vegetation loss and not the size of remaining patches are likely to be ineffective for impact assessment, conservation planning and preventing ecosystem loss. Arbitrary patch size thresholds for permitting native vegetation clearing are dangerous for ecosystems whose distribution is now restricted to small patches. We recommend that clearing thresholds be scaled to reflect the fact that some ecosystems are more dominated by small patches than others. With a renewed focus on formally assessing the threat status of ecosystems as well as species, ecosystem accounts such as those demonstrated in this study are the first step to reliably assessing vulnerability. Measures of ecosystem vulnerability that only consider the extent of vegetation loss and not the size of remaining patches are likely to be ineffective for impact assessment, conservation planning and preventing ecosystem loss. Journal of Applied Ecology

Floristic and structural components of habitat use by the eastern pygmy-possum (Cercartetus nanus) in burnt and unburnt habitats

The eastern pygmy-possum (Cercartetus nanus) occurs broadly but patchily in south-eastern Australia. It is a small, difficult-to-trap marsupial with poorly known resource and habitat preferences. This study investigated the structural and floristic habitat resources used and selected by C. nanus in Royal National Park (which was heavily burnt by bushfire in 1994) and Heathcote National Park (most of which had remained unburnt for over two decades at the time of study), in central-coastal New South Wales. Three different sampling methods were used – pitfall traps, Elliott traps and hair tubes – with pitfall trapping being by far the most effective method for detecting C. nanus. Live-trapping in different habitats revealed higher numbers of C. nanus in unburnt and burnt woodland, burnt heathland and burnt coastal complex than in unburnt coastal complex and burnt and unburnt rainforest. To identify the components of habitat contributing to this pattern, we first scored floristic and structural features of vegetation around trap stations and then quantified habitat components further by using spool- and radio-tracking. We found little evidence that C. nanus responded to any structural components of habitat, although arboreal activity was greater, not surprisingly, in wooded than in burnt heathland habitats. C. nanus was associated most strongly with the abundance of certain plants in the Proteaceae and Myrtaceae. In particular, the species prefers Banksia spp. (probably for food) and Eucalyptus and Xanthorrhoea spp. (probably for shelter).

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.

Accounting for Complementarity to Maximize Monitoring Power for Species Management

To choose among conservation actions that may benefit many species, managers need to monitor the consequences of those actions. Decisions about which species to monitor from a suite of different species being managed are hindered by natural variability in populations and uncertainty in several factors: the ability of the monitoring to detect a change, the likelihood of the management action being successful for a species, and how representative species are of one another. However, the literature provides little guidance about how to account for these uncertainties when deciding which species to monitor to determine whether the management actions are delivering outcomes. We devised an approach that applies decision science and selects the best complementary suite of species to monitor to meet specific conservation objectives. We created an index for indicator selection that accounts for the likelihood of successfully detecting a real trend due to a management action and whether that signal provides information about other species. We illustrated the benefit of our approach by analyzing a monitoring program for invasive predator management aimed at recovering 14 native Australian mammals of conservation concern. Our method selected the species that provided more monitoring power at lower cost relative to the current strategy and traditional approaches that consider only a subset of the important considerations. Our benefit function accounted for natural variability in species growth rates, uncertainty in the responses of species to the prescribed action, and how well species represent others. Monitoring programs that ignore uncertainty, likelihood of detecting change, and complementarity between species will be more costly and less efficient and may waste funding that could otherwise be used for management.

Incorporating Socioeconomic and Political Drivers of International Collaboration into Marine Conservation Planning

International collaboration can be crucial in determining the outcomes of conservation actions. Here, we propose a framework for incorporating demographic, socioeconomic, and political data into conservation prioritization in complex regions shared by multiple countries. As a case study, we quantitatively apply this approach to one of the worlds most complex and threatened biodiversity hotspots: the Mediterranean Basin. Our analysis of 22 countries surrounding the Mediterranean Sea showed that the strongest economic, trade, tourism, and political ties are clearly among the three northwestern countries of Italy, France, and Spain. Although economic activity between countries is often seen as a threat, it may also serve as an indicator of the potential of collaboration in conservation. Using data for threatened marine vertebrate species, we show how areas prioritized for conservation shift spatially when economic factors are used as a surrogate to favor areas where collaborative potential in conservation is more likely.

The exceptional value of intact forest ecosystems

As the terrestrial human footprint continues to expand, the amount of native forest that is free from significant damaging human activities is in precipitous decline. There is emerging evidence that the remaining intact forest supports an exceptional confluence of globally significant environmental values relative to degraded forests, including imperilled biodiversity, carbon sequestration and storage, water provision, indigenous culture and the maintenance of human health. Here we argue that maintaining and, where possible, restoring the integrity of dwindling intact forests is an urgent priority for current global efforts to halt the ongoing biodiversity crisis, slow rapid climate change and achieve sustainability goals. Retaining the integrity of intact forest ecosystems should be a central component of proactive global and national environmental strategies, alongside current efforts aimed at halting deforestation and promoting reforestation.Forests that are free of significant human-induced degradation should be accorded urgent conservation priority, it is argued, owing to evidence that they hold particular value for biodiversity, carbon sequestration and storage, water provision, and the maintenance of indigenous cultures and human health.