Horizon scanning for South African biodiversity: A need for social engagement as well as science.

A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5-10 years. South African biodiversity experts submitted 63 issues of which ten were identified as priorities using the Delphi method. These priority issues were then plotted along axes of social agreement and scientific certainty, to ascertain whether issues might be "simple" (amenable to solutions from science alone), "complicated" (socially agreed upon but technically complicated), "complex" (scientifically challenging and significant levels of social disagreement) or "chaotic" (high social disagreement and highly scientifically challenging). Only three of the issues were likely to be resolved by improved science alone, while the remainder require engagement with social, economic and political factors. Fortunately, none of the issues were considered chaotic. Nevertheless, strategic communication, education and engagement with the populace and policy makers were considered vital for addressing emerging issues.

A framework to measure the wildness of managed large vertebrate populations.

As landscapes continue to fall under human influence through habitat loss and fragmentation, fencing is increasingly being used to mitigate anthropogenic threats and enhance the commercial value of wildlife. Subsequent intensification of management potentially erodes wildness by disembodying populations from landscape-level processes, thereby disconnecting species from natural selection. Tools are needed to measure the degree to which populations of large vertebrate species in formally protected and privately owned wildlife areas are self-sustaining and free to adapt. We devised a framework to measure such wildness based on 6 attributes relating to the evolutionary and ecological dynamics of vertebrates (space, disease and parasite resistance, exposure to predation, exposure to limitations and fluctuations of food and water supply, and reproduction). For each attribute, we set empirical, species-specific thresholds between 5 wildness states based on quantifiable management interventions. We analysed data from 205 private wildlife properties with management objectives spanning ecotourism to consumptive utilization to test the framework on 6 herbivore species representing a range of conservation statuses and commercial values. Wildness scores among species differed significantly, and the proportion of populations identified as wild ranged from 12% to 84%, which indicates the tool detected site-scale differences both among populations of different species and populations of the same species under different management regimes. By quantifying wildness, this framework provides practitioners with standardized measurement units that link biodiversity with the sustainable use of wildlife. Applications include informing species management plans at local scales; standardizing the inclusion of managed populations in red-list assessments; and providing a platform for certification and regulation of wildlife-based economies. Applying this framework may help embed wildness as a normative value in policy and mitigate the shifting baseline of what it means to truly conserve a species.

Un Marco de Trabajo para Medir el Estado Salvaje de Poblaciones de Vertebrados Mayores bajo Manejo Resumen Conforme los paisajes siguen cayendo bajo la influencia del humano por causa de la pérdida del hábitat y la fragmentación, cada vez se usa más el encercado para mitigar las amenazas antropogénicas o incrementar el valor comercial de la fauna. La intensificación subsecuente del manejo tiene el potencial para erosionar el estado salvaje al desincorporar a las poblaciones de los procesos a nivel de paisaje, desconectando así a las especies del proceso de selección natural. Por lo tanto, se necesitan herramientas para medir el grado al cual las poblaciones de especies de vertebrados mayores dentro de áreas de fauna protegidas y privadas son autosostenibles y libres de adaptarse. Diseñamos un marco de trabajo para medir dicho estado salvaje con base en seis atributos relacionados con las dinámicas evolutivas y ecológicas de los vertebrados (espacio, resistencia a las enfermedades y a los parásitos, exposición a la depredación, exposición a las limitaciones y fluctuaciones en las reservas de agua y alimentos, y reproducción). Para cada atributo, establecimos umbrales empíricos y específicos por especie entre cinco estados salvajes basados en las intervenciones de manejo cuantificables. Usamos datos de 205 propiedades privadas de fauna con objetivos de manejo que abarcan desde el ecoturismo hasta el uso para consumo para probar el marco de trabajo en seis especies de herbívoros con una gama de estados de conservación y valores comerciales. Los puntajes de estado salvaje entre las especies difirieron significativamente y la proporción de poblaciones identificadas como salvajes osciló del 12% al 84%, lo que indica que la herramienta detectó diferencias a escala de sitio entre las poblaciones de diferentes especies y las poblaciones de la misma especie bajo diferentes regímenes de manejo. Si cuantificamos el estado salvaje, este marco de trabajo les proporciona a los practicantes las unidades de medida estandarizadas que vinculan a la biodiversidad con el uso sostenible de la fauna. Las aplicaciones de este marco de trabajo incluyen informar a los planes de manejo de las especies a escalas locales; estandarizar la inclusión de las poblaciones manejadas en las evaluaciones de listas rojas; y proporcionar una plataforma para la certificación y regulación de las economías basadas en la fauna. La aplicación de este marco de trabajo puede ayudar a insertar a la fauna como un valor normativo dentro de la política y a mitigar la línea base cambiante de lo que significa conservar verdaderamente a una especie.

The ecological economics of kleptoparasitism: pay-offs from self-foraging versus kleptoparasitism.

Animals commonly steal food from other species, termed interspecific kleptoparasitism, but why animals engage in kleptoparasitism compared with alternate foraging tactics, and under what circumstances they do so, is not fully understood. Determining what specific benefits animals gain from kleptoparasitism could provide valuable insight into its evolution. Here, we investigate the benefits of kleptoparasitism for a population of individually recognizable and free-living fork-tailed drongos (Dicrurus adsimilis) in the southern Kalahari Desert. Drongos engaged in two foraging behaviours: self-foraging for small insects or following other species which they kleptoparasitized for larger terrestrial prey that they could not capture themselves. Kleptoparasitism consequently enabled drongos to exploit a new foraging niche. Kleptoparasitism benefitted drongos most in the morning and on colder days because at these times pay-offs from kleptoparasitism remained stable, while those from self-foraging declined. However, drongos engaged in kleptoparasitism less than expected given the overall high (but more variable) pay-offs from this behaviour, suggesting that kleptoparasitism is a risky foraging tactic and may incur additional foraging costs compared with self-foraging. This is the first study to comprehensively investigate the benefits of facultatively engaging in kleptoparasitism, demonstrating that animals may switch to kleptoparasitism to exploit a new foraging niche when pay-offs exceed those from alternate foraging behaviours.

Contrasting spatial patterns of taxonomic and functional richness offer insights into potential loss of ecosystem services.

Functional and trophic perspectives on patterns of species occurrences have the potential to offer new and interesting insights into a range of spatially explicit problems in ecology and conservation. We present the function-area relationship (FAR) and explore linkages between functional and taxonomic species richness for South African birds. We first used beak morphology to classify a subset of 151 South African bird species into 18 functional groups and calculated both the species-area relationship and the FAR at quarter-degree resolution for South Africa. The relationship between functional and taxonomic richness by cell was quadratic rather than linear, with considerable scatter around the curve. We next looked at the spatial relationships between taxonomic diversity and response diversity (i.e. diversity within functional groups) using an a priori categorization of nearly all South African birds into nine functional groups. The spatial distribution of response richness also showed considerable variation in relation to taxonomic richness. Our results demonstrate a novel approach to linking taxonomic, functional and trophic patterns in space and suggest a way in which conservation planning, which has traditionally had a taxonomic focus, could formally incorporate a more functional and food-web-based approach.

Interspecific audience effects on the alarm-calling behaviour of a kleptoparasitic bird.

Audience effects are increasingly recognized as an important aspect of intraspecific communication. Yet despite the common occurrence of interspecific interactions and considerable evidence that individuals respond to the calls of heterospecifics, empirical evidence for interspecific audience effects on signalling behaviour is lacking. Here we present evidence of an interspecific audience effect on the alarm-calling behaviour of the kleptoparasitic fork-tailed drongo (Dicrurus adsimilis). When foraging solitarily, drongos regularly alarm at aerial predators, but rarely alarm at terrestrial predators. In contrast, when drongos are following terrestrially foraging pied babblers (Turdoides bicolor) for kleptoparasitic opportunities, they consistently give alarm calls to both aerial and terrestrial predators. This change occurs despite no difference in the amount of time that drongos spend foraging terrestrially. Babblers respond to drongo alarm calls by fleeing to cover, providing drongos with opportunities to steal babbler food items by occasionally giving false alarm calls. This provides an example of an interspecific audience effect on alarm-calling behaviour that may be explained by the benefits received from audience response.