Interspecific information transfer as a driver of community structure

What drives the abundance and distribution of animal species in space and time? This central question in ecology and conservation has so far been approached mainly by investigating the impact of predator-prey relationships and competition for limited resources such as food. However, it is becoming increasingly clear that animals may also have substantial effects on each other by acting as critical sources of information, for example when they communicate the presence of a predator or the location of food. The potential importance of information exchange between species is evident from the widespread occurrence of mixed-species groups in nature, in taxa ranging from spiders and fish to birds and mammals. Yet, currently almost nothing is known about how the advantage of living next to valuable informants affects patterns in social attraction between species.

Our study addresses this question from an integrated theoretical and empirical angle. We will build a general model to predict how information benefits shape the composition of mixed-species groups in nature. Our model will take into account the key costs and benefits from group life: (i) the information benefits from joining many eyes, ears and noses, (ii) the benefit of being close to others that may be eaten instead of you when predators attack, and (iii) the costs from increased competition over limited resources. To test our model in the real world, we focus on the mixed-species groups of herbivores dominating the African savannas in a field study. The many eyes, ears and noses in these herds are known to result in all-important information benefits when alarm signals are emitted. To determine how patterns in social attraction between species in this system depends on their value as informants, we use predator simulations and playback experiments to determine (i) the information contained in the alarm signals from each species in the community and (ii) to what extent this information is transferred between species. We will also obtain measures of the vulnerability of each herbivore species to the various predators in the community as well as costs from food competition when diets overlap. On this basis, we will be able to use social network analysis to test the role of communication (relative to other costs and benefits) as a driver of group formation between species. The savannah herbivore study will thus allow us to address fundamental questions in biology by (i) revealing which species within the community group together and why, and (ii) establishing the nature of coexistence between species: are multispecies groups mutually beneficial or do they rather form when one species parasitizes on the information produced by another?

The project will provide novel insights into the basic links between species in the natural environment by integrating communication benefits into classical food-web-based models of ecosystem structure. By establishing new fundamental principles that shape the social associations between species, the study will bring a deeper understanding of ecosystem dynamics that can be critical for identifying conservation priorities. Our conceptual framework will allow conservationists to assess when declines in key species are likely to have repercussions throughout the ecosystem by affecting the survival of others, and when these indirect effects are likely to become a conservation concern for endangered species.

We expect the work to benefit the following key end-users, nationally and internationally:
ACADEMIC COMMUNITY: A new conceptual framework that explicitly incorporates both social and trophic connections in models of community structure and resilience will advance the knowledge base for a broad range of academic disciplines, from Animal Behaviour and Evolutionary Biology to Ecology to Biomodeling. Specifically, the project will also provide high quality postdoctoral training for an accomplished Dphil-student by furthering his expertise in social network analysis, mathematical modelling, acoustic analysis and ecological fieldwork.
CONSERVATION MANAGERS: The development of a multi-layered network approach to account for interspecific interactions will provide a conservation tool to support the effectiveness of ecosystem management by allowing the consequences of species declines for the population viability of coexisting species to be assessed. In particular the impact of communication on population performance is relevant for managers of social wildlife species, notably mammals and birds, which include some of the most highly threatened taxa and therefore can be susceptible to even modest changes in ecological processes. Specifically, in collaboration with our project partner Kenya Wildlife Service we are organizing a conservation management workshop for stakeholders in conservation of the Mara ecosystem. This provides an urgently needed forum for addressing the extremely serious management issues that faces the region in these years. Drastic declines in wildlife populations have been documented due to intensifying illegal livestock grazing and other activities. The theme of the meeting will be the importance of interspecific interactions for ecosystem functioning and conservation, including wildlife-livestock conflicts. The main aim is to inform and influence the regional management practices of one of the world's most unique wildlife areas, a UNESCO World Heritage Site, at a critical time. Technologically, the project will specifically benefit managers of rangelands by groundtruthing satellite-derived vegetation indexes to assess their usefulness for quantifying sward characteristics in grassland systems.
ECOTOURISM INDUSTRY: The tourism sector is the 2nd largest source of foreign exchange revenue in Kenya, UK residents being the most frequent visitors. Wildlife is the main attraction and Masai Mara, the proposed study site, is by far the most visited park, receiving around 300,000 foreign visitors anually. By informing the management of savanna ecosystems in general and Masai Mara in particular, the project will support a wide range of stakeholders in the tourist industry. These include poor local households whose income relies on tourism directly or indirectly, companies in the tourist trade, both in Africa and worldwide, and the tourists themselves. The project will also enrich the tourist product by uncovering new facts about the behavioural ecology of African wildlife.
ANIMAL WELFARE: The project will benefit management of captive mammals by showing when anxiety is likely to transmit between species and welfare may be improved by separation (eg during veterinary interventions).
GENERAL PUBLIC: The large mammals of the African savanna hold a special fascination for the general public, and we will take advantage of this to improve the public understanding of environmental issues and science in general. The public will benefit from a deeper understanding of the interconnectedness of species in natural systems and increased societal awareness of the importance of sustainable use of natural resources.
SCHOOLS: Again, the study system provides an exceptional opportunity to engage school children in environmental science. We seek to stimulate pupils and students who are at critical points in their education with the aim of increasing their environmental awareness and potentially inspiring them to pursue a science career.