Collecting Data to Assess the Interactions Between Livestock and Wildlife

The need to identify interactions with the potential for pathogen transmission among the community of hosts at the wildlife–livestock interface has led to the development of multiple approaches in the field of epidemiology. Methodologies can be broadly classified into those that allow the quantification of interactions and those whose objective is to detect the existence of potential interactions at the interface. Regardless of their capacity to quantify or detect this potential, it is possible to study both direct (i.e., the simultaneous presence of two individuals at a certain point) and indirect (i.e., the sequential presence of two individuals at a certain point) interactions. Although each methodology has its specific pros and cons, when individuals are not marked, the main limitations are the difficulty involved in assessing the spatio-temporal resolution of events and, obviously, the role played by the individuals involved, the nature of the interaction, and the associated level of epidemiological risk. Furthermore, marking a limited number of individuals with different devices (e.g. GPS, proximity loggers) normally implies the possibility of low representativeness of the target population, especially when high variability exists in behaviour and connectedness of individual animals. The present chapter reviews the methodologies most commonly used to collect the data employed to assess interactions at the wildlife–livestock interface, namely, the direct observation of animals, epidemiological sampling, epidemiological questionnaires, camera traps, GPS technology, and proximity loggers. We also present the complementary nature of different methodologies by means of a specific case study of animal tuberculosis in the Iberian Peninsula. The methods selected have to adapt to the objectives of the study, logistic constraints, target host species and pathogens, and the routes of transmission at the wildlife/livestock interface.