Methods for assessing movement path recursion with application to African buffalo in South Africa
2009
Bar-David, Shirli | Bar-David, Israel | Cross, Paul C. | Ryan, Sadie J. | Knechtel, Christiane U. | Getz, Wayne M.
Recent developments of automated methods for monitoring animal movement, e.g., global positioning systems (GPS) technology, yield high‐resolution spatiotemporal data. To gain insights into the processes creating movement patterns, we present two new techniques for extracting information from these data on repeated visits to a particular site or patch (“recursions”). Identification of such patches and quantification of recursion pathways, when combined with patch‐related ecological data, should contribute to our understanding of the habitat requirements of large herbivores, of factors governing their space‐use patterns, and their interactions with the ecosystem. We begin by presenting output from a simple spatial model that simulates movements of large‐herbivore groups based on minimal parameters: resource availability and rates of resource recovery after a local depletion. We then present the details of our new techniques of analyses (recursion analysis and circle analysis) and apply them to data generated by our model, as well as two sets of empirical data on movements of African buffalo (Syncerus caffer): the first collected in Klaserie Private Nature Reserve and the second in Kruger National Park, South Africa. Our recursion analyses of model outputs provide us with a basis for inferring aspects of the processes governing the production of buffalo recursion patterns, particularly the potential influence of resource recovery rate. Although the focus of our simulations was a comparison of movement patterns produced by different resource recovery rates, we conclude our paper with a comprehensive discussion of how recursion analyses can be used when appropriate ecological data are available to elucidate various factors influencing movement. Inter alia, these include the various limiting and preferred resources, parasites, and topographical and landscape factors.
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