IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Zehnder, A. | |
| Home range analyses and kill site detection of lions and leopards in the Kalahari, Botswana | |
| 2015 Full Book | |
By analyzing home ranges and kill sites, this study addressed two major aspects of the ecology of leopards and lions in the Khutse and Central Kalahari Game Reserve, Botswana. Regarding home ranges, four methods were selected to investigate the effect of their parameterization: MCP, KDE, t-LCH and BRB. First, the effect of the parameters was analyzed for each method. Then, systematic trends of the methods were analyzed. The most appropriate versions of each method were used to analyze the home ranges of the individual leopards and lions in an ecological context. An emphasis thereby was to examine the temporal variability of the results in terms of their area and shape. It was found that the _k_-rule of t-LCH performed markedly better than the _a_-rule. The inclusion of time scaling factors yielded more interconnected isopleths whose shape indicated moving pathways. For BRB, the ecological model used to set the smoothing parameter turned out to be critical and to cause problems in conjunction with heterogeneous sampling intervals. On average, MCP produced home ranges whose areas and shapes differed significantly from those of the other methods. The areas of KDE, t-LCH and BRB were similar whereas their shapes allowed for a better differentiation. The observed individuals have home ranges that are among the largest worldwide and mostly within the protected area. Particularly the home ranges of the lions varied markedly over time, emphasizing the need to consider different temporal aggregations. Despite their largely overlapping home ranges, the leopards rarely encountered and thus indicate a strong active avoidance behavior. Regarding kill sites, the performance of a clustering approach was analyzed by using different variables to indicate the probability of a cluster to be an actual kill site through weights. The sets of variables that yielded the lowest errors were used to determine the spatial distribution of kill sites in terms of their proportion inside the core area, home range and game reserves. The combination of the cluster duration and ratio of distances moved before and after a cluster proved to yield the lowest errors, while the time of day had hardly any impact. The incorporation of additional variables consistently led to higher success rates regarding the detection of kill sites. Irrespectively of the criterion used to set the weight threshold, the ratios of kill sites within the core area and home range remained stable. Almost all detected kill sites were within the home range. Two lions that were shot because of livestock predation proved to have small proportions of kill sites outside the game reserves. However, these ratios seemed to be too low to justify their killing. It is thus likely that spatiotemporal clustering approaches cannot detect such clusters reliably. |
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