Land-use changes can impact infectious disease transmission by increasing spatial overlap between people and wildlife disease reservoirs. In Malaysian Borneo, increases in human infections by the zoonotic malaria Plasmodium knowlesi are hypothesised to be due to increasing contact between people and macaques due to deforestation. To explore how macaque responses to environmental change impact disease risks, we analysed movement of a GPS-collared long-tailed macaque in a knowlesi-endemic area in Sabah, Malaysia, during a deforestation event. Land-cover maps were derived from satellite-based and aerial remote sensing data and models of macaque occurrence were developed to evaluate how macaque habitat use was influenced by land-use change. During deforestation, changes were observed in macaque troop home range size, movement speeds and use of different habitat types. Results of models were consistent with the hypothesis that macaque ranging behaviour is disturbed by deforestation events but begins to equilibrate after seeking and occupying a new habitat, potentially impacting human disease risks. Further research is required to explore how these changes in macaque movement affect knowlesi epidemiology on a wider spatial scale. Electronic supplementary materialThe online version of this article (10.1007/s10393-019-01403-9) contains supplementary material, which is available to authorized users.

In non-human primate systems, the Ecological Model of Female Social Relationships (EMFSR) views variation in female social structure as adaptations to variation in recent past and/or current ecological conditions. Group size may be a major additional demographic factor affecting social structure through its effects on resource competition. In particular, in Resident Nepotistic Despotic (RND) societies, when resources are uniformly clumped, larger groups are expected to face higher levels of within-group contest competition (WGC) than smaller groups and to respond by showing more highly despotic social relationships than smaller groups. On the other hand, smaller groups are expected to face higher levels of between-group contest competition (BGC) and hence, show greater levels of intragroup tolerance (or lower despotism). While formal models do not explicitly predict this kind of variation within species, many researchers have investigated such intraspecific variation. Thus, we tested these predictions across three groups of free-ranging rhesus macaques (Macaca mulatta) of varying sizes on Cayo Santiago, Puerto Rico, where we were able to control for variation in resource-patch contestability and predation risk. Subjects were adult females. For each group, we collected data on (1) exposure and (2) behavioural reactions to WGC and BGC at two independent sets of clumped resources (feeding corrals and drinking stations) and (3) agonistic and affiliative social behaviour, using focal animal, all occurrences, and ad-libitum sampling methods. As predicted, our largest group showed the greatest levels of exposure and behavioural responses to WGC contexts. Likewise, our smallest group showed greatest levels of exposure and responses to BGC contexts. However, aspects of social structure did not vary across groups in directions predicted by the EMFSR. These findings are broadly consistent with several previous comparative tests of the model on other primate taxa that found strong links between group size, ecological factors and contest competitive regimes, but little or no evidence of links with social structure. Our study adds strength to these conclusions given our unique ability to control for several variables on Cayo Santiago. We suggest that our findings may be generalizable to several wild rhesus populations in North India, given that they have lived in similarly dense populations and have been frequently provisioned by humans for thousands of years.

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Density estimates are a common tool for assessing potential changes in primate populations over time and for evaluating important habitat characteristics such as preferred food sources. There are several different methods for estimating the density and population of wild primates, though the accuracy of these methods across different habitats and species is difficult to assess. We calculated the density of the population of Müller's gibbon (Hylobates muelleri) in the pristine and regenerating forest in Sungai Wain Protection Forest in East Kalimantan, Indonesia from May to July 2012. We collected data on the location of bonded pairs and compared the results of two different density estimate methods: triangulation and point transect sampling using Distance software. The triangulation method yielded population estimates of 486.9 ± SD 132.6 individuals in the pristine forest and 274.3 ± SD 179.0 in the regenerating forest. Distance analysis produced population estimates of 580.5 ± CV 20.6 and 388.4 ± CV 23.4 individuals for the pristine and regenerating forest, respectively. The difference in the density estimates between methods was not significant. We hypothesize that point transect sampling overestimated group density based on the unusually high estimate, Int J Primatol 5 Orangutan Tropical Peatland Project, Palangka Raya, Central Kalimantan, Indonesia but further investigation into the accuracy of point transect analysis using Distance with respect to gibbons is needed. We conclude that triangulation remains an important tool for hylobatid surveys because of its efficacy in locating gibbon groups using acoustic detection.