Influence of Food Resources on the Ranging Pattern of Northern Pig-tailed Macaques (Macaca leonina)

Food availability may influence primates' home range size and use. Understanding this relationship may facilitate the design of conservation strategies. We aimed to determine how fruit availability influences the ranging patterns of a group of northern pig-tailed macaques (Macaca leonina) living around the visitor center of Khao Yai National Park, Thailand. We predicted that macaques would increase their range during low fruit abundance periods to gather high-quality food and that they would go where there are more fruits or more fruits of particular species. We also predicted that human food, linked to human presence, would attract the macaques. We followed the macaques and recorded their diet and movements within their home range. We superimposed a grid on kernels defining the monthly home range surface to compare spatially macaques' travel and the availability of fruits measured on botanical transects. Our results showed that the macaques increased their monthly home range in March, probably to obtain newly available fruits. During high fruit abundance seasons, they spent more time near particular fruit species. In August and September, although fruits became rare again, macaques kept their home range large, perhaps to find enough fruits as supplies dwindled. Finally, from October to February, they decreased their monthly home range size while consuming human food, a high-quality item. In conclusion, the macaques used several ranging strategies according to fruit availability. However, we think that, without human food, macaques would tend to increase their range during low fruit abundance periods, as predicted.