Validation of a Noninvasive Hair Trapping Method for Extractive-Foraging Primates

Hair is a useful source of biological information. For example, the bulb can be a source of high-quality genetic material, whereas the shaft can be useful for measuring heavy metals and some hormones, such as cortisol. The stable isotope composition of hair is another valuable source of biological information. Consequently, noninvasive methods of hair sampling have become important research tools. Several hair-trapping methods have been developed for use on mammals, but these are rarely deployed on primates in part because their travel patterns can be difficult to predict and because many species are averse to novel objects in their environments. Yet if a species has a natural propensity to envision, manipulate, and withdraw extractable food resources, then a baited receptacle lined with double-sided tape may prove successful as a hair trap. Recently, researchers demonstrated the success of such a contraption with tufted capuchins, a Neotropical monkey species with a high degree of somatosensory intelligence and a proclivity for extractive foraging. Here, we replicate this method in a population of tool-using long-tailed macaques (Macaca fascicularis). Our trials validate the effectiveness of the method, suggesting that it is suitable for long-tailed macaques and other extractive-foraging primates.