Fur-rubbing with<i>Piper</i>leaves in the San Mart&amp;#237;n titi monkey,<i>Callicebus oenanthe</i>

We report observations on fur-rubbing with leaves from <i>Piper aduncum</i> by a San Martín titi monkey, <i>Callicebus oenanthe</i>. Fur-rubbing occurred during the transition from the dry to the rainy season in a titi monkey group living in a forest fragment in the Moyobamba region of Peru. Since <i>Piper</i> leaves include very potent compounds that may affect ectoparasites, we tentatively interpret the observed fur-rubbing as self-medication.