ORIGINAL ARTICLE Valentina Carrai ® Silvana M. Borgognini-Tarli Michael A. Huffman ® Massimo Bardi Increase in tannin consumption by sifaka (Propithecus verreauxi verreauxi ) females during the birth season: a case for self-medication in prosimians? Received: 1 May 2002 / Accepted: 10 September 2002 / Published online: 20 November 2002 Ó Japan Monkey Centre and Springer-Verlag 2002 Abstract In this study we report preliminary data on the consumption of tannin-rich plants by sifakas (Propithe- cus verreauxi verreauxi) living in the Kirindy forest, western Madagascar. Sifakas spent most of their time feeding on only a few plant species. The tannin intake during the period between the pregnancy and birth season was significantly higher in pregnant females or females with lactating infants than in non-reproductive females and males. These periparturient females secured a larger proportion of condensed tannins by short feeding bouts on plants not included in the group’s limited preferred food species. The measured increase in tannin intake is puzzling in light of the fact that tannins are commonly known for their protein-binding proper- ties. Since protein demands are highest in pregnant and lactating females, possible medicinal benefits of tannin ingestion are considered. Tannin consumption is asso- ciated with an increase in body weight and stimulation of milk secretion. Veterinarians administer tannins as an astringent, anti-hemorrhagic and anti-abortive. Their high potential as an alternative anthelminthic has also recently been recognized. Thus, when viewed as self- medicating behavior, controlled increase in tannin intake could have multiple prophylactic advantages for females during the periparturient period. The high selectivity in their plant choice, and the presence of unusual feeding habits by a particular group of indi- viduals (females with infants) limited in time (birth season), suggests that an increase in tannin ingestion may be a self-medicating behavior with multiple directly adaptive benefits to female reproduction. Keywords Self-medication ® Condensed tannins ® Sifaka females ® Reproductive benefits Introduction The study of self-medication, or zoopharmacognosy, is a relatively new field in the discipline of animal behavior (see Huffman 2001; Engel 2002). Research on primate self-medication was first inspired by Janzen (1978) and gained momentum with the observation of chimpanzees in western Tanzania (Wrangham and Nishida 1983; Huffman and Seifu 1989) and baboons in Ethiopia (Phi- lips-Conroy 1986) consuming plants of known medicinal value. Further detailed studies pointed to the control of internal parasite infection and/or relief from the related discomfort as a principle function of such behavior in the African great apes (e.g., Huffman et al. 1993, 1996; Wrangham 1995; Huffman and Caton 2001). Geophagy and charcoal ingestion, two variations of the same form of self-medication, are widely reported among apes and monkeys (Krishnamani and Mahaney 2000). Based on the excellent absorptive capacity of charcoal and clay, self-medication is proposed as a means of relieving gastric distress brought on by the ingestion of too much toxic plant material, intestinal parasite infection or a restricted diet etc. (e.g., Cooney and Struhsaker 1997; Wakibara et al. 2001). It has been proposed, for black lemurs and capuchins, that rubbing volatile insect or plant matter into the fur, controls infestation by ectoparasites (Baker 1996; Birkinshaw 1999; Valderrama et al. 2000). All of these behaviors are considered to enhance, in one way or another, the user’s immediate wellbeing and thus increasing the user’s chances of survival. Little is known to date about the possibility of self- medication directly altering reproductive fitness. It has been suggested that secondary compounds in the pri- mate diet can enhance or inhibit reproductive outcome. For example, although tentative, intriguing evidence has been presented to suggest that feeding on seasonally available plants with known phytoestrogens may medi- Primates (2003) 44: 61–66 DOI 10.1007/s10329-002-0008-6 V. Carrai ® S.M. Borgognini-Tarli ® M. Bardi Department of Ethology, Ecology, Evolution, University of Pisa, Pisa, Italy M.A. Huffman (&) Section of Ecology, Primate Research Center, Kyoto University, Kanrin 2–41, Inuyama 484–8506, Japan E-mail: huffman@pri.kyoto-u.ac.jp Tel.: +81-568-630538 Fax: +81-568-630358