Plant Species Fed on by Lemur catta in Gallery Forests of the Southern Domain of Madagascar

Abstract

In this paper, we provide an overview of the feeding trends of Lemur catta, the ringtailed lemur, including a checklist of all plant species and plant items known to be ingested by this prosimian species in three different forests of southwestern and southern Madagascar. Ringtailed lemurs have been mainly studied in gallery forests including riverine forest, closed canopy forest, and drier habitats with opened forests and scrub as distance perpendicular to the river increases. There is little published information on food species eaten con-sistently in other areas throughout the distribution range of this species such as in the dry spiny forest (Didiereaceae and arborescent Euphorbiaceae forests) or in montane areas up to 2000 m [see however, the study of Rakotoarisoa (1999) in the Andringitra massif; and Goodman et al. (this volume)]. The checklist provided here thus emphasizes plant species from the gallery forests and asso-ciated drier areas, with few observations made in spiny forests and mixed dry forest and bush. The three field areas considered here are respectively the southwestern sites of Antserananomby and the Beza Mahafaly Special Reserve, and in the south the Berenty Private Reserve. In these areas, groups of ringtailed lemurs have been studied intensively, in some cases over several years, and/or are under current studies. It should be noted that dietary differences described below between ring-tailed lemurs of Berenty and those of Beza Mahafaly appear to a great extent linked to the availability of many more introduced plant species in the first site and still some human-derived food and water. Detailed information on geograph-ical locations and plant species composition of the study sites can be found in Jolly (1966), Sussman (1974), O'Connor (1988), and Sussman and Rakotozafy (1994). Food plants collected and dried as herbarium samples have been identi-fied by botanists from the Missouri Botanical Garden and the Muséum National d'Histoire Naturelle, Paris (France), in collaboration with the Parc Zoologique et Botanique de Tsimbazaza, Antananarivo. 56 B. Simmen et al. 5.2. Food Plants, Food Items, and Seasonal Variations Ringtailed lemurs are considered mainly frugivorous/folivorous primates that can shift their diet toward either leaves or fruits as one main food category in differ-ent seasons. They have been observed feeding on ripe and unripe fruits, young and mature leaves, leaf stems, flowers, unripe seeds, and dead wood; additionally, they ingest parts of termite galleries as well as small pieces of earth and they prey on invertebrates and on vertebrates on rare occasions (Jolly, 1966; Sussman, 1974, 1976; Budnitz and Dainis, 1975; Sauther, 1992, 1998; Yamashita, 2002; Simmen et al., 2003; Soma, this volume; S. Ichino, pers. comm.). Lemur catta apparently shows adaptations to feeding on poor-quality leaves or leaves that are rich in secondary metabolites (see Simmen et al., this volume; Ganzhorn, 1986). With a somewhat enlarged haustrated caecum (Campbell et al., 2000), ringtailed lemurs harbor an intestinal symbiotic flora that is assumed to facilitate leaf fer-mentation and that, to some extent, may help detoxify foods. Geophagy is quite frequently observed and may be a behavioral response to coping with toxic foods, leading to the neutralization of leaf tannins through adsorption by clay (Johns and Duquette, 1991). In Antserananomby, where groups have been studied during the late dry sea-son, ringtailed lemurs feed on at least 23 species. In Beza Mahafaly and Berenty where lemur feeding behavior and diet has been repeatedly investigated relative to both feeding strategy and social organization as well as reproductive state, at least 61 and 109 plant species, respectively, with a wide variety of plant food items, are included in the diet (Table 5.1). At Beza Mahafaly, 40 plant species are used for leaves, 28 species for fruits and 16 species for flowers. At Berenty, 82 plant species are used by lemurs for leaves, 40 for fruits and 38 for flowers. In terms of the number of plant species or food items used, the diet of Lemur catta thus appears relatively diverse. However, only a few species within this food repertoire actually play a major role in any season, once dietary proportions are accounted for. Such a feeding pattern would correspond, overall, with an unse-lective, opportunistic feeding behavior: the diet reflects to a great extent the com-position and structure of the gallery forest, a relatively low-diversity environment in which less than 15 tree species account for most of the total basal area (Berenty: O'Connor, 1988; Simmen and Tarnaud, unpublished results; see also Sussman and Rakotozafy, 1994, for Beza Mahafaly). This also reflects the avail-ability of introduced plant species at Berenty, especially for groups foraging near the tourist area. Tamarindus indica (vernacular name: kily) has long been recognized as a key-stone resource (sensu Terborgh, 1986) in gallery forests inhabited by ringtailed lemurs (Jolly, 1966; Sussman and Rakotozafy, 1994; Sauther, 1998; Blumenfeld-Jones, this volume; Mertl-Millhollen et al., this volume). At Beza Mahafaly, Tamarindus indica is an important food resource as it is the only species that is used throughout the year (Figure 5.1). At Berenty, kily ripe pods are used inten-sively during the late dry–early wet season, when females give birth and lactate, and may still be consistently ingested during the wet season in favorable years.