Lemur rubriventer I. Geoffroy, 1850
Order PRIMATES
Family LEMURIDAE
The Red-bellied Lemur is found, apparently sparsely distributed, throughout the eastern rain forests of Madagascar. Population numbers are unknown but this species may be the rarest of those in the genus Lemur. It is probably being reduced in number by the destruction of the forests throughout its range. Little is known about the ecology and social organization of Lemur rubriventer, but it is currently being studied near Ranomafana in the south-east. It lives in small groups, is mostly diurnal, though some nocturnal activity has been reported, and it feeds on fruit, flowers and leaves. It has been reported in four protected areas. There are around 17 individuals in captivity, about one third of these have been born there. Listed in Appendix I of CITES, Class A of the African Convention and protected by Malagasy law.
Found throughout the eastern rain forest (Petter and Petter, 1971) from Tsaratanana Massif in the north to Ivohibé, at the southern end of the Andringitra Massif (Tattersall, 1982). It is apparently confined to forests at medium and high altitudes (Petter et al, 1977, Tattersall, 1982). Petter and Petter-Rousseaux (1979) show the range of this species extending as far as Mananara River, somewhat further south than shown in Tattersall (1982).
Said to be the rarest of the true lemur species (Jolly et al, 1984), but there are no estimates of numbers. L. rubriventer is reported to live at very low densities (Jolly et al, 1984) and Tattersall (1982) considers that they are only sparsely distributed throughout their range. The one estimate of population density, in the region around Ranomafana, was of 30 individuals per sq. km (Overdorff, 1988). Population numbers are considered to be declining due to habitat destruction (Richard and Sussman, 1975,1987).
There have been three studies of this species in the rain forest near Ranomafana, in southeastern Madagascar. One was for six months from January to June 1986 (Dague and Petter, 1988), another and was in June and July 1986 (Overdorff, 1988) and the third was from July 1986 to January 1987 (Meier, 1987). Four of seven groups censused in the south-eastern forests (at Ranomafana and Kianjavato) consisted of an adult pair of lemurs and one of these also contained a juvenile female; of the remainder; one group contained only two males and one contained three males, while the seventh was composed of an adult female and three adult sized males (Overdorff, 1988). In the longer study, groups composed of an adult pair with a juvenile were seen most commonly (32.8% n=64 observations), adult pairs were seen ten times, single males or females were observed on 11 occasions and a variety of other groups containing anything from one to three males and one to five females, with one or two young were also seen (Dague and Petter, 1988). The largest group was composed of three males, five females and one young (Dague and Petter, 1988). Meier (1987) records that L. rubriventer lives mostly in family groups of one female, one or two males and a subadult and/or juvenile animal. He also found groups containing two females and up to three males. Petter and Petter (1971) report group sizes of from five to ten individuals, while Pollock (1979) observed the Red-bellied Lemur in groups of two to four individuals. The relationships between the individuals in the groups are not clear.
The home range of Overdorffs (1988) study group, containing an adult pair and juvenile female, was 12-15 ha and their daily path length varied from 300 to 700m. The group traveled and fed as a unit, traveling within 5m of each other for 62% of the observation time and resting in contact 67% of the time; group progressions were mostly initiated and led by the adult female (Overdorff, 1988). Meier (1987) records one study group using a home range of 9 ha and the other using 75 ha. Dague and Petter (1988) found little evidence of territoriality in this species, when two groups met no aggressive or even avoidance behavior was noticed.
Activity patterns were very variable between the two months of Overdorff's study. In June the group was diurnal, whereas in July it continued feeding (on Eucalyptus flowers) into the night until as late as 23.30, i.e. five or six hours after sunset (Overdorff, 1988). In June only fruit was eaten, mostly the introduced Chinese guava, Psidium cattleyanum, while in July the lemurs spent 81% of their feeding time eating the flowers of three different species, particularly those from Eucalyptus sp; the remaining feeding time was about equally divided between eating fruit and leaves (Overdorff, 1988). Dague and Petter (1988) also found that the diet of the Red-bellied Lemur varied with the time of the year. They were never seen to eat insects, but did take flowers, leaves and fruit, particularly the latter, from around 30 different plant species (Dague and Petter, 1988). Meier (1987) confirms that fruit is taken most often; 68 different plant species were used during his study. All forest strata, including the ground, were used when L. rubriventer was feeding but the outer canopy was used most frequently (Meier, 1987).
Offspring were around 4 months old in January (Dague and Petter, 1988), which means that they were born in September or October. Meier (1987) reports a birth in mid-October. They were no longer being carried on their mother's front at that age, but they did still climb on her back for short periods (Dague and Petter, 1988). It was reported to these authors that young infants were frequently carried by the male in a group, rather than by the female, and that the older infants rested with the male more often than with their mother. Singletons are probably born most frequently, but one set of twins has been born in captivity (E. Simons, in litt.).
The major threat to this species must be the destruction of the eastern rain forests. This is caused mainly by shifting agriculture and also by logging. FAO/UNEP (1981) gave a figure of 40,000 ha of previously undisturbed closed forest cleared per year for the years 1976-80, and projected 35,000 ha for the years 1981-85; the great majority of this is expected to be in the eastern forests (IUCN/UNEP/WWF, 1987).
The Red-bellied Lemur is found in Betampona (though it is reported to be very rare there), Tsaratanana and Marojejy Nature Reserves and in Analamazaotra Special Reserve (Andriamampianina and Peyrieras, 1972; Nicoll and Langrand, 1989; Pollock, 1984; Safford et al, 1989). It is also present in the area near Ranomafana, which has been proposed as a National Park (Nicoll and Langrand, 1989; Wright, 1988) A longer term study of this species is presently being undertaken by D. Overdorff, Duke University.
All the reserves in the east in which this species occurs would benefit from better protection for this they require more guards with sufficient equipment (Nicoll and Langrand, 1989). Alternatives to using the forest for agricultural land and for fuel and building materials have to be developed if the forest is to survive and it is also important that conservation education programs are set up to help the local people understand how important the reserves and the forest are.
All species of Lemuridae are listed in Appendix 1 of the 1973 Convention on International Trade in Endangered Species of Wild Fauna and Flora. Trade in them, or their products, is subject to strict regulation and may not be carried out for primarily commercial purposes.
All Lemuroidea are listed in Class A of the African Convention, 1969. They may not, therefore, be hunted, killed, captured or collected without the authorization of the highest competent authority, and then only if required in the national interest or for scientific purposes.
Malagasy law protects all lemurs from unauthorized capture and from hunting, but this is difficult to enforce.
ISIS (June, 1989) lists a total of 13 Red-bellied Lemurs in captivity, seven males and six females. However, they place eight at Duke Primate Center and one at Columbus and give no location for the other four. Approximately two thirds of these are said to be captive born (ISIS, June, 1989).
Duke Primate Center reports that it has seven individuals in captivity of which four are wild caught and three (including one pair of twins) are captive bred (E. Simons, in litt.). There are three individuals at Mulhouse Zoo, one of which was born in captivity, and three wild caught individuals and one captive born animal at Strasbourg Université Louis Pasteur Médecine (J.-M. Lernould, in litt.). In May 1989, there were three adults and one captive born infant at Tsimbazaza Zoo (M. Pidgeon and G. Rakotoarisoa, in litt.). This information, from sources other than ISIS, indicates that there are 17 individuals in captivity of which five are captive born.
L. rubriventer is a medium sized lemur weighing about 2 kg (P. Daniels pers. comm.). Its fur is relatively long and dense, upperparts are chestnut brown, its tail is black (Tattersall, 1982). The underparts of males are dark reddish-brown while those of the females are whitish (Tattersall, 1982). For a more detailed description see Tattersall (1982), Jenkins (1987) or Petter et al (1977). The Malagasy names of this species are bari maso, tongona and soamiera (Paulian, 1981; Tattersall, 1982).