FISSION-FUSION IN EULEMUR FULVUS RUFUS IN SOUTHEASTERN MADAGASCAR |
| D. J. Overdorff; E. M. Erhart and T. Mutschler University of Texas-Austin, Dept. of Anthropology, Univ. of Texas, E.P.S. C3200, 1 University Station, Austin, TX, 78712, USA |
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| In a previous long-term study of red-fronted lemurs (Eulemur fulvus rufus) at the Ranomafana National Park, Madagascar (Overdorff et al 1999), E. f. rufus was described as having groups ranging between 6-16 individuals (mean = 9.5) with a high degree of group stability and cohesion. In seven years, only 21 individuals either immigrated (n = 3) or emigrated (n = 18) and eighteen of these cases involved adult males. Since this study was published, several interesting differences have been noted, particularly regarding group stability and cohesion. Overall study groups are smaller (mean = 6.8 inds) and over the last 21 months, 13 immigrations/emigrations have been noted involving almost an equal number of adult males (n = 6) and females (n = 7). Additionally, groups are less cohesive; fission-fusion has been observed regularly in June and July when food is least available. Groups are also less faithful to their home ranges. Both study groups have been observed 7-8 km away from the main study site, often for months at a time. These differences may be related to extreme fluctuation in food availability and increases in population density of red-bellied lemurs (Eulemur rubriventer) and ruffed lemurs (Varecia variegata) that compete for many of the same fruiting and keystone resources. |
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