Preliminary Study of the Conservation Status of Lemur Communities in the Betsakafandrika Region of Eastern Ma- dagascar

Regions where lemur subspecies are sympatric or hybridize are of great interest to scientists and conservation authorities. If two subspecies of lemur are sympatric and do not interbreed, then both may warrant recognition at the species level. Such taxonomic changes have important implications for conservation authorities. If the lemur subspecies interbreed, then they form a hybrid zone. There are, however, few published accounts of primate hybrid zones, and only two for lemurs (Meyers et al. 1989; Sterling and Ramaroson 1996; S. Johnson, pers. com.). Preliminary surveys by Goodman and Schütz (1999) north of the Onive River at Mahatsinjo forest observed the nominate form of diademed sifakas (Propithecus diadema diadema) nearly daily and no Milne-Edward’s sifakas (P. d. edwardsi). However, the possibility of a sifaka hybrid zone in the region was suggested by a recent Duke expedition that captured two females and a male sifaka (K. Glander, pers. comm.). Rakotondraparany (1997) suggested that there may be a hybrid zone between common brown lemurs (Eulemur fulvus fulvus) and red-fronted brown lemurs (E. f. rufus) in his survey between Tsinjoarivo and Ambatolampy, while Goodman and Schütz (1999) observed only E. f. fulvus at both Mahatsinjo and Anilahila. Survey data in the Onive River basin are also of interest because it has been suggested that this river limits the range of Indri (Indri indri), two subspecies of brown lemur (E. f. fulvus and E. f. rufus), red-bellied lemurs (Eulemur rubriventer), and P. d. diadema and P. d. edwardsi (e.g., Tattersall 1982; Mittermeier et al. 1994; Garbutt 1999; Goodman and Schütz 1999). Although surveys have been conducted north of the Onive River (Goodman and Schütz 1999) and 35 km south of the Onive River (Irwin et al., this volume), there are few data on lemur communities in the forest region immediately south of the Onive River. Given the seemingly conflicting status of the Onive River as either an area of lemur sympatry/hybridization or barrier to lemur distribution, survey data are needed to help resolve some of the issues associated with this region. The goal of our project was to determine the community structure of primates in forests south of the Onive River. Specifically, we wanted to: (1) document the diversity of sifakas and other lemurs and (2) determine if there are hybrid zones or areas of sympatry for P. d. diadema and P. d. edwardsi as well as other lemur species.