Census of brown lemurs (Eulemur fulvus sspp.) in southeastern Madagascar: methods-testing and conservation...

Area of Science:

• Primatology
• Conservation Biology
• Ecology

Background:

• Two threatened brown lemur subspecies, Eulemur fulvus collaris and Eulemur fulvus albocollaris, inhabit southeastern Madagascar.
• Assessing population densities and habitat conditions is crucial for their conservation.

Purpose of the Study:

• To estimate local population densities and assess habitat conditions for Eulemur fulvus collaris and Eulemur fulvus albocollaris.
• To evaluate the effectiveness of transect survey methods for lemur population estimation.

Main Methods:

• Field surveys were conducted in four forest areas in southeastern Madagascar using transect methods.
• Transect lengths and surveillance frequencies were varied, with comparative tests at Parc National de Ranomafana.
• Liana density and habitat characteristics were assessed alongside lemur population counts.

Main Results:

• Transect surveys using existing trails provide close estimates of lemur population size, with precision increasing with more replications and longer transects.
• Eulemur fulvus albocollaris exhibited significantly lower population densities (0.086 animals/ha) compared to Eulemur fulvus collaris (0.107 animals/ha) at Midongy-Sud.
• Habitat degradation, including fragmentation, reduced forest area, logging, and hunting, was more severe in E. f. albocollaris's range.

Conclusions:

• Eulemur fulvus albocollaris populations are critically low and face severe habitat threats, necessitating immediate conservation interventions.
• Habitat quality, indicated by liana density, may influence lemur population density.
• Conservation strategies must address habitat fragmentation, degradation, and direct threats like hunting for E. f. albocollaris.