Distribution and Abundance of the World's Smallest Primate, Microcebus berthae, in Central Western Madagascar

Abstract

The distribution of most recently discovered or described lemur species remains poorly known, but many appear to have small geographical ranges, making them vulnerable to extinction. Research can contribute to future conservation actions on behalf of these species by providing accurate information on local distribution and abundance. The distribution of the world’s smallest primate, the endangered Madame Berthe’s mouse lemur (Microcebus berthae), is limited to the Menabe Central region of western Madagascar. This species was discovered in the 1990s, but many fundamental aspects of its ecology remain unknown. The aims of our study were therefore to determine the actual distribution of Microcebus berthae across the forests of this region, to estimate population density, and to examine the species’ response to anthropogenic activities. We established 35 1-km line transects across Menabe Central, on which we surveyed mouse lemurs by distance sampling and live trapping. Microcebus berthae does not occur in all remaining forests of this small region and its population density is highly heterogeneous, both across its geographic range and locally. Within its area of occupancy, the population of Microcebus berthae not only was distributed according to spatial heterogeneities of the habitat, but also responded to anthropogenic disturbances and varied seasonally. Our results indicate that Microcebus berthae is susceptible to habitat degradation and avoids human environments spatially. As none of the forest remnants in which the species still occurs were officially protected until recently, immediate conservation actions should focus on effectively protecting Kirindy and Ambadira forests.

A biogeographical perspective on the variation in mouse lemur density throughout Madagascar

“…Commonly in wildlife studies, estimation is done using capture–recapture or distance sampling (Malone et al. , Schäffler & Kappeler ; see Appendix S1).…”

“…Robust estimation of abundance or density of wild animal populations almost always requires the consideration that individuals within a sampling area will go undetected (Nichols 1992, Anderson 2001. Commonly in wildlife studies, estimation is done using capture-recapture or distance sampling (Malone et al 2013, Schäffler & Kappeler 2014; see Appendix S1). For studies conducted prior to recent species designations, we updated the species in the study to reflect the most recent taxonomy if possible.…”

“…However, the ecological drivers of the densities of those populations have been relatively unstudied (Ganzhorn et al. , exception: Schäffler & Kappeler ). It has been suggested that lemur density is higher in the western dry forests than in the eastern humid forests (Ganzhorn et al.…”

MHC class II variation in a rare and ecological specialist mouse lemur reveals lower allelic richness and contrasting selection patterns compared to a generalist and widespread sympatric congener

“…This world’s smallest primate (ca. 30 g) is endemic to the dry forests of the Menabe region in western Madagascar (Schmid and Kappeler 1994; Ganzhorn et al 2001; Schäffler and Kappeler 2014), which has recently been identified as a priority site for conservation (Schwitzer et al 2013a). The distribution of M. berthae is restricted to an area of less than 810 km 2 within two forest fragments and a narrow corridor connecting them (e.g.…”

Identifying Key Knowledge Gaps to Better Protect Biodiversity and Simultaneously Secure Livelihoods in a Priority Conservation Area

“…While the total number of species is lower in the dry than in the humid forests, species richness is exceptionally high by global comparison with other dry forests [39]. Madagascar's dry forests harbor several locally endemic vertebrate species such as Madame Berthe's mouse lemur (Microcebus berthae), the giant jumping rat (Hypogeomys antimena), the narrow-striped mongoose (Mungotictis decemlineata), and plenty of other endangered species [65][66][67][68]. M. berthae, the smallest primate in the world, is particularly vulnerable to anthropogenic disturbances and restricted to core habitats of this biome [66,69,70].…”