114 L. D. Martin et al.


regional differences in habitat (e.g. increased fragmentation and seasonality in western dry forests), species richness and mouse lemur physiology, amongst other factors (Setash et al., 2017). Consistent with these large-scale regional pat- terns, and as predicted, M. mamiratra densities were broad- ly similar to those reported for other species from the dry and transitional forests of north-west Madagascar. For ex- ample, densities of 30 individuals/km2 have been reported for what is probably the Sambirano mouse lemur Microcebus cf. sambiranensis at Sahamalaza-Iles Radama National Park (Hending et al., 2022b), 378 individuals/km2 for Danfoss’ mouse lemur Microcebus danfossi in the Sofia region (Randrianambinina et al., 2010; Hending et al., 2022b) and 80 and 265 individuals/km2 for the northern rufous mouse lemur Microcebus tavaratra at various sites in the Daraina region (Meyler et al., 2012). Although M. mamiratra has been described, at least anecdotally, as rare within its range (Mittermeier et al., 2010; Blanco et al., 2020; see also McKelvey et al., 2008), our results indi- cate this is not the case, at least for the Nosy Be population, insofar as rarity relates to low abundance (Drever et al., 2012). The misconception that M. mamiratra is rare could relate to its low detectability; mouse lemurs are small, most- ly solitary, inconspicuous and can be difficult to detect at distance, particularly in dense forest and wet weather (Fig. 2; Schäffler&Kappeler, 2014; Deppe, 2020). This serves to highlight the value of distance sampling methods that model and incorporate detectability and only require perfect detection on the transect centre line or point. Our survey area included protected and unprotected


areas and several habitat types, covering much of the extent of occurrence of M. mamiratra on Nosy Be. As predicted, the transects with the highest encounter rates were in un- protected secondary and degraded forests in the north-west of our survey area, outside the Lokobe National Park bound- aries and proximate to areas of human activity (Table 1; Fig. 1). This suggests that M. mamiratra, similarly to other mouse lemurs, may prefer disturbed forests and anthro- pogenic habitats. Mouse lemurs are generally highly adapt- able and can be common in such habitats, including agricultural crops (Hending et al., 2018; Knoop et al., 2018; Andriambeloson et al., 2021). Unlike other cheiro- galeids, mouse lemur density generally has a positive rela- tionship with anthropogenic disturbance and a negative relationship with forest cover, and densities are generally higher in unprotected than protected areas (Hending, 2021). Moreover, some mouse lemurs show tolerance to forest edges, a common microhabitat feature of the frag- mented secondary and degraded forests in our study site (Lehman et al., 2006; Burke & Lehman, 2015). We also ob- served that the transects with high encounter rates were ad- jacent to transects where M. mamiratra was never or seldom observed (Table 1; Fig. 1). It has also been found that en- counter rates of M. mamiratra are highly variable


(Tinsman et al., 2022). This uneven spatial distribution may be explained by variation in forest microhabitat struc- tures that are important to mouse lemur survival (Rendigs et al., 2003; Fredsted et al., 2004).


Conservation recommendations and future directions


Nosy Be is a priority area for lemur conservation, and our results indicate that its population of M. mamiratra com- prises c. 4,700 individuals at a moderately high density. Importantly, the highest encounter rates occurred in the un- protected secondary and degraded forests surrounding Lokobe National Park, some of which are managed by Vondron’Olona Ifotony (Fig. 1), a village-based association for forest management. We encourage conservation man- agers to continue to work with local communities and pri- vate landowners to preserve all remaining forest habitats. Several landowners and village presidents we spoke with during informal discussions expressed an interest in lemur conservation; for example, some landowners maintained small forested areas on their plantations having observed le- murs using them. Direct payments to households could help incentivize forestmanagement and ensure local people are adequately compensated for the high opportunity costs borne through conservation restrictions (Milne & Niesten, 2009; Wendland et al., 2010; Gross-Camp et al., 2012; Schwitzer et al., 2013; Poudyal et al., 2018; Estrada et al., 2022). However, this would require significant, long-term investment, typically from international donors, and such schemes have so far achieved only limited success in Madagascar (Sommerville et al., 2010; Rasolofoson et al., 2015). Because Nosy Be is a popular tourist destination, there is also potential for nocturnal lemurwatching ecotour- ism to help protect lemur habitat, generate income for local communities and foster residents’ appreciation of lemurs (Ormsby & Mannle, 2006; Schwitzer et al., 2014; Wright et al., 2014; Waters et al., 2023). Madagascar National Parks has recently commenced nocturnal tours at Lokobe National Park (G. Bakarizafy, pers. comm., 2023), and with the support of local stakeholders this could be extended to community-led initiatives outside the Park (Razanatsoa et al., 2021). The conservation success stories of community-run organizations elsewhere in Madagascar (e.g. Association Mitsinjo in Andasibe and Anja Reserve in the south-central highlands) could be emulated in Nosy Be by integrating ecotourism with other initiatives, includ- ing forest restoration, scientific training and capacity build- ing, and environmental education (Schwitzer et al., 2013; Dolch et al., 2015; Gould & Andrianomena, 2015). Currently, Lokobe National Park is the only protected


area in which M. mamiratra occurs (Blanco et al., 2020). Although the Park has good infrastructure and is well re- sourced, it is small, and it is doubtful whether it alone can ensure the long-term viability of the species (Olivieri et al.,


Oryx, 2025, 59(1), 109–118 © The Author(s), 2025. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000772


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