Stable isotopes complement focal individual observations and confirm dietary variability in reddish–gray mouse lemurs (Microcebusgriseorufus) from southwesternMadagascar

Abstract

We examine the ecology of reddish-gray mouse lemurs from three habitats at Beza Mahafaly Special Reserve using focal follows and stable carbon and nitrogen isotope data. Focal observations indicate dietary differences among habitats as well as sexes and seasons. Both sexes consume more arthropods during the rainy season but overall, females consume more sugar-rich exudates and fruit than males, and individuals from riparian forest consume fewer arthropods and more fruit than those in xeric or dry forest. We ask whether these observations are isotopically detectable. Isotope data support differences between seasons and sexes. Nitrogen isotope values are higher during the rainy season when lemurs consume more arthropods, and higher in males than females, particularly during the dry season. However, differences among populations inferred from focal observations are not fully supported. Lemurs from riparian forest have lower isotope values than those in xeric scrub, but isotope data suggest that lemurs from the dry forest eat the least animal matter and that focal observations overestimated dry forest arthropod consumption. Overall, our results suggest that observational and isotopic data are complementary. Isotope data can be obtained from a larger number of individuals and can quantify ingestion of animal matter, but they apparently cannot quantify the relative consumption of different sugar-rich foods. Combined focal and isotope data provide valuable insight into the dietary constraints of reddish-grey mouse lemurs, with implications for their vulnerability to future habitat change.

Stable isotope variation in savanna chimpanzees (Pan troglodytesverus) indicate avoidance of energetic challenges through dietary compensation at the limits of the range

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“…However, in larger‐scale comparisons of δ 13 C and δ 15 N values across multiple ecological conditions potential conclusions become less straightforward. Initial studies attempted to evaluate aspects of primate diet and ecology using tissue samples alone, yet the recognition of the variability of tropical ecosystems led researchers to embrace the incorporation of environmental context into cross‐site comparisons (Crowley et al, ; Oelze et al, ; Oelze et al, ). For example, one prominent contextual measure of isotope system variability was mean annual precipitation (MAP).…”

Comparative isotope ecology of African great apes

“…Thus, every location should have a unique plant isotope baseline. Recently, Crowley and colleagues (Crowley et al, 2014) suggested calculation of a mean isotope ratio of a standardized vegetation sample (e.g. only C3, non-leguminous plants)…”

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“…A look through the major journals in 2014 shows the diversity of field and study contexts in which biological anthropologists are embedded. For example, a single issue of the American Journal of Physical Anthropology (September 2014) includes the following: articles describing primate biology in Ethiopia (Fashing et al ), Madagascar (Crowley et al ), and the Philippines (Smith et al ); articles investigating the relationships of historic and prehistoric human populations in southern Africa (Irish et al ) and Southeast Asia (Matsumura and Oxenham ); articles looking at issues of health or developmental biology in prehistoric Aboriginal Australians (Durband ), Irish famine victims (Geber ), French Neandertals (Garralda et al ), Dutch children (Vucic et al ), and Kenyan pastoralists (Iannotti and Lesogorol ); articles examining biomechanical issues in skeletal material from southern South America (Menéndez et al ), Romania (Webb et al ), and medieval France (Le Luyer et al ). …”