Greater ecological flexibility in furry-eared dwarf lemurs versus sympatric Sibree's dwarf lemurs: Insights from activity budgets, spatial distribution, and foraging behavior

Abstract

Many forests in Madagascar harbor numerous and diverse species of lemur in sympatry. Whereas more distant relatives can avoid competition by occupying distinct ecological niches, more subtle niche partitioning may explain how congeners coexist in the same place at the same time. Here, we examine the behavioral ecology of sympatric furry-eared (Cheirogaleus crossleyi) and Sibree's (C. sibreei) dwarf lemurs at Tsinjoarivo- a high-altitude rainforest in central-eastern Madagascar. Specifically, we followed 24 collared individuals during the pre- and post-hibernation seasons of 2011-2014 to determine activity budgets, spatial distribution, foraging behavior and macronutrient selection. Overall, we find that furry-eared dwarf lemurs, compared to Sibree's dwarf lemurs, had smaller home ranges and traveled shorter nightly distances, spent more time foraging and less time in their resting sites. The species were somewhat spatially differentiated, with furry-eared dwarf lemurs more often found closer to forest edges and in generally more degraded habitats. Furry-eared dwarf lemurs consumed a more diverse diet, but both species foraged for fruits (and flowers) that were rich in sugars and/or fats, key nutrients particularly during the fattening season prior to hibernation. Since this study was conducted, anecdotal observations at this site strongly suggest that the furry-eared dwarf lemur is replacing Sibree's dwarf lemur, in step with ongoing habitat fragmentation and degradation. Placing our results in broader context highlights the furry-eared dwarf lemur as a more generalist species in terms of habitat occupation, geographic distribution, and ecological flexibility. In contrast, Sibree's dwarf lemur seems to be a specialist highly adapted only to Madagascar's intact and high-elevation rainforests. If this is the case, the sympatric occurrence of these two species at Tsinjoarivo may be recent, tenuous, and unsustainable in the long run. We advocate for greater research of the behavioral ecology of sympatric dwarf lemurs at this and other sites across Madagascar.