21The diversity of qualitative approaches and analytical methods has often undermined 22 comparative research on primate vocal repertoires. The purpose of the present work is 23 to introduce a quantitative method based on dynamic time warping to the study of 24 repertoire size in Eulemur spp. We obtained a large sample of calls of E. coronatus, 25 E. flavifrons, E. fulvus, E. macaco, E. mongoz, E. rubriventer and E. rufus, recorded 26between 1999 and 2013 from captive and wild lemurs. We inspected recordings 27 visually using spectrograms, then cut and saved high-quality vocal emissions to single 28 files for further analysis. We extracted the acoustic features of all vocalizations of a 29 species using the Hidden Markov Model toolkit, an application of dynamic time 30warping, then compared cepstral coefficients (a feature widely used in automatic 31 speaker recognition) pairwise. We analysed the results using Affinity Propagation 32 clustering. We found that Eulemur species share most of their vocal repertoire but 33 species-specific calls determine repertoire size differences. Repertoire size varied 34 from 9 and 14 vocalisation types among species, with a mean of 11. Group size is 35 thought to favour the evolution of vocal complexity at the species level but our results 36 suggest that this relationship should be reconsidered, as Eulemur rubriventer has the 37 largest vocal repertoire but shows a relatively small average group size when 38 compared to congeneric species.

We recorded vocalisations of wild Eulemur mongoz groups in Madagascar and the Comoros Islands, as well as from habituated captive groups housed in European and Madagascan zoos. Each vocalisation was quantitatively described by means of an acoustic analysis procedure implemented in Praat, and vocal types were distinguished both by ear and by the visual screening of spectrograms. Vocal signals were then associated with the context in which they were produced, to explore whether they occur only in specific behavioural contexts or are uttered in a range of situations. We found that mongoose lemurs possess highly context-specific aerial alarm calls and territorial calls, while the 'croui-croui' is usually emitted to communicate between individuals regrouping at sunset. The other calls we recorded, such as those including low-pitched pulse trains sometimes followed by harmonic elements, were not tightly associated with a particular context. Mongoose lemur utterances included calls produced with closed mouths and the involvement of nasal resonance, or with constant degrees of mouth opening or mandible 'articulation' during phonation. We observed 15 vocal types, nine of which were entered into a multivariate model that classified vocal types with a high degree of reliability. The second and third formants played an important role in discriminating among types of calls.

The decline of the mongoose lemur Eulemur mongoz has resulted in a change of its conservation status from Vulnerable to Critically Endangered. Assessing the current threats to the species and the attitudes of the people coexisting with it is fundamental to understanding whether and how human impacts may affect populations. A questionnaire-based analysis was used to study the impact of agriculture and other subsistence activities, and local educational initiatives, on lemur abundance, group size and composition in the Comoros. On the islands of Mohéli and Anjouan we recorded  lemurs in  groups, the size and composition of which depended both on environmental parameters and the magnitude and type of anthropogenic pressure. There was no evidence of an impact of anthropogenic disturbance on abundance. In contrast, group size and composition were sensitive to human impacts. The most important threats were conflicts related to crop raiding, as well as illegal capture and hunting. The promotion of educational activities reduced the negative impact of hunting and illegal activities. These results highlight a need for urgent conservation measures to protect the species.