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The Critically Endangered blue-eyed black lemur Eulemur flavifrons of north-western Madagascar is one of the most threatened primates. The majority of research and conservation efforts for the species have been restricted to the Sahamalaza Peninsula but there are unstudied and unprotected populations farther inland. The dearth of information regarding the transition between E. flavifrons and its parapatric sister species, the Vulnerable black lemur Eulemur macaco, and the possibility of a hybrid population complicates conservation planning for both species. We surveyed 29 forest fragments across both species’ ranges to investigate the boundary between the taxa, whether hybrids persist, and the threats to lemurs in the region. We found E. flavifrons in six fragments and E. macaco in 17. We never observed E. flavifrons and E. macaco in the same location and we found no conclusive evidence of hybrids. Three fragments in which E. flavifrons was present were north of the Andranomalaza River, which had previously been considered the barrier between the two species. Based on these observations and a literature review, we provide updated ranges, increasing the extent of occurrence (EOO) of E. flavifrons by 28.7% and reducing the EOO of E. macaco by 44.5%. We also evaluate the capacity of protected areas to conserve these lemurs. We recommend additional surveys and the implementation of an education programme in this region to help conserve both species.

Primates worldwide are faced with increasing threats making them more vulnerable to extinction. Anthropogenic disturbances, such as habitat degradation and fragmentation, are among the main concerns, and in Madagascar, these issues have become widespread. As this situation continues to worsen, we sought to understand how fragmentation affects primate distribution throughout the island. Further, because species may exhibit different sensitivity to fragmentation, we also aimed to estimate the role of functional traits in mitigating their response. We collated data from 32 large-bodied lemur species ranges, consisting of species from the families Lemuridae (five genera) and Indriidae (two genera). We fitted Generalized Linear Models to determine the role of habitat fragmentation characteristics, for example, forest cover, patch size, edge density, and landscape configuration, as well as the protected area (PA) network, on the species relative probability of presence. We then assessed how the influence of functional traits (dietary guild, home range size) mitigate the response of species to these habitat metrics. Habitat area had a strong positive effect for many species, and there were significantly negative effects of fragmentation on the distribution of many lemur species. In addition, there was a positive influence of PAs on many lemur species' distribution. Functional trait classifications showed that lemurs of all dietary guilds are negatively affected by fragmentation; however, folivore-frugivores show greater flexibility/variability in terms of habitat area and landscape complexity compared to nearly exclusive folivores and frugivores. Furthermore, species of all home range sizes showed a negative response to fragmentation, while habitat area had an increasingly positive effect as home range increased in size. Overall, the general trends for the majority of lemur species are dire and point to the need for immediate actions on a multitude of fronts, most importantly landscape-level reforestation efforts.

McConnell and Kull question whether the current forest habitat represents “only 10 to 20% of Madagascar's original forest cover.” We agree that it would have been more prudent to replace “original forest cover” with “surface.” We also concur that there is palaeoecological evidence for