Identifying lemur biodiversity in lowland rainforest fragments in Madagascar

Slideshow

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Participants

  • Michael Bliss; PhD Student, Texas A&M University, USA
  • Francis Tre Lawrence; PhD Student, University of Calgary, CA
  • Patricia C. Wright; Distinguished Professor, Stony Brook University, USA
  • Jean Freddy Ranaivoarisoa; Professor, University of Antananarivo, Madagascar
  • Tafitasoa Jaona Mijoro; Director of Biodiversity Research, Catholic Relief Services, Madagascar
  • Malagasy Graduate Student; University of Antananarivo, Madagascar
  • Hajanirina Rakotondrainibe; CVB Veterinarian, Madagascar
  • Justin Solo; CVB Technician, Madagascar
  • Rakotonirina Thierry Emile; CVB Technician, Madagascar
  • Mamonofahsoavana Rinah; CVB Technician, Madagascar
  • Narindra Arinosy Elison Loret; CVB Technician, Madagascar
  • Rafanambinantsoa Tafitaniaina Jean Jacques; CVB Technician, Madagascar
  • Rasendrinirina Victore; CVB Technician, Madagascar
  • Velonabison Mamitiana; CVB Technician, Madagascar
  • Zakamanana Francois; CVB Technician, Madagascar
  • Andrianantenaina Georges Michel; CVB Technician, Madagascar

Summary

Rainforest fragments can harbor critical remnants of rare biodiversity (Otero Jiménez et al., 2023). In southeastern Madagascar, we identified the Ambodimarohita lowland rainforest fragments (21°39'41.75"S, 47°55'7.51"E), spanning approximately 450 hectares at elevations of 170–390 m. These fragments, located roughly 46 km east of the COFAV corridor and 55 km from Ranomafana National Park, have been isolated for at least 60 years due to deforestation and fire agriculture for cattle grazing. Despite these pressures, the fragments harbor at least six lemur species, including unidentified species of Eulemur, Microcebus, and Cheirogaleus. Immediate research and conservation are essential, as this forest may host species new to science, making it a critical step for Malagasy conservation.

Background

Madagascar’s biodiversity is globally significant but under severe threat from rapid deforestation (Myers et al., 2000; Schwitzer et al., 2014). Lemurs, the most endangered group of mammals, face a >90% threat rate (IUCN, 2023). Fragmented forests outside protected areas are essential refuges yet remain poorly studied. During five expeditions from 2023–2025, we have documented six lemur species in Ambodimarohita, four of which could not be identified to the species level. This suggests either unresolved taxonomy or potentially new species, underscoring the urgency of monitoring and conservation.

Methods

We conducted both daytime and nighttime line-transect surveys recording species, group composition, GPS coordinates, canopy height, distance, angle, and activity. In addition, we carried out focal follows of Eulemur spp. individuals to collect fecal samples, map ranging patterns, and record behavior at five-minute intervals. To monitor nocturnal activity and vocalizations, we installed camera traps and audio recorders every 300 meters along transects and at fruiting trees. We captured small-bodied lemurs such as Microcebus and Cheirogaleus using Sherman and Havahart traps baited with fruit slices, and Eulemur spp. to collect biological samples and take morphometric data.

Techniques

Line-transect surveys, focal follows, camera traps, acoustic monitoring, morphometrics and biological sampling, DNA analyses

Aim

Our goal is to document the extent of lemur biodiversity within Ambodimarohita, clarify the taxonomic status of species, and assess population viability. Findings will fill critical knowledge gaps about lowland rainforest lemurs, inform Malagasy conservation priorities, and contribute to strategies for protecting one of the last remaining lowland rainforest fragments in southeastern Madagascar.

Findings

Our surveys have recorded 16 mammal species, 30 species of herpetofauna, 38 bird species, and 131 plant species thus far. Among the lemurs, we confirmed the presence of Eulemur rubriventer and Microcebus rufus, while also observing unidentified species of Eulemur, Microcebus, and Cheirogaleus. Local community reports further suggest the possible presence of Hapalemur griseus. Based on our observations, fewer than 15 groups of Eulemur spp., representing roughly 60 individuals, remain in the forest. Should these individuals prove to be taxonomically distinct, this population would rank among the most endangered lemurs in Madagascar.

Conservation Steps

To protect and sustain the Ambodimarohita forest fragment and its lemur populations, we are implementing several conservation measures. We are mapping historic fires and developing a firebreak strategy to reduce risk to the forest. We are strengthening the resources available to local rangers to support their protection efforts. We are working with the local forest management group to train them in biodiversity monitoring techniques, ensuring ongoing data collection and forest stewardship when our team is not present. To support local livelihoods and reduce pressure on forest resources, we are assisting in establishing a cooperative that links agricultural products to the private sector, providing sustainable income opportunities. Finally, we are working to designate areas outside the forest fragment for firewood collection and house building, keeping human use separate from core forest habitat.

Appendix

Table. Lemur species at Ambodimarohita forest fragment (VU=Vulnerable, DD=Data Deficient)

Figure. Map of Madagascar and the forest fragments in Ambodimarohita (scaled out)

 

Figure. Map of Ambodimarohita’s established transects, our research campsites (Varovoka and Tsararano), boundary, and village center (fokotany)

Figure. Eulemur spp. males from Ambodimarohita (photo credits, Tafitasoa Jaona Mijoro)

Figure. Eulemur spp. females from Ambodimarohita (photo credits, Tafitasoa Jaona Mijoro)

Figure. Microcebus spp. from Ambodimarohita (photo credits, Tafitasoa Jaona Mijoro)

Figure. Cheirogaleus spp. from Ambodimarohita (photo credits, Tafitasoa Jaona Mijoro)

Figure. Cheirogaleus spp. from Ambodimarohita (camera trap footage)