New distribution records and population density of the Critically Endangered Tarzan Chameleon (Calumma tarzan), eastern Madagascar

ABSTRACT

The distribution and population density of the Critically Endangered Tarzan Chameleon (Calumma tarzan) in eastern humid forests of Madagascar was studied using line transect-distance sampling. Based on the results from species distribution models, eight sites were visited over a four-month period from February 2020 to March 2021. In total, 46 transects of 1 km were investigated in 23 different forest fragments to understand the distribution of C. tarzan. Another 28 transects of 200 m in length were surveyed to estimate population density. Among the 23 investigated forest fragments, C. tarzan was confirmed from 14 fragments belonging to five sites. All 14 records are completely new and represent a significant range extension for the species. Calumma tarzan is distributed within an elevation range of 604–1048 m above sea level. An analysis of the population of the species across sites show that density varies broadly and ranges from 25 to 78 individuals per hectare. This study fills important knowledge gap on a Critically Endangered and endemic chameleon species and is vital to the development of urgently needed conservation strategy for the Tarzan Chameleon.

KEYWORDS:

• biodiversity hotspot
• conservation ecology
• conservation strategy
• distribution
• eastern humid forest
• modelling
• population ecology
• species distributions

Acknowledgements

We are grateful to the Fondation Segré Conservation Fund through the EDGE Fellowship and the Mohamed bin Zayed Species Conservation Fund (project 192521772 to A.R.) for funding this research. We are also grateful to the Malagasy authorities for issuing research permits and to the Mention Zoologie et Biodiversité Animale, University of Antananarivo for facilitating the acquisition of permit. We would also like to thank Thierry Ranomenjanahary for assisting on data collection, the local people who assisted us in various ways during fieldwork including those who prepared meals for us and served as local guides and porters.

Disclosure statement

No potential conflict of interest was reported by the author(s).