Field testing of abundance estimation methods for monitoring mammals in tropical mountainous forests: a case study of Simbalbara Wildlife Sanctuary and Churdhar Wildlife Sanctuary, Himachal Pradesh, India

Information on the status and population estimates of species within a geographical area is vital for developing effective conservation plans. Camera traps have emerged as a promising cost-effective tool, for which numerous methods for estimating population density have been reported. Comparative tests of their applicability and performance, on the other hand, are scarce. Camera-trapping and line-transect surveys were conducted in Simbalbara Wildlife Sanctuary (SWLS) and Churdhar Wildlife Sanctuary (CWLS) to test different methods, i.e., spatially capture-recapture sampling (SECR), camera-trap distance sampling (CTDS), line transect distance sampling (LTDS), for determining species richness and density of various mammalian fauna. Camera traps recorded fifteen and twelve mammals in SWLS and CWLS, respectively. In SWLS, sambar had the highest ungulate density with 5.0 and 5.3 individuals/km ² estimated by LTDS method and CTDS method, respectively. These two methods generated a similar population for most ungulate species, indicating that both methods may be applicable in mountainous habitats. The study discusses various approaches for estimating density for identifiable and unidentifiable individuals in rugged terrain. Our findings suggest that all tested methods can work well, with each having its own strengths and weaknesses.