Amphibian Diversity Monitoring during the Monsoon Season in the Western Ghats, with Special Reference to Wayanad
Abstract
The Western Ghats of India, recognized as one of the eight “hottest biodiversity hotspots” in the world, harbor an extraordinary diversity of amphibians, many of which are endemic and under varying degrees of threat. This three-year longitudinal study (2022–2025) was conducted to document, monitor, and analyze the amphibian diversity during the monsoon season across the forested landscapes of Wayanad District, Kerala. Field surveys were systematically carried out using Visual Encounter Surveys (VES) and Acoustic Monitoring Techniques across multiple habitat types, including evergreen and semi-evergreen forests, riparian zones, agricultural lands, plantations, and peri-urban ecosystems.
A total of 47 amphibian species representing 15 genera and 8 families were recorded, of which 12 species were endemic to the Western Ghats and 9 species were classified under various IUCN Red List threat categories. The monsoon season exhibited distinct patterns of species richness and abundance, peaking between June and September, corresponding to optimal breeding conditions and high humidity levels. Species composition and activity were strongly influenced by habitat heterogeneity, elevation gradients, and microclimatic factors.
Notably, the study identified microhabitats such as leaf litter zones, temporary pools, tree holes, and riparian banks as critical breeding and sheltering sites for many species. The findings emphasize the ecological significance of Wayanad’smosaic landscapes, which serve as vital refugia for amphibian populations amidst increasing anthropogenic disturbances, deforestation, and climate-induced changes in rainfall patterns.
This long-term monitoring effort provides valuable baseline data essential for formulating conservation action plans, habitat restoration strategies, and climate adaptation policies. Continued research and community-based conservation programs are imperative to safeguard the rich amphibian diversity of Wayanad, ensuring the resilience of this fragile ecosystem in the face of global environmental challenges.
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Introduction
Amphibians are among the most sensitive bioindicators of ecosystem health, owing to their permeable skin, complex life cycle, and dependence on both aquatic and terrestrial environments. Any alteration in environmental parameters—such as temperature, rainfall, water quality, or land use—can lead to significant changes in their distribution and population dynamics. In tropical regions like the Western Ghats of India, amphibians occupy an essential ecological niche, playing crucial roles in insect population control, nutrient cycling, and as prey species in complex food webs.
The Western Ghats, recognized as one of the eight “hottest biodiversity hotspots” in the world, extends along the western coast of India from Gujarat to Kerala. This mountain chain harbors exceptional amphibian diversity, with over 200 recorded species, more than 80% of which are endemic to the region. The remarkable endemism and ecological specialization of these species make them particularly vulnerable to habitat changes and climatic variability.
Wayanad district, situated in the northern part of Kerala, forms a critical ecological corridor connecting the Nilgiri Biosphere Reserve with the Coorg and Brahmagiri ranges. Its diverse topography—ranging from 700 to 2100 meters above sea level— supports a mosaic of ecosystems including tropical evergreen forests, moist deciduous forests, grasslands, and wetlands. These varied habitats, combined with high rainfall and a dense canopy cover, make Wayanad a unique refuge for amphibians, especially during the monsoon season (June–September), which triggers the majority of breeding activities and larval development.
Despite this ecological richness, the amphibian populations of Wayanad are under increasing threat. Rapid urbanization, deforestation for plantations and infrastructure, pollution from agricultural runoff, and unpredictable monsoon patterns have collectively disturbed their habitats. Changes in rainfall intensity and duration directly affect breeding pools, larval survival, and migration patterns. Additionally, the introduction of invasive species and diseases such as chytridiomycosis pose emerging challenges to native populations.
Previous studies in the Western Ghats have provided valuable insights into amphibian taxonomy and distribution. However, long-term ecological monitoring, particularly across different monsoon cycles, remains scarce. Understanding temporal variations in amphibian diversity and abundance is essential for predicting future trends under changing climatic conditions and for developing effective conservation strategies.
Therefore, this three-year observational study (2022–2025) was conducted in multiple habitats across Wayanad to monitor amphibian diversity during the monsoon season. The specific objectives were to: 1. Document amphibian diversity and species composition in selected habitats during monsoon months. 2. Assess temporal variations in species richness and abundance over three consecutive years. 3. Identify critical habitats and microclimatic factors influencing amphibian distribution, aiming to prioritize them for conservation and sustainable management.
The study adopted a combination of visual encounter surveys (VES), acoustic monitoring, and environmental parameter recording to ensure comprehensive data collection. Observations were carried out during both day and night, focusing on breeding sites such as ponds, streams, and leaf litter zones.
TABLE 1 SUMMARY OF THE THREE-YEAR AMPHIBIAN MONITORING STUDY IN WAYANAD (2022–2025)
No. of Total Observation Dominant Year Survey Species Key Observations Period Habitat Types Sites Recorded High diversity during early monsoon; June– Evergreen forest, 2022 8 28 dominance of Rhacophorus lateralis and September paddy wetlands Fejervarya limnocharis.
Moist deciduous Slight shift in species abundance; June– 2023 10 forest, riparian 31 increased sightings of Indirana spp.; September zones heavy rainfall affected breeding pools.
Mixed forest-Decline in microhabitat specialists due to June– grassland edge, 2024 12 27 drying of small ponds; increased September human-altered adaptation in generalist species. landscapes This three-year assessment offers valuable insights into how amphibian communities respond to fluctuating monsoon conditions and anthropogenic stressors in the Western Ghats. The findings will contribute to long-term biodiversity databases, help forecast amphibian population trends, and guide local conservation actions in Wayanad and similar tropical ecosystems.
Conclusion
This three-year continuous monitoring of amphibian diversity in the Western Ghats, with special
