Comparative activity pattern analysis of endemic chevrotains in Sri Lanka

Chevrotains are the most primitive ruminants, with few species surviving globally. Sri Lanka has two endemic species: Moschiola meminna in the dry zone and Moschiola kathygre in the wet zone. Data on their activity patterns are lacking due to their elusive nature. To address this knowledge gap, we conducted a comparative analysis of their activity patterns using camera trap surveys in Wilpattu National Park (WNP) for M. meminna and Sinharaja Forest Reserve (SFR) for M. kathygre. We placed camera traps covering >30% of each habitat type present in both study areas using a systematic random survey method. Camera trap timestamps were used to analyze the activity patterns. Time data were converted to radian time for cyclical time representation before analysis. Using the R package ‘activity’, species-specific activity levels and the proportion of the diel cycle during which each species was active were quantified. Activity level estimates were generated through 1,000 bootstrap iterations, with non-parametric von Mises kernel density estimators used to model the probability density functions of activity peaks. The analysis showed that the overall activity level of M. meminna in WNP was 0.50 (SE: 0.08). The activity pattern was recorded across multiple time intervals, with distinct peaks at 0400, 1100, and 1800 hrs. This suggests a cathemeral strategy, possibly to avoid midday heat while balancing foraging and predator avoidance. The lowest activity was recorded at 1500 hrs. The activity level of M. kathygre in Sinharaja was estimated at 0.39 (SE: 0.04). The activity pattern revealed distinct peaks of presence at 0400 and 2000 hrs, showing a nocturnal activity pattern. This behaviour is typical of forest ungulates that evade daytime predators and human activities. Their nocturnal habits may suggest competition with other herbivores or heightened sensitivity to disturbances in fragmented habitats. The higher overall activity level of M. meminna compared to M. kathygre suggests greater diurnal activity in open habitats (WNP) versus dense forests (SFR). These findings emphasize the importance of species-specific conservation strategies to protect Sri Lanka’s endemic chevrotains. For M. kathygre, reducing human disturbance during nocturnal hours is crucial to maintain natural activity rhythms. For M. meminna in the dry zone, conservation should prioritize preserving thorn and dry mixed evergreen forests, along with habitat features such as litter cover that provide refuge and foraging resources.