From Fruits to Leaves : Seasonal Foraging Dynamics and Nutritional Ecology of Ring-Tailed Lemurs (Lemur catta) at Berenty Private Reserve, Madagascar

Abstract

Seasonal fluctuations in food availability severely challenge the behavioral and metabolic adaptations of primates in Madagascar’s unpredictable dry forests. This study examines the nutritional determinants of foraging in the endangered ring-tailed lemur (Lemur catta) by analyzing the quantitative relationships between plant phenology, macronutrient composition, and explicit food preferences. Empirical data were collected in the "Malaza" gallery forest of the Berenty Private Reserve during two contrasting periods: November 2023 (early wet season) and July 2024 (dry season). Behavioral tracking of five adult females relied on continuous focal sampling (80 hours), while vegetation inventories and semi-quantitative phenological surveys monitored resource landscapes. Phytochemical profiles were determined via near-infrared spectroscopy (NIRS). Results reveal a profound seasonal dietary dichotomy. In November 2023, despite mature foliage dominating the available biomass (85.58%), the cohort exhibited an energy-maximizing posture, dedicating 68.00% of foraging time to scarce reproductive tissues, primarily the carbohydrate-dense fruits of Rinorea greveana and Cordia sinensis. Chemometric modeling supported this preference, displaying a moderate positive correlation with carbohydrate concentrations (r = 0.58, p = 0.0878). Conversely, the dry season in July 2024 triggered a near-total collapse of fruit availability (0.60%), forcing a structural pivot toward low-quality fallback vegetative matrices, dominated by Azadirachta indica leaves and Opuntia vulgaris stems. During this bottleneck, correlations between preferences and nutritional traits remained weak, reflecting a critical shift toward macronutrient maintenance, with slight positive trends for lipids (r = 0.374) and proteins (r = 0.232). These findings provide unequivocal evidence of evolutionary nutritional plasticity in Lemur catta. Crucially, maintaining diverse plant communities remains essential to ensure long-term population viability and micro-nutritional security within anthropogenically fragmented, spatially constrained habitats.