Decoding Deer Dining: A study on plant preference and foragingpatterns of deer in Bardia National Park, Nepal

Congratulations to Sakshi Rao Palimar, a master student from Vrije Universiteit Amsterdam (VU) who recently finished his Master thesis on plant preferences for Deer in the Bardia National Park.

This study aims to understand the dietary preferences of chital (Axis axis), a staple prey for tigers, in Bardia National Park (BNP), Nepal, focusing on vegetation type, plant type, plant cover, and plant functional traits such as specific leaf area (SLA) and leaf dry matter content (LDMC). Previous studies predominantly focus on deer diets in phantas (anthropogenic grasslands), leaving a gap in knowledge about their preferences in forests. Through field observations and systematic quantitative analyses, vertebrate herbivory damage (VHD) was assessed across different vegetation types and plant categories. The hypothesis of the study is that chital would prefer plants with tender foliage (higher SLA and lower LDMC), across vegetation types. However, contrary to the posited hypothesis, both plant functional traits, specific leaf area (SLA) and leaf dry matter content (LDMC) did not significantly influence chital diet selection of understorey plants. Instead, significant differences were found in VHD based on vegetation type, plant type, and plant cover. Chital preferred mixed hardwood and riverine forests over phantas and sal forests, with the highest VHD in mixed hardwood forests. Grasses, saplings, and sedges experienced the highest VHD, indicating strong preference, while climbers and ferns showed minimal damage. Intermediate plant cover ranges (5-12.5%) suffered the most damage, suggesting that plant apparency influences foraging behavior to an extent. Direct observations revealed that deer frequently feed on leaves dropped by langurs and fallen leaf litter, and expend extra energy to access certain understory plants, indicating strong preferences for specific species. Some abundant plants, like ferns, were not eaten, suggesting other factors like nutritional quality and chemical defenses influence diet selection. This research enhances understanding of herbivore-plant interactions in tropical ecosystems and provides insights for effective management and conservation strategies in BNP. Maintaining diverse and rich vegetation types may be important for supporting a stable prey base for predators such as tigers, thus aiding in the conservation of both herbivores and their predators while mitigating human-wildlife conflict.