Deer is the main prey of tigers in Nepal. To sustain deer populations – and thus tigers – we must study what the deer feed on, which should be influenced by plant species, habitat (i.e., vegetation type), season, deer species, and vegetation management (i.e., controlled burns). Therefore, the objective of Work Package 7 is to characterize in detail deer’s diet, by answering the following research questions (RQs):

1. which plants do deer eat?
2. Why do deer eat them? What nutritional quality do eaten and not-eaten plants have?
3. How does deer’s diet change across vegetation types?
4. How does deer’s diet change across seasons?
5. How does diet change across deer species?

To answer these questions, we devised a multi-methodological approach that uses direct observations in the field of deer’s feeding traces, nutritional quality analysis of plants eaten and not eaten by deer, an experimental study, and genetic analysis of deer’s faecal material.

Figure 1. Conceptual diagram, representing the research questions and the methods used to answer them in this research.

Fieldwork: Between 2022 and 2024, we conducted intensive fieldwork in Bardiya National Park, collecting observational and nutritional quality data of deer food preferences. Initial results show that deer have a nutritionally diverse diet, composed of multiple plant species and types eaten in several vegetation types. Additionally, an experiment, looking at nutritional quality changes of key plant species in relation to water availability and presence/absence of ashes remaining on the soil after fire, was successfully carried out and analysis of results is ongoing.

Figure 2: Observing deer feeding behaviour in the field Figure 3: Experiment to study plant nutritional quality (right).

Analyses and initial findings: As all chemical analyses of plant and soil material had been completed by the commercial lab in Nepal, PhD candidate Matteo Sciumbata assembled the complete dataset for at least three scientific papers. The first manuscript is based on the measurements on plant species’ abundances and nutritional quality in different predominant ecosystems in Bardiya, linked to the degree of deer herbivory on them across multiple field plots.

An important finding from this work is that the diet of the predominant chital deer is very diverse, based on the fact that they spend much time foraging in the forest, where they feed not only on grasses, but also on many different plants of high apparency (relative abundance), while also targeting certain specific species of herbs and woody plants that are less abundant. Many of the much-eaten plant species and types turned out to have low nutritional value, possibly to achieve a balanced overall diet. These findings emphasize the view that protection of the grasslands for food provisioning to deer (as prey for tigers) cannot be effective without large expanses of the adjacent forest.

The second manuscript  is based on the results of the outdoor nursery experiment in which the growth and nutritional quality (from the perspective of chital and other deer) of four key plant types from forest and grassland were measured in response to different relevant soil regimes: (a) soil with (A+) versus without fresh ash (A-) remaining from a fire added and (b) dry (W-) versus moist (W+) soil conditions.

Research findings support the view that protection of the grasslands for food provisioning to deer (as prey for tigers) cannot be effective without large expanses of the adjacent forest. Matteo presented posters about the findings from the first study at the Netherlands Annual Ecology Meeting (NAEM 2025) and at the European Conference for Tropical Ecology (ECTE 2025). He also made his field data available for the vegetation upscaling in WP 9.

Future work: We will perform genetic analysis of deer’s faecal material in autumn 2026 to calibrate different methods and provide an in-depth analysis of deer’s diet. Genetic analysis faces some struggles in remote areas, where lab facilities are not available, but a new portable genetic screening device may change things!

For further findings, we are preparing new work together with WP 8 on assessing (plant) food choice of Bardiya deer via genetic analysis of their pellets, and linking the genetic identity to plant species collected there.

Figure 3: Part of the research team in the field.

Young researchers involved: PhD studentMatteo Sciumbata (Vrije Universiteit Amsterdam (VU), The Netherlands); MSc students Laya Thapaliyalaya (Tribhuvan University, Nepal), Suyog Neupane (Forest Research Institute Dehradoon, India), and Sakshi Palimar (VU).