Niche overlap across landscape variability in summer between two large herbivores using eDNA metabarcoding

Area of Science:

• Ecology
• Zoology
• Conservation Biology

Background:

• Understanding species feeding strategies (trophic ecology) is crucial for environmental management.
• Quantifying diet composition reveals species' environmental use and niche overlap.
• Previous studies often overlook landscape variability's influence on herbivore diets.

Purpose of the Study:

• To explore how landscape variability influences diet composition and niche overlap in red deer (Cervus elaphus) and European bison (Bison bonasus).
• To investigate the effects of habitat quality and predation risk on the diet composition and niche partitioning of these large herbivores.

Main Methods:

• Utilized eDNA metabarcoding to quantify the plant composition of red deer and European bison diets.
• Analyzed diet data in relation to habitat quality (deciduous forage abundance) and predation risk (wolf density) in Bialowieza Forest.

Main Results:

• Diet composition varied significantly across the landscape for both species.
• Red deer exhibited greater diet variability and lower within-species niche overlap than bison.
• Increased predation risk led to reduced niche overlap and more dissimilar diets in red deer, suggesting behavioral changes due to wolf presence.
• Higher habitat quality correlated with increased niche overlap only in bison, likely due to their browsing strategy.

Conclusions:

• Species' diet composition is not uniform across landscapes and is influenced by environmental factors.
• Predation risk and habitat quality play distinct roles in shaping the trophic ecology and niche partitioning of large herbivores.
• Integrating environment-induced diet variations is essential for accurate assessments of landscape usage and niche overlap in ecological studies.