# Trophic Ecology of a Threatened Specialist: Implications of the Dependence on Pappostipa frigida for the Conservation of Chinchilla chinchilla

## TL;DR

This study shows that the endangered short-tailed chinchilla relies heavily on one plant species, Pappostipa frigida, making it highly vulnerable to habitat changes and emphasizing the need to protect these grasslands.

## Contribution

The study provides the first detailed annual analysis of the short-tailed chinchilla's diet and trophic specialization in the wild.

## Key findings

- The chinchilla's diet is dominated by Pappostipa frigida, with over 77% of its food coming from this single grass species.
- The species shows strong and consistent positive selection for Pappostipa frigida across all seasons.
- The low dietary diversity and high specialization highlight the chinchilla's vulnerability to environmental changes and habitat loss.

## Abstract

This study assesses the diet and trophic specialization of the short-tailed chinchilla (Chinchilla chinchilla), a critically endangered species from the Chilean Andes. The results show a strong dependence on a single plant resource (Pappostipa frigida), evidencing its vulnerability to changes in high-Andean vegetation and highlighting the need to conserve these grasslands.

Understanding trophic ecology is fundamental for the conservation of threatened species with specialist trophic strategies, such as the short-tailed chinchilla (Chinchilla chinchilla), a critically endangered rodent whose diet in the wild is poorly understood. This study presents the first integrated annual characterization of the dietary habits, trophic niche, and resource selection patterns of a high-Andean population. Plant availability was assessed, and dietary composition was analyzed via seasonal microhistological analysis of fecal samples. Diversity (Shannon-Wiener, H′), overlap (Schoener, PS), and resource selection (Manly’s selection index) metrics were calculated. The results indicate a diet of very low diversity (H′ < 0.1), stable throughout the year (PS > 0.99), and dominated (>77%) by grass Pappostipa frigida, with significant positive selection in all seasons. Shrub species, such as Adesmia frigida, were consistently avoided. This high degree of specialization reflects low functional plasticity and highlights the high vulnerability of C. chinchilla to environmental changes and habitat loss, underscoring that the conservation and restoration of P. frigida grasslands are imperative for the species’ survival. Microhistological methodology is confirmed as a key tool for identifying critical trophic relationships and supporting conservation plans based on essential resources.