# Specialized Feeding Behavior of an Endangered Primate Enhances Forest Health in China

## TL;DR

An endangered monkey's diet on a specific lichen helps control its growth, which in turn supports forest health and resilience.

## Contribution

The study reveals how a specialized primate diet can regulate lichen biomass and promote ecosystem stability.

## Key findings

- Lichen-covered branches showed higher dieback rates, indicating harm to host trees.
- Lichen biomass tripled in habitats where the monkey species vanished 40 years ago.
- Monkey feeding activities may enhance lichen dispersal and growth.

## Abstract

A study on the long‐term ecological impacts of specialized behavior can provide valuable insights for biodiversity conservation and ecosystem management, particularly in the context of climate change. The endangered primate
Rhinopithecus bieti
in temperate forest ecosystems relies primarily on the lichen
Usnea longissima
as its fallback food source. To investigate whether this specialized diet sustains forest health through trophic interactions, our study employed a three‐tiered approach: (1) We first examined the impact of
U. longissima
on trees by comparing the health of branches covered with and without lichen. Findings reveal
U. longissima
exhibits harm to host trees, as lichen‐covered branches displayed significantly higher rates of dieback. (2) Using habitats with varying extinction timelines of
R. bieti
, we quantified how the presence of
R. bieti
contributes to reducing
U. longissima
biomass. Results showed lichen biomass tripled in habitats where the species vanished 40 years ago compared to occupied habitats. (3) We finally used controlled artificial experiments that demonstrated that
R. bieti's feeding activities may enhance
U. longissima
dispersal and growth. Our findings suggest that
R. bieti
may function as a natural regulator of lichen biomass, potentially helping to prevent overgrowth that could destabilize forest health. Notably, the monkeys' foraging behavior may not only control lichen proliferation but also help to promote its regeneration. This study underscores that restoring
R. bieti
populations would synergistically benefit both
U. longissima
viability and forest resilience, advocating for integrated conservation strategies that preserve specialized ecological interactions. Due to the fact that specialized diet species face severe survival challenges in the context of climate and environmental changes, future efforts should be focused on their ecological adaptation mechanisms and improving sustainable management strategies.

The endangered black‐and‐white snub‐nosed monkey (
Rhinopithecus bieti
) exhibits a specialized diet on the lichen
Usnea longissima
. We proved that the
U. longissima
is harmful to trees and the monkey mitigates overgrowth of the lichen, as well as promotes its regeneration to maintain population, thereby promoting ecosystem health and resilience. This finding underscores that specialized behaviors may fulfill critical ecological roles, and should be incorporated in ecosystem‐based conservation strategy.