# Behavioral Plasticity of Rewilding Milu in Mountainous Region of Northern China

## TL;DR

This study examines how Milu deer adapt their behavior when rewilded in a cold mountainous region, showing significant changes in movement and activity patterns.

## Contribution

The study provides new insights into the behavioral plasticity of Milu in harsh environments, which is crucial for rewilding strategies.

## Key findings

- Milu showed seasonal and sex-based differences in home range and movement distance.
- Activity rhythms stabilized three months after release, with crepuscular patterns observed.
- The study provides a scientific basis for managing Milu populations in cold-temperate environments.

## Abstract

There is limited research on the behavioral adaptability of rewilding endangered species into relatively harsh environments. Historically, Milu (Elaphurus davidianus) primarily inhabited warm, humid low-altitude plains and wetlands. In 2021, 27 Milu were introduced into the mid-altitude Daqing Mountains of Inner Mongolia. This study aims to reveal the behavioral adaptability of Milu under harsh environmental conditions. The results indicated that after rewilding into the Mongolian Daqing Mountains, the Milu exhibited strong behavioral plasticity in terms of home range size, movement distance, and circadian rhythms.

Species rewilding, as a key strategy for rescuing endangered species and rebuilding wild populations, fundamentally relies on the behavioral plasticity of specific wildlife species. Although most current rewilding initiatives select optimal habitats, research on behavioral adaptation mechanisms in more challenging, extreme environments remains lacking. The Milu (Elaphurus davidianus), a typical wetland and plain species, naturally inhabits the warm marshlands of the Yangtze and Yellow River basins. In this study, using GPS tracking data, we focused on a population of rewilding Milu on the Inner Mongolia Plateau to investigate behavioral plasticity in terms of home range area, activity rhythm, and movement distance, aimed to elucidate their survival adaptation strategies within mid-elevation and cold environments. The results indicated significant seasonal and sex-based differences in both home range and movement distance: home ranges contract and movement distances are minimized during winter, while spatial activity expands markedly in summer—and continues to increase year by year following rewilding. During the study period, the number of daily activity peaks per individual ranged from zero to four. Furthermore, peak timing exhibited clear seasonal variation, with crepuscular patterns—morning and evening activity peaks—predominant across most months. Approximately three months after release, the activity rhythms of both males and females stabilized. These findings reveal key behavioral adjustments of Milu translocated to a mountainous, cold-temperate environment outside its original distribution range, and provide a scientific basis for long-term management and for assessing the ecological adaptability of this introduced population.