Diet composition and selection of Père David's deer in Hubei Shishou Milu National Nature Reserve, China

Hubei Shishou Milu National Nature Reserve is an ideal place to restore the wild population of Père David's deer (Elaphurus davidianus). Understanding foraging ecology and diet composition is essential for assessing population development or establishing long-term effective conservation measures for endangered species. However, little is known about the diet composition of Père David's deer and its diet selection mechanism. In this study, we used stable isotope technology to investigate the diet composition of Père David's deer according to various tissues (i.e., fur, muscle, liver, heart, and feces) and seasons, and evaluated the correlation between the nutrient composition of plants and diet composition. Bayesian isotope analysis showed that the autumn and winter diet estimated by fur and fecal samples indicated a diet dominated by C3 grasses (42.7 to 57.2%, mean), while the summer diet estimated by muscle and liver samples was dominated by C3 forbs (30.9 to 41.6%, mean). The Pearson correlation test indicated that the contribution of winter diet composition reflected by fur and fecal samples was associated with correlations with crude protein (r = 0.666, P < 0.01) and soluble sugars (r = 0.695, P < 0.01). The results indicated that crude protein and soluble sugars were important factors influencing the winter diet selection of Père David's deer. In the context of the current reintroduction facing many challenges, such as habitat fragmentation, wetland degradation, and human disturbance, comprehensively evaluating the diet selection mechanism of Père David's deer under different resource specificities and temporal changes should be considered in the future.湖北石首麋鹿国家级自然保护区是恢复野生麋鹿（Elaphurus davidianus）种群的理想场所。探明麋鹿的觅食生态学特征与日粮组成，对于评估其种群发展态势，或制定针对该濒危物种的长期有效保护措施至关重要。然而，目前学界对麋鹿的日粮组成及其食性选择机制仍知之甚少。本研究采用稳定同位素技术，基于被毛、肌肉、肝脏、心脏及粪便等多种组织样本，并结合季节维度，对麋鹿的日粮组成开展了调查，并评估了植物营养组分与日粮组成之间的相关性。贝叶斯同位素分析结果显示：通过被毛与粪便样本估算的秋冬两季日粮以C3草本植物为主（占比均值为42.7%~57.2%）；而通过肌肉与肝脏样本估算的夏季日粮则以C3非禾本科草本植物为主（占比均值为30.9%~41.6%）。皮尔逊相关性检验表明，通过被毛与粪便样本反映的冬季日粮组成贡献度，与粗蛋白（r=0.666，P<0.01）及可溶性糖（r=0.695，P<0.01）存在极显著相关性。上述结果证实，粗蛋白与可溶性糖是影响麋鹿冬季食性选择的关键因子。在当前麋鹿再引入工作面临栖息地碎片化、湿地退化及人类活动干扰等诸多挑战的背景下，未来的研究应综合考量不同资源特性与时间动态，全面评估麋鹿在不同资源条件及季节变化下的食性选择机制。