本研究聚焦华龙洞3种熊科动物——巴氏大熊猫(Ailuropoda melanoleuca baconi)、亚洲黑熊(Ursus thibetanus)和棕熊(Ursus arctos)的摄食生态，探讨共生熊类的生态位差异及变化。通过牙釉质碳氧稳定同位素分析，发现第1地点棕熊栖息于半开阔林地，大熊猫与黑熊则占据密闭森林，黑熊的食性更为多样化；第3地点棕熊消失，大熊猫与黑熊依然占据密林，但黑熊的摄食行为可能有所变化。区域对比显示，中晚更新世巴氏大熊猫与亚洲黑熊在广西和安徽地区均以密林为核心生境，但二者普遍存在生态位差异。通过对更新世大熊猫的数据进行整合分析，我们发现从早更新世的小种大熊猫和武陵山大熊猫，到中晚更新世的巴氏大熊猫，其碳氧同位素数据均呈现出时空差异。这些差异不仅反映了不同种类大熊猫的古生态特征，也与中国南方地区更新世气候环境的区域性差异密切相关。本研究首次聚焦于更新世共生熊科动物的稳定同位素古生态，为理解南方古人类与动物协同演化提供生态背景。

This study investigates the dietary ecology of three sympatric Ursidae species— Ailuropoda melanoleuca baconi, Ursus thibetanus, and Ursus arctos — from two sites at Hualonglong (locality 1: ~300 ka; locality 3: late Middle Pleistocene to Late Pleistocene) in Anhui Province, southern China. Through stable carbon and oxygen isotope (δ¹³C, δ¹⁸O) analysis of tooth enamel, this study reveals distinct ecological strategies: at locality 1, U. arctos (n=3) occupied intermediate woodlands (δ¹³C_diet= −23.1‰±1.9‰), while A. melanoleuca baconi (n=5) and U. thibetanus (n=4) inhibited close-canopy forests (δ¹³C_diet values are −27.8‰±0.6‰ and −27.8‰±0.8‰, respectively). The latter exhibites more diverse dietary ecology, as reflected by their varied δ¹⁸O values (−6.9‰±0.3‰ and −8.3‰±1.1‰). By locality 3, U. arctos were absent, but A. melanoleuca baconi (n=5) and U. thibetanus (n=5) continue to inhabit close-canopy forests. The δ¹⁸O convergence between A. melanoleuca baconi (−7.0‰±0.4‰) and U. thibetanus (−7.2‰±0.8‰) suggests possible ecological shifts in U. thibetanus. Regional comparisons (Guangxi: Baxian Cave, Quzai Cave, and Yugong Cave from previous studies; Anhui: two localities at Hualongdong in this study) indicate that during the middle-late Pleistocene, both A. melanoleuca baconi (δ¹³C_diet values were −27.1‰±1.0‰ (n=20) in Guangxi and −27.8‰±0.6‰ (n=10) in Anhui) and U. thibetanus (δ¹³C_diet values were −27.7‰±1.7‰ (n=10) in Guangxi and −27.8‰±0.6‰ (n=9) in Anhui) consistently exploited close-canopy forests in Guangxi and Anhui, yet maintained niche partitioning at each sites. By integrating isotopic data from Pleistocene Ailuropoda, we observed a gradual shift towards more positive δ¹³C_diet values from the Early Pleistocene Ailuropoda microta (data from Gigantopithecus Cave and Yanliang Cave in Guangxi, δ¹³C_diet= −28.2‰±1.0‰, n=8) and A. melanoleuca wulingshanensis (data from Longgu Cave in Hubei, δ¹³C_diet= −27.7‰±0.7‰, n=4) to the middle-late Pleistocene A. melanoleuca baconi (all aforementioned specimens from Guangxi and Anhui, δ¹³C_diet= −27.3‰ ±0.9‰, n=30). Their δ¹⁸O values also varied by regions and periods. The spatiotemporal isotopic differences in Pleistocene Ailuropoda, linked to their specialized bamboo-diet, underscore the differences in regional paleoenvironments in southern China. In Guangxi, A. melanoleuca baconi exhibited slightly higher δ¹³C_diet values and a broader range of δ¹⁸O values compared to A. microta. This may suggest that, with the increase in body mass and food intake, A. melanoleuca baconi occupied more open habitats and utilized bamboo more diversely, as potentially evidenced by a wider variety of bamboo species, parts, and distribution ranges. This study provides the first isotopic evidence for sympatric Ursidae niche partitioning in southern China, offering critical paleoenvironmental context for understanding the coevolution between human and non-human animals in this region.