<b>Abundance of human-made food contribute to higher tolerance of human approaches in black-headed gulls</b>

Food resources are key drivers of changes in animal behavior. The feeding relationships between humans and wildlife, intentionally or unintentionally, can be understood as a behavioral evolution that occurs as animals discover new ways of surviving in urban environments. This study was conducted in February 2024 in Haizhou Bay (34.933 N, 119.205 E), located in Haitou Town, Ganyu District, Lianyungang City, Jiangsu Province, along the central coast of China, bordering the Yellow Sea to the east.We focuses on the black-headed gull (<i>Chroicocephalus ridibundus</i>) to examine avian behavioral responses to human activities. We measured the flight initiation distance (FID) of black-headed gulls in three different areas (beach, shrimp ponds, and docks) in Haizhou Bay, Lianyungang, Jiangsu Province, China. The results showed that black-headed gulls in the dock area exhibited significantly shorter FIDs, suggesting a higher tolerance for human proximity. This tolerance is likely due to the incidental accumulation of oyster (family Ostreidae) shells by fishermen, which creates an association between humans and food resources, reducing their wariness of humans. In contrast, black-headed gulls in beach and shrimp pond areas, where such "quasi-feeding" phenomena are absent, display longer FIDs, indicating a higher level of vigilance toward humans. Our study suggests that food resources are essential in driving behavioral evolution in black-headed gulls. Also, this study highlights the importance of cognitive adaptation in animals' response to human activities, suggesting that behavioral flexibility is vital for animals to adapt to urbanization and respond effectively to human activities.食物资源是驱动动物行为改变的核心因素。人类与野生动物之间有意或无意形成的取食关联，可被视为动物在城市环境中探索新生存策略时所发生的行为演化过程。本研究于2024年2月在中国中部沿海的江苏省连云港市赣榆区海头镇海州湾（北纬34.933°，东经119.205°）开展，该区域东临黄海。本研究以红嘴鸥（*Chroicocephalus ridibundus*）为研究对象，探究鸟类对人类活动的行为响应。本研究测定了连云港市海州湾三处不同生境（滩涂、虾塘与码头）内红嘴鸥的起飞逃逸距离（Flight Initiation Distance，FID）。研究结果显示，码头生境中的红嘴鸥起飞逃逸距离显著更短，表明其对人类近距离接触的耐受度更高。该耐受特性或源于渔民偶然堆积的牡蛎（牡蛎科Ostreidae）壳，由此建立了人类与食物资源之间的关联，降低了红嘴鸥对人类的警戒心。与之相对，滩涂与虾塘生境中未出现此类“类取食”现象，红嘴鸥的起飞逃逸距离更长，显示其对人类的警戒水平更高。本研究表明，食物资源是驱动红嘴鸥行为演化的关键要素。此外，本研究强调了认知适应在动物响应人类活动过程中的重要性，指出行为灵活性是动物适应城市化并有效应对人类活动的核心前提。