捕食者不但可通过直接捕食控制猎物数量，还可通过捕食风险效应影响猎物行为和生理而间接影响其繁殖和种群动态，因此研究捕食风险效应对猎物野外种群动态的影响日益受到关注。普氏原羚是我国特有种，生活在青海湖周边受天敌捕食和人为胁迫严重影响的草原上，其种群数量在过去二十年虽有缓慢上升，但仍处濒危状态，探明其中原因是保护该物种的关键前提。本课题拟对二个面临不同人为和自然胁迫压力的普氏原羚亚种群进行比较研究，利用野外行为生态观察和实验室生理分析（应激激素浓度）相结合的方法，明晰捕食者对普氏原羚的直接捕食作用、及捕食和人为胁迫的捕食风险效应，检验捕食风险效应的两个假说（捕食应激假说和捕食者敏感取食假说），从生理和行为两个角度来阐释普氏原羚种群动态的影响因子和调控机理，加深对捕食者—被捕食者关系的理解；甄别不同分布小区普氏原羚种群所受的主要威胁，为制定有针对性的保护措施、恢复该濒危物种提供科学依据和指导。

Studies have shown that predators can regulate prey's population dynamics through not only direct predation, but also indirect predation risk effect which can influence the prey's behavioural and physiological responses. There have been increasing interests in studying predation risk effects on prey's population dynamics in recent years. Przewalski's gazelle is an endemic species to China which ranges freely on the grassland around Qinghai Lake area under both natural and anthropogenic threats. Its population size has increased slightly during the past 20 years due to great conservation efforts, but its total polulation size is still very small with a conservation status being classified as endangered species. Understanding the mechanisms and reasons for its population dynamics is critical for conservation of this species. This project will be conducted with subpopulations at two distribution areas with different conditions of natural and anthropogenic threats. A series of field data will be collected, inclduing population parameters of the gazelle and its main predator (wolf), behavioural data of the gazelle udner different environmental conditions, and fecal samples of both the gazelle and the predator. The contents of cortisol (the stress hormone) will be measured at the laboratory from the gazelle’s freshly-frozen fecal samples as an indicator of overall level of its response to stress from both predator and anthropogenic threats. The project will examine the direct predation effects on the gazelle from the wolves, and the indirect predation risk effects from both the wolves and the anthropogenic threats. Two hypotheses regarding predation risk effects, i.e., the predation stress hypothesis and the predator-sensitive foraging hypothesis, will be tested with the behavioural data, population dynamic data, and physiological data of the gazelle. We aim to elaborate the relationship between the gazelle’s population dynamics and the gazelle’s behavioural and physiological responses to both its predator and anthropogenic threats in order to better understand the mechanisms underlying the gazelle’s population dynamics in different areas. This study will also identify the main threats to the gazelle populations in different areas, which will be necessary for development and implementation of site-specific and scientific conservation measures and action plans for the gazelle. Thus, this study will have strong implications for both the theory on predator-prey interactions and conservation practice.