鸟类繁殖中，备选繁殖策略经常被采用，包括繁殖延迟、繁殖合作、婚外交配和离婚。这些备选策略能显著影响个体单次繁殖的产出，但对其终身繁殖成功的影响还缺少足够证据。本项目基于长期个体标记和监测的数据，在合作繁殖的鸟类——灰喜鹊中，研究四种备选策略对个体终身繁殖成功的影响。通过追溯帮助者的来源和身份、比较帮助者与其同巢同胞的繁殖表现，分析繁殖延迟能够提高个体的终身繁殖成功。通过分析合作群内的优势繁殖者如何权衡招募帮助者的利益和代价，解释繁殖合作策略与环境因子的关系。通过比较婚外交配策略者当年繁殖成功和来年的繁殖表现，检测婚外交配对繁殖产出的短期和长期效应。通过分析个体繁殖表现随年龄增长的变化趋势、比较个体离婚前、后的配对年龄结构来检验离婚策略是否存在年龄效应。在研究过程中，我们将通过人工递食实验、天敌模拟实验、以及表型修饰等方法来调控个体及领域质量，分析备选繁殖策略如何对生态因子的波动做出回应。

Alternative breeding strategies, including delayed reproduction, cooperative breeding, extra-pair copulations and divorce, have been frequently adopted by breeders of birds. Though it has been widely accepted that those alternative strategies can influence the output of current reproduction, we know less about their effects on the lifetime reproductive success (LRS) of birds. In this project, we will explore how these four alternative strategies influence the LRS of a cooperatively-breeding corvid, the azure-winged magpie Cyanopica cyana, based on a long-term data about individual banding and monitoring. Through tracing the origin and identity of helpers within cooperative groups, we can compare the breeding performance of helpers and their nest-mates to examine whether delayed reproduction has a positive effect on the LRS of helpers. By investigating how the dominant pair of cooperative group balances the benefits and costs of enlisting extra individuals as helpers, we can illustrate how cooperative breeding may occur under special environmental conditions. In order to find out both short- and long-term effects of engaging in extra-pair copulations on the reproduction, we need to compare the current reproductive success of a cuckolding individual with its breeding performance in subsequent season. Finally, we want to prove that there is an aging effect on the divorce decision by two means. One is to analyze the tendency of an individual’s breeding performance with aging; the other is to determine the age of intact and new social mates of a divorced breeder. Over the course of the project, we will design some experiments, such as artificial feeding, predator introduction and modification of phenotypic traits, to adjust the quality of both individual breeder and territory. Then, we may know how an individual makes response to the dynamics of ecological factors by changing its alternative breeding strategy.