LTREB: Role of winter sociality in the evolution of facultative social behavior

提案题目：冬季社会性在兼性社会行为进化中的作用这是一项继续对一种有彩色条纹的西部蓝鸟进行长期研究的提案，这种蓝鸟的儿子表现出显著的行为可塑性，表现为与父母一起过冬，独立繁殖，帮助父母筑巢，并在丧偶的雌性巢穴中觅食。这项研究的具体目的是确定在第一个冬天留在父母领地的年轻雄性的利益，这种行为是以后与父母进一步互动的必要前提。槲寄生浆果是一种稳定的冬季资源，是该系统全年领土行为的关键。一项实验包括从冬季领地移走一半的槲寄生，以确定槲寄生数量对后代是否留下来、它们的生存状况、以及它们能否成功获得配偶和自己的繁殖领地的影响。另一种假设是，儿子呆在家里是因为他们和父母在一起时得到了优待，这一假设也将得到检验。事实上，父母资源的获取和父母的优待可能同时解释了为什么儿子留在家里。这项工作是新颖的，因为槲寄生是一种独特的可操纵的食物资源，它只在冬季可用，这使得在一个全年都有领地的物种中，冬季食物对分散和家庭稳定的重要性完全分离。虽然这项研究的结果将解决进化行为生态学中的一个基本问题，但它们也将解决加利福尼亚西部蓝鸟数量下降的潜在重要性问题。如果槲寄生的数量被证明对年轻雄性在冬季呆在家里的倾向至关重要，而槲寄生的减少对呆在家里的儿子的条件和生存有负面影响，那么我们将确定一个关键的环境变量来调节加州的蓝鸟种群。

PI: Janis L. Dickinson Proposal # 0097027Proposal Title: The role of winter sociality in the evolution of facultative social behaviorThis is a proposal to continue a long-term study of a color-banded population of western bluebirds whose sons exhibit remarkable behavioral plasticity in the form of staying with parents for winter, breeding on their own, helping at their parents' nest, and feeding at nests of widowed females. The specific aim of this study is to determine the benefits for young males remaining on their parents' territory through the first winter, a behavior that is a necessary precondition for further interaction with parents later in life. Mistletoe berries are a stable winter resource that is key to year-round territorial behavior in this system. An experiment that involves removing half the mistletoe from winter territories will determine the impact of mistletoe abundance on whether sons stay, their condition, and their success at acquiring a mate and breeding territory of their own. The alternative hypothesis, that sons benefit by staying home due to the preferential treatment they receive when they remain with parents, will also be tested. In fact, both access to parental resources and preferential treatment by parents may simultaneously explain why sons remain home. This work is novel because mistletoe is a uniquely manipulable food resource and its availability only during winter allows for a clean separation of the importance of winter food for dispersal and family stability in a species with year-round territories. Although the results of this study will address a basic question in evolutionary behavioral ecology, they will also address an issue of potential importance to the decline of western bluebirds in California. If mistletoe quantity proves critical to the tendency for young males to stay home for winter and reduction of mistletoe has negative impacts on the condition and survival of stay-at-home sons, then we will have identified a key environmental variable regulating bluebird populations in California.