Fitness Consequences of Avian Coloniality

9613638布朗这个项目试图了解动物为什么群居。许多不同的生物，包括人类，表现出不同程度的群体生活：一些动物成群结队或独自生活，而同一种群中的其他动物可能居住在巨大的群体中。要理解为什么有些人喜欢大群体生活，而另一些人喜欢小群体生活，就需要知道这种选择的生殖后果。某些动物如何从一种大小的群体中受益，而其他动物显然从另一种大小的群体中受益？这个问题在这项研究中得到了解决，该研究的重点是一种在北美西部大部分地区的陡峭的悬崖和峡谷边以及桥梁和建筑物的屋檐下繁殖的悬崖燕子(Hirundo Pyrhonota)。目标是确定不同鸟类如何在不同大小的巢中进行分类，以及基于什么；是否存在对所有鸟类最好的单一群体大小(繁殖成功最大的地方)；燕子对特定大小巢穴的偏好是否基于遗传，从而从其父母那里遗传；以及如果鸟巢大小发生变化，鸟类的筑巢成功将如何受到影响。这项研究主要使用标记-重新捕获方法，涉及鸟类环志：鸟类在特定地点环志，随后的活动和寿命通过在该地点或其他地点重新捕获它们来确定。这项研究建立在过去15年对这种悬崖燕子种群的研究基础上。这个项目将进一步加深我们对动物群体大小在自然界中为什么不同的理解。群体规模影响动物行为的许多方面：例如，疾病的传播、对食物等资源的竞争程度、交配策略的类型以及个体之间的合作和利他主义程度都受到社会群体规模的很大影响。如果我们首先知道是什么导致群体的大小不同，如果我们知道不同的群体是否由不同类型的个人组成，我们就能更好地理解群体生活的这些重要后果。悬崖燕子提供了一个经过充分研究的动物模型，其社会行为与其他社会物种相似，它将有助于洞察许多种类生物中支配群体形成的基本过程。

9613638 BROWN This project seeks to understand why animals live in groups. Many different organisms, including humans, show different degrees of group-living: some animals live in tiny groups or solitarily, whereas others in the same population may reside in enormous colonies. To understand why some individuals prefer living in large groups and others in small groups requires knowing the reproductive consequences of such choices. In what way do certain animals benefit from groups of one size while others apparently benefit from groups of another size? This question is addressed in this research, which focuses on a colonially breeding bird, the cliff swallow (_Hirundo pyrrhonota_), that breeds on the sides of steep cliffs and canyons and underneath the eaves of bridges and buildings throughout much of western North America. The objectives are to determine how different birds sort themselves among different sized nesting colonies and on what basis; whether there is a single colony size that is best for all birds (where reproductive success is greatest); whether a swallow's preference for a particular sized nesting colony is genetically based and thus inherited from its parents; and how the birds' nesting success is affected if their nesting colony is changed in size. The research uses primarily mark-recapture methods that involve bird banding: birds are banded at a particular site and their subsequent activity and lifespan is determined by recatching them at that site or others in later years. This study builds on 15 years of past work on this cliff swallow population. This project will further our understanding of why animal group sizes vary in nature. Group size affects many aspects of animal behavior: for example, the spread of disease, extent of competition for resources such as food, type of mating strategy, and extent of cooperation and altruism among individuals are all influenced heavily by the size of a social group. We can better understand these important conseque nces of group life if we know what causes groups to vary in size in the first place and if we know whether different groups are composed of different kinds of individuals. The cliff swallow provides a well-studied animal model whose social behavior parallels that of other social species, and it will yield insight into fundamental processes that govern group formation in many kinds of organisms.