Seasonal carry-over effects and connectivity inmigratory songbirds

每年秋天，数十亿只鸣禽在温带和热带地区之间迁徙，但人们对繁殖或越冬事件如何影响迁徙的时间和速度知之甚少，反之亦然，也不知道迁徙策略中个体差异的适应性后果。我开创了在候鸟身上使用轻型地理定位器的先河。地理定位器是档案标签（< 1.5g），当迁移后检索时，可以用来推断迁移路线和时间。自2007年以来，我一直使用地理定位器对画眉鸟和紫马丁进行定位，并记录了在同一种群中繁殖的个体在迁徙路线、时间和速度方面的广泛差异。我将使用这一创新技术来测试(1)繁殖努力和时间如何影响秋季迁徙、换毛迁移重叠和随后的生存；(2)到达日期如何影响冬季领地质量、生存、冬季身体状况和随后的春季迁徙；(3)繁殖地和越冬地之间的连通性模式如何与种群下降联系在一起。为了观察携带效应，将对窝卵数量和繁殖时间进行控制，以检验高亲代努力延迟迁徙的预测。我还会操纵寄生虫的负荷来检验被变形血寄生虫感染会减缓秋季迁徙的预测。我将在越冬鸣禽身上部署地理定位器，以测试秋季迁徙策略如何影响随后的领地质量、所有权和越冬生存。冬季领地质量的实验操作（“升级”到更好的领地，补充食物）将检验质量差的领地推迟春季迁徙从而推迟到达繁殖领地的预测。预测连通性模式会影响繁殖地种群数量的下降，因为分散的连通性会将一个地区冬季存活率低的影响扩散到大量繁殖种群。将在多个繁殖种群和越冬种群上部署地理定位器，绘制连通性模式，并测试连通性强度是否能预测区域繁殖种群趋势。

Each fall billions of songbirds migrate between the temperate zone and tropics but little is known about how breeding or wintering events affect the timing and pace of migration, and vice versa, or the fitness consequences of individual differences in migration strategy. I have pioneered the use of light level geolocators on migratory songbirds. Geolocators are archival tags (< 1.5g) that when retrieved after migration can be used to infer migration routes and timing. I have used geolocators on Wood Thrush and Purple Martins since 2007 and have documented extensive variation in migration route, timing, and speed for individuals breeding in the same population. I will use this innovative technology to test (1) how reproductive effort and timing affects fall migration, moult-migration overlap and subsequent survival, (2) how arrival date affects winter territory quality, survival, winter body condition and subsequent spring migration, and (3) how connectivity patterns between breeding and wintering sites are linked to population declines. To look at carry-over effects, clutch size and timing of breeding will be manipulated to test the prediction that high parental effort delays migration. I will also manipulate parasite loads to test the prediction that infection by Haemoproteus blood parasites slows fall migration. I will deploy geolocators on wintering songbirds to test how fall migration strategy affects subsequent territory quality, ownership, and over-winter survival. Experimental manipulation of winter territory quality ("upgrading" to a better territory, food supplementation) will test the prediction that poor quality territory delays spring migration and thus arrival on the breeding territory. Connectivity patterns are predicted to affect population decline on the breeding grounds because diffuse connectivity spreads the impact of low winter survival in a region over a large number of breeding populations. Geolocators will be deployed on multiple breeding and wintering populations of Wood Thrushes and Purple Martins to map connectivity patterns and test if the strength of connectivity predicts regional breeding population trends.