Landscape-level Population Dynamics of an Avian Habitat Specialist Invading an Alien Grassland in Southeastern Arizona

9815293博克由于干旱和过度放牧，波特里麻雀几乎从美国西南部消失。这种鸟，一个高草专家，现在通常被限制在低地地区的草地上。在这片可以长到2米高的天然草原上，这些鸟将它们的巢隐藏在这些高草的底部，然后在邻近的斜坡上觅食蚱蜢和其他昆虫。最近，这些鸟类开始在天然的高地草原地区筑巢，那里的草比高的scaton草矮，但蝗虫密度很高。此外，它们也在覆盖物主要是引进的非洲相思草的地区筑巢，那里的覆盖物几乎和本地的臭草一样重。然而，在这些地区，蝗虫相对稀少。这种独特的情况允许测试的假设和预测景观生态，汇/源和集合种群动态和外来植被的生态影响。这项研究将回答这样的问题：什么是草覆盖（安全的筑巢栖息地）与食物供应（高蚱蜢数量），以繁殖成功的Botteri麻雀的相对重要性？ 三个栖息地（萨卡顿，本土高地草原和外来草原）的综合贡献是什么？Botteri麻雀的区域种群动态，以及这些如何与整个物种的人口在其范围的北方边缘的汇/源状态？此外，它将解决是否异国情调的草地代表一个合适的栖息地的鸟类或引进的草地是一个生态陷阱，这个物种。

9815293BockThe Botteri's sparrow has almost disappeared from the American Southwest due to drought and overgrazing. This bird, a tallgrass specialist, is usually now restricted to stands of scaton grass in lowland areas. In this native grassland that can grow over 2 meters tall, the birds conceal their nests from predators at the bases of these tall grasses and then forage on adjacent slopes for grasshoppers and other insects. Recently, these birds have begun nesting in native upland grassland areas where the grasses are shorter than the tall stands of scaton grass, but grasshopper densities are high. In addition, they also nest in areas where the cover is dominated by introduced African lovegrass, where the cover is nearly as heavy as the native scaton. However, in these areas, grasshoppers are relatively scarce. This unique situation allows for testing of hypotheses and predictions of landscape ecology, sink/source and metapopulation dynamics and the ecological impacts of alien vegetation. This research will answer such questions as: What is the relative importance of grass cover (safe nesting habitat) versus food availability (high grasshopper numbers) to reproductive success in the Botteri sparrow? What are the combined contributions of the three habitats (sacaton, native upland grasslands and exotic grassland) to regional population dynamics of the Botteri sparrow and how these relate to the sink/source status of the entire species population at the northern margin of its range? In addition, it will address whether the exotic grasslands represent a suitable habitat for the birds or are the introduced grasslands an ecological trap for this species.