Collaborative Research: Population Responses of Neotropical-Nearctic Migrant Birds to Human-Impacted Habitats in the Winter Grounds

候鸟数量下降的具体原因尚不清楚。解释这种下降的一个主要假设是，候鸟在热带越冬地的栖息地被人为改变和丧失。这项研究的目的是评估西印度群岛牙买加人工改造和自然栖息地候鸟的生态健康。该岛包括红树林和加勒比海热带干燥森林，以及人工改造的柑橘和咖啡园、放牧的次生灌木丛和生态复杂的农村居民区。在每个栖息地内，研究人员将量化(1)留鸟和候鸟的丰度，(2)选定候鸟的越冬存活，(3)选定物种的鸟类状况指标，以及(4)能够支持观察到的鸟类种群的食物资源可获得性的季节模式。这些数据再加上对资源丰度的实验操作，将使研究人员能够测试解释个体和种群对这些不同栖息地反应的生态学基础的替代假说。这项研究的结果将立即适用于动物种群的保护，指出哪些人类活动与热带加勒比国家的生物资源维护最相容。针对特定栖息地的土地利用对鸟类消费者及其食物资源的影响，对于制定生态健全和有效的野生动物保护建议是至关重要的。

The specific causes of population declines of migratory birds are poorly understood. A major hypothesis to explain the declines is human-caused habitat conversion and loss in the tropical wintering grounds of the migratory birds. The objective of this research is to assess the ecological health of migrant land birds in human-modified versus natural habitats in Jamaica, West Indies. This island includes mangroves and Caribbean tropical dry forest, and human-modified habitats of citrus and coffee orchards, grazed second-growth scrub, and the ecologically complex rural residential areas. Within each habitat the investigators will quantify (1) abundance of resident and migratory birds, (2) overwinter survival of selected migratory species, (3) indicators of bird condition for the selected species, and (4) seasonal patterns of food resource availability capable of supporting the observed bird populations. These data coupled with experimental manipulations of resource abundance will allow the investigators to test alternative hypotheses explaining the ecological bases for the individual and population responses to these different habitats. The results of this research will be immediately applicable to conservation of animal populations by indicating which human activities are most compatible with maintenance of biotic resources in tropical Caribbean countries. The effects of habitat-specific land-use on avian consumers and their food resources is critically needed for the development of ecologically sound and effective wildlife-conservation recommendations.