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知之甚少。 解释这种下降的一个主要假设是人类造成的栖息地转换和候鸟热带越冬地的丧失。 本研究的目的是评估在牙买加，西印度群岛的人类改造与自然栖息地的移民陆地鸟类的生态健康。 这个岛屿包括红树林和加勒比热带干旱森林，以及人类改造的柑橘和咖啡果园，放牧的第二次生长灌木丛和生态复杂的农村居民区。 在每个栖息地内，调查人员将量化（1）留鸟和候鸟的丰度，（2）选定的候鸟物种的越冬存活率，（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用性的季节性模式。 这些数据加上实验操作的资源丰度将使调查人员测试替代假设解释的生态基础，为个人和人口的反应，这些不同的栖息地。 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维持热带加勒比国家的生物资源最相容。 栖息地特定的土地利用对鸟类消费者和他们的食物资源的影响是迫切需要的生态健全和有效的野生动物保护建议的发展。

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.