Research into terrestrial bird population declines has often focused on fragmentation of forest habitats and conversion of habitats for agricultural or urban land uses. The causes of population declines of riparian birds (those associated with stream-side vegetation) are likely to be different and varied, but land uses resulting in sedimentation, acidification, and degradation of aquatic insect communities may be critical to the conservation of these bird species. We are studying the ecology of the Louisiana Waterthrush on the breeding and wintering grounds, identifying landscape-level factors, territory characteristics, and specific stream quality measures associated with reproductive success and over-winter survival, and assessing the use of birds as indicators of water quality and ecosystem health. We are also assessing the connectivity of wintering populations to breeding populations through isotopic markers, and providing the basis for studies of carryover effects of habitat conditions.