Migratory birds are part of a global system that developed over thousands of years. Birds play important roles in maintaining ecosystems by keeping populations of insects and other prey in balance, spreading seeds, and providing food for predators. Habitat loss is the greatest problem facing Neotropical migratory songbirds and other wildlife. Many species construct open cup nests. These nests are vulnerable to blue jays, raccoons, house cats, and other predators.
Songbirds often nest only once during each breeding season.
Riparian habitats are found on the dges of water courses, such as streams, rivers, and lakes. These habitats are vital in supporting plant and animal life. In the dry climate of the western US, riparian habitat is especially critical for nesting songbirds. The birds use the vegetation for nesting and feeding. Large populations of insects thrive in riparian areas because of the dense and varied vegetation.