Going, going, gone: is animal migration disappearing

Most of the migrants are in little immediate danger of extinction; rather, they are becoming less and less common. [...]birdwatchers can still see all of the species of migratory songbirds they seek each spring; they simply have to work harder to do so. There may be a few places along its migratory route where numbers of cerulean warblers can be found, but the majority of birds probably move in a rather diffuse wave between the two continents. [...]it is unrealistic to imagine that any discrete set of migratory reserves will work for this species.