An excerpt from the Introduction;
North American warblers, or wood-warblers, have long-captivated birders with their diversity, bright plumages, sprightly behavior, and spectacular migrations. They have also been the subject of considerable scientific investigation, including pioneering studies of migration strategies, behavior, population and community ecology, niche separation, habit associations, and human-induced population declines. At the same time, these warblers have presented a challenge for field identification for several reasons. First, some plumages of related species are very similar, particularly of females and immature birds. Second, warblers are small and very active, often foraging at high levels and in dense foliage, where subtle markings are hard to discern. Third, genearl field guides have simply pointed out the confusing nature of many warbler plumages, especially in the fall, without attempting to throughly treat identifying characters. In this volume we bring together considerably more information on plumages, vocalizations, behavior, habitats, and distribution of warblers than can be accommodated in a standard field guide to birds. It is our conviction that details of distribution, migration patterns, and habitats, along with discussions of appearance, voice, and behavior, will provide the reader with a better framework for working through difficult identifications and understanding the significance of particular sightings.