When migrating birds and other creatures move along a path of plant communities in bloom, they follow what has come to be known as a nectar trail. Should any of these plants be eliminated from the sequence—whether through habitat destruction, pests, or even aberrant weather—the movement of these pollinators may be interrupted and their very survival threatened. In recent efforts by ecologists and activists to envision a continental-scale network of protected areas connected by wildlife corridors, the peculiar roles of migratory pollinators which travel the entire length of this network cannot be underestimated in shaping the ultimate conservation design. This book, a unique work of comparative zoogeography and conservation biology, is the first to bring together studies of these important migratory pollinators and of what we must do to conserve them. It considers the similarities and differences among the behavior and habitat requirements of several species of migratory pollinators and seed dispersers in the West—primarily rufous hummingbirds, white-winged doves, lesser long-nosed bats, and monarch butterflies. It examines the population dynamics of these four species in flyways that extend from the Pacific Ocean to the continental backbone of the Sierra Madre Oriental and Rocky Mountains, and it investigates their foraging and roosting behaviors as they journey from the Tropic of Cancer in western Mexico into the deserts, grasslands, and thornscrub of the U.S.-Mexico borderlands. The four pollinators whose journeys are traced here differ dramatically from one another in foraging strategies and stopover fidelities, but all challenge many of the truisms that have emerged regarding the status of migratory species in general. The rufous hummingbird makes the longest known avian migration in relation to body size and is a key to identifying nectar corridors running through northwestern Mexico to the United States. And there is new evidence to challenge the long-supposed separation of eastern and western monarch butterfly populations by the Rocky Mountains as these insects migrate. Conserving Migratory Pollinators and Nectar Corridors in Western North America demonstrates new efforts to understand migratory species and to determine whether their densities, survival rates, and health are changing in response to changes in the distribution and abundance of nectar plants found within their ranges. Representing collaborative efforts that bridge field ecology and conservation biology in both theory and practice, it is dedicated to safeguarding dynamic interactions among plants and pollinators that are only now being identified.