The work offers a comprehensive, accessible review of avian migration, outlining its history and the biological and environmental factors that drive seasonal movements. It surveys observational and technological methods used to study migration, including banding, radio and radar tracking, laboratory experiments, and physiological research, and examines orientation and navigation mechanisms. Timing, speed, altitude, and patterns such as flyways, loops, and leap-frogging are described, along with segregation by age, sex, and species. The text discusses weather, topography, hazards, routes across regions, and theories on the origin and evolution of migratory behavior, concluding with an extensive bibliography.