Follow the paths of a hundred species of bird as they travel on their migratory routes from their breeding grounds in North America to their wintering ranges in Central and South America and back. Each dot on the map represents the average location of each bird species at the designated time of year. These data were generated by the Cornell Lab of Ornithology with the help of everyday accounts of people submitting their own bird sightings. This approach allowed the scientists to obtain many more records of these birds' average locations throughout the year.