Reasons for Migration
Birds that migrate are those that spend parts of the year in different areas according to what food is available and seasonal weather change. Some species only migrate a short distance in response to abrupt weather changes, but some migrate thousands of miles.
Most migratory bird species travel along a "flyway." In the Northern Hemisphere, this is generally south for the winter season and north in spring to breed and raise young.
Many larger bird species such as geese fly along their migration routes in flocks to help reduce individual stress and save energy by flying in formations that decrease wind resistance, such as the V-formation.
According to the Forest Service, more than 300 of the 850 bird species in North America spend the summer in the United States, and winter in Mexico and South America.
Some birds such as the red-breasted nuthatch are considered irruptive migrants, meaning the number that migrate and the winter range varies greatly each year. In this case, the Eastern year-round range is expanding southward.
Article Written By Naomi Judd
Naomi M. Judd is a naturalist, artist and writer. Her work has been published in various literary journals, newspapers and websites. Judd holds a self-designed Bachelor of Arts in adventure writing from Plymouth State University and is earning a Master of Fine Arts in creative writing from the University of Southern Maine.