Spring is not yet upon us but subtle shifts are already in the air. The light is changing and with it, many birds who vacated the city during the winter months are beginning to return.
In February, large flocks of American Robins appeared in the area and began gathering in Rock Creek Park, picking through leaf litter, and eating whatever insects, berries, and seeds they found. They are among the first bird species to migrate. Not all American Robins migrate. In fact, some species, such as the Northern Cardinal and Northwestern Crow, do not migrate at all.
So What Is Migration Anyway?
Migration is an annual large scale movement of birds between their summer and winter homes. Unlike humans, who have access to uninterrupted sources of food and shelter year round, birds must migrate when food grows scarce. In general, this means following the light and moving to warmer climates where there is an abundance of plant and insect life.
Key Facts To Know About Migration:
- To date, scientists have recorded over 650 species of birds that, nest, breed, and raise their young in North America.
- Migration distance varies. Some species travel only short distances; others may cover distances that span the width of several states.
- Many species–such as raptors, vultures, waterfowl, thrushes, warblers, and other songbirds–undertake migratory journeys that cover thousands of miles and can take weeks to complete.
- Cool Fact: The Arctic Tern has one of the longest migrations on record. Each year, Arctic Terns travel as much as 24,000 miles (round trip) from their winter home in Antarctic to their breeding grounds in far northern Canada and back again. Since Arctic Terns can live to be at least 34 years, one bird may fly more than 800,000 miles in its lifetime!
Did You Know Birds Return to the Same Nesting Ground Every Year?
Birds of a feather really do flock together! Each migratory species has its own route to and from its nesting ground and winter home. These paths are often very broad (spanning many miles) but, individual birds are surprisingly loyal to to their nesting locations. Each year, newborn birds take flight and begin what is often a long and arduous journey to a winter home they have never before seen and, the following spring, return to the place they were born.
Developments in technology have improved scientists ability to track and study birds but the secret to their incredible navigational skills is still largely unknown. It is likely that they use many techniques such as smell, sensing changes in the earth’s magnetic field, and navigating by the star.
Although most birds like to migrate in the company of members of their own species, they often do so while traveling within larger mixed flocks.
Interested in learning more? Stay tuned for Part 2 to learn about the threats migratory birds face and how you can help.