Hundreds of species of birds can be seen on the Merrimack. During the spring and fall migrations, thousands of land and water birds move through The River Cities. During spring and summer, large numbers of herons, egrets and other birds nest and feed in the extensive salt marshes.
Each winter, bald eagles come to the Merrimack River. Nesting pairs remain throughout the year to raise their young. Deer Island in Amesbury is one of the ideal spots for viewing eagles.