Stephen Mirick | Guest Contributor
As the days grow shorter and the nights get cooler, many birds throughout easternCanada and northeastern New England migrate south through New Hampshire heading for wintering areas that stretch from the southern United States down to Central and South America. While we often refer to this as “fall” migration, the migration period starts for many birds during the summer as early as the first week of July, and extends through the fall and into the early winter.
Migration in birds is extremely complex and varies between the different species. For many birds, the actual flight southward goes almost unnoticed as they migrate overhead at night! Driven by an innate urge, and following celestial compasses, small land birds such as warblers, vireos, orioles, flycatchers and sparrows form loose flocks and depart on clear evenings following cold fronts; riding the northwest tail winds that carry them southward. Many of these birds follow the coastline and transients can often be found along the trails at Odiorne Point State Park during September and October. They feed on fruit and insects, as they try to gain enough weight and energy to finish their migration south. For some species like the chickadee-sized Blackpoll Warbler, this may require long flights taking them over the open ocean to South America. These non-stop flights can last up to 4 straight days and are part of an overall round-trip journey of up to 12,400 miles!
Many species of birds also migrate during the day and their migration is much more easily observed. Along the coast, one of the most spectacular migrations takes place with the Double-crested Cormorants which are heading to the southeastern United States to spend the winter. From September through October, large skeins of cormorants fly south along the shoreline in flocks numbering from 50 to 500 or more. They follow the contours of the coast and fly in broken formations similar to the neat V-shaped flocks formed by their distant cousin the Canada Goose. Canada Geese also migrate down the coastline, but generally leave a bit later than the Cormorants; usually peaking from October through December.
The rare Piping Plovers that nest on the beaches in Hampton and Seabrook leave by the end of August and migrate only a short distance to the southeastern United States and the Caribbean. But many other types of sandpipers and plovers migrate a much longer distance; some flying from their breeding grounds on the Arctic tundra and migrating as far south as Tierra del Fuego at the tip of South America! The numbers peak in late August, but continue throughout the fall. They often gather in mixed species flocks along the beaches or in the mudflats or seaweed along the shoreline at high tide.