If you still need to checkoff the Least, or Roseate, terns from your birding life list, or simply like to watch birds, you might consider visiting Cape Cod National Seashore as those species are staging there in advance of their migration south.

The importance of the seashore's beaches to nesting piping plovers and least terns is well known to most Cape residents and visitors. However, the importance of outer-Cape beaches to Common, Least, and Roseate terns and other shorebirds before and during migration may be less widely appreciated, said Dr. Jason Taylor, the seashore's chief of natural resource management.

Even while some least terns and piping plovers are raising chicks on seashore beaches, roseate and common terns are beginning to gather, particularly on the barrier beaches that form Hatches Harbor, Jeremy Point, and Coast Guard/Nauset, he said in a release.

"Terns, sometimes referred to as 'sea swallows,' are smaller than gulls and more graceful flyers, with forked tails and slender wings. After the nesting season, adult and fledgling terns disperse from their breeding grounds to 'stage' on beaches and flats in southern New England before their 4,500-mile migration to South America," said Chief Taylor.

During this staging period, the ecologist said "the terns rest and feed so they can build body mass and fat reserves necessary to fuel their long migration south. This is a critical period for these terns and other staging and migrating shorebirds; it is important that disturbances to these birds while resting on beaches and flats are minimized."

Visitors to Cape Cod National Seashore are encouraged to enjoy terns and other shorebirds from a distance. That's because vehicles, boat landings, kayaks, dogs, and pedestrians can flush staging birds, interrupting feeding and resting and forcing them to expend energy they are trying to preserve for migration.

Over the years, Cape Cod National Seashore staff has assisted the Massachusetts Audubon Coastal Waterbird Program and the U.S. Geological Survey in documenting the importance of seashore beaches to terns about to embark on their fall migration. From July through mid-September, researchers have counted many thousands of terns congregating at Hatches Harbor, Race Point, Coast Guard/Nauset Marsh, North Beach and South Beach/Monomoy beaches.

Most terns observed are common terns, a Species of Special Concern in Massachusetts, and roseate terns, listed as endangered by the State and the U.S. Fish and Wildlife Service. Based on counts of color-banded roseate terns, researchers estimate that 75 percent, or more, of the entire Northwest Atlantic Coast breeding population of roseate terns use Cape Cod National Seashore beaches and mudflats during their migration. A more detailed three-year study on the importance of the seashore to staging roseate terns is planned to begin in 2014.

Cape Cod National Seashore Superintendent George Price "encourages visitors and residents to observe this amazing phenomenon of thousands of birds utilizing national seashore beaches in preparation for their migration. It is important for people to witness this wonder of nature and share their experience with family and friends. Visitors are encouraged to enjoy terns and other shorebirds from a distance, but should avoid disturbing these staging birds, since this period of resting is critical to their survival."