Roseate Tern

The Roseate Tern is widespread in tropical and subtropical oceans, and a relatively small portion of its global population occurs in the North Atlantic. Most of these are in Europe and the Azores, leaving the northeastern United states with fewer than 5000 pairs, almost all of which are south of Cape Cod. Small numbers nested at the Isles of Shoals until roughly 1950, but the first modern breeding record came in 2001 when a pair settled in the restored Common Tern colony at the Isles of Shoals. This population is now consistently over 100 pairs, making it the largest number in the Gulf of Maine. It can still be hard to pick one out from the swirling masses of terns around the nesting colony.

Although they look superficially like Common Terns, Roseates have several distinguishing features during the breeding season. One of these is their all-black bill, sometimes with a little red at the base. They are also paler gray, with very little dark in the wings, and have a longer, all-white tail. They also nest in different habitats, preferring sheltered areas among rocks or under vegetation, and have even taken to using man-made wooden shelters in some colonies. Roseate Terns are less aggressive and rely on Common Terns for most of the colony’s defense. For this reason, the Roseate is not known to occur without its more boisterous relative anywhere in the North Atlantic.

After fledging in late July, juvenile Roseate Terns and their parents work their way to Cape Before Roseate Terns leave New England in early September, they congregate at a major staging area off Cape Cod. Birds will start arriving here shortly after fledging in late July, join birds from elsewhere in the Northeast, and depart south by early September. They spend the winter primarily off eastern Brazil. For a long time the location of the main wintering area was unknown. Early recoveries of banded birds provided the first clues, and subsequent use of small tracking devices allowed biologists to better identify where birds were concentrated.