The Common Tern is the most widespread and familiar North American tern, known also for its attractive plumage and graceful flight, and for its long history as a symbol of the conservation movement. It was widely sought after in the late nineteenth century for the millinery trade, in which feathers, wings, or entire stuffed terns were mounted on fashionable women's hats. Slaughter of terns and other seabirds for this purpose peaked in the 1870s and 1880s, and by the end of the century this species was almost extirpated from the Atlantic Coast and from many inland areas.
Together with the simultaneous slaughter of herons and other birds, this was the impetus for the formation of the Audubon societies and for other conservation initiatives. These were initially focused on protecting remnant colonies, but culminated in 1918 with the passage of comprehensive bird protection legislation implementing the Migratory Bird Treaty between the U.S. and Canada. The Common Tern recovered remarkably quickly, and by the 1930s had reoccupied most of its original range and recovered much of its original numbers. In the middle of the twentieth century, however, numbers began to decline again as burgeoning gull populations took over many of the best breeding sites, and toxic chemicals reduced breeding success in many areas. Since 1970, the Common Tern and other waterbirds that nest on the same islands with it have become the targets of more diffuse and varied conservation efforts. These have included regulation and control of releases of toxic chemicals, management of dumps and other sources of food for gulls, protection of breeding sites against human disturbance and development, control of specialist predators, and restoration of former sites by removing gulls. Breeding populations increased again in several areas during the last quarter of the twentieth century. However, numbers are still well below historical highs, and even maintaining them at present levels requires continuous management at many sites.
The Common Tern readily habituates to the presence and activity of biologists and has been the subject of many intensive studies. In addition to descriptive studies of behavior, foraging, diet, breeding biology, and molt, it has been used for many detailed studies of behavior, ecology, physiology, growth, energetics, contaminants, and toxicology. More than one million Common Terns have been banded in North America, forming the basis for many studies of migration, dispersal, demography, age-related biology, and senescence. Extensive studies in Europe and Asia have been summarized in three major handbook articles ( Glutz Von Blotzheim and Bauer 1982 , Cramp 1985a , Il'Icev and Zubakin 1990 ); another handbook article ( Higgins and Davies 1996 ) summarizes information from the Pacific and Australasian regions. Two recent books have been devoted exclusively to Common Terns: Burger and Gochfeld 1991e on social behavior and Hume 1993 on natural history, as well as a special symposium on the species in western Europe ( Becker and Sudmann 1998 ). Several other books have presented comparative data on other terns or related seabirds ( Bickerton 1912 , Marples and Marples 1934 , Burger and Gochfeld 1990b , Olsen and Larsson 1995 ).
In this account, citations to named individuals refer to unpublished data supplied as personal communications; the author's unpublished data are cited as (ICTN).