Common Tern

IDENTIFICATION: A white tern with a long, forked tail, black cap, and red legs. The bill is red with a black tip, the amount of red decreasing after the breeding season. Lacks the pink tinge to the body feathers of the breeding plumage Roseate Tern. The red on the bill is usually more extensive than on the Roseate Tern and the back is a darker shade of gray. The primary feathers on the underside have dark tips (light tips in the Roseate Tern). After breeding, the forehead becomes white, and the black cap is reduced to the back of the crown. Length: 31-35 cm.; weight: 110-145 g.

VOICE: A low-pitched, grinding call. Audio (M. Oberle).

HABITAT: Open ocean, occasionally near breeding colonies of other terns.

HABITS: Dives for fish, but on the breeding grounds will also eat some crustaceans and insects. Nests in large, noisy colonies on protected sandy beaches or shell islands on lake shores or coastal beaches in North America and Eurasia. Both sexes build the scrape nest and both incubate the 1-3 eggs over a 23-26 day period. Chicks fledge 24-28 days after hatching. Most Common Terns breeding in the New World migrate great distances to ocean winter grounds from Panama to the Falkland Islands (Malvinas). One bird banded in Finland was recovered 16,000 miles away in Australia!

STATUS AND CONSERVATION: Uncommon in Puerto Rico during the winter, but groups of up to 40 non-breeding adults are seen regularly during the summer checking out the nesting colonies of Roseate Terns. Common Terns banded as far away as Maine and Ontario have been recovered in Puerto Rico. Nesting colonies have always been vulnerable to disturbance by humans, dogs, cats and rats. A new threat to Common Terns and many other seabirds at their nesting colonies is disturbance by noisy, "personal watercraft" boats. In one New Jersey colony, these boats were more likely to cause nesting terns to flee their nests than slower motorboats, especially early in the breeding season. When terns leave their nests unguarded, the eggs or chicks are more likely to be attacked by gulls or other nest predators. At many seabird nesting islands, personal watercraft and other boats should be banned from within 100 meters of shore to avoid fatal disruption of breeding activities. This species declined a century ago due to hunting for feathers, and is now suffering from predation by increasing populations of Ring-billed Gulls in many colonies. The West Indian breeding population is estimated at 50-100 pairs.

RANGE: Breeds in northern North America and Eurasia, as well as in Cuba and the Bahamas.

TAXONOMY: CHARADRIIFORMES; LARIDAE; Sterninae

Breeding plumage -
Photo: G. Beaton

Adult, winter plumage - Photo: J. Saliva

References

Bent, A.C. 1921. Life histories of North American gulls and terns. Smithsonian Instit. U.S. National Museum Bull. 113. (Reprinted by Dover Press, 1963).

Buckley, P. A. and F. G. Buckley. 2000. Breeding Common Terns in the Greater West Indies: status and conservation priorities. Pp. 96-102 in Status and conservation of West Indian seabirds (E. A. Schreiber and D. S. Lee, eds.). Soc. Carib. Ornith., Special Pub. No. 1.

Burger, J. 1998. Effects of motorboats and personal watercraft on flight behavior over a colony of Common Terns. Condor 100(3):528-534.

Burger, J. and M. Gochfeld. 1991. The Common Tern: its breeding biology and social behavior. Columbia Univ. Press, NY.

del Hoyo, J., A. Elliott, and J. Sargatal, eds. 1996. Handbook of Birds of the World, Vol. 3. Hoatzin to Auks. Lynx Edicions, Barcelona.

Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster/ Fireside, NY.

Harrison, P. 1983. Seabirds: an identification guide. Houghton Mifflin, Boston.

Harrison, P. 1987. A field guide to seabirds of the world. Stephen Greene Press, Lexington, MA.

Hume, R.A. 1993. Common, Arctic, and Roseate Terns: an identification review. Brit. Birds. 86:210-217.

Nisbet, I. C. T. 2002. Common Tern (Sterna hirundo). No. 618 in The Birds of North America (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Raffaele, H.A. 1989. A guide to the birds of Puerto Rico and the Virgin Islands. Princeton.

Raffaele, H.A. 1989. Una guía a las aves de Puerto Rico y las Islas Vírgenes. Publishing Resources, Inc., Santurce, PR.

Raffaele, H.A., J.W. Wiley, O.H. Garrido, A.R. Keith, and J.I. Raffaele. 1998. Guide to the birds of the West Indies. Princeton.

Schreiber, E. A. and D. S. Lee. 2000. West Indian seabirds: a disappearing natural resource. Pp. 1-10 in Status and conservation of West Indian seabirds (E. A. Schreiber and D. S. Lee, eds.). Soc. Carib. Ornith., Special Pub. No. 1.

Schreiber, E. A. 2000. Action plan for conservation of West Indian seabirds. Pp. 182-191 in Status and conservation of West Indian seabirds (E. A. Schreiber and D. S. Lee, eds.). Soc. Carib. Ornith., Special Pub. No. 1.

Wiley, J. W. 2000. A bibliography of seabirds in the West Indies. Pp. 192-225 in Status and conservation of West Indian seabirds (E. A. Schreiber and D. S. Lee, eds.). Soc. Carib. Ornith., Special Pub. No. 1.

Common Tern, Spanish text

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