- 18.5–21.3 in
- 47.2–53.1 in
- 18.7–27.6 oz
- Sterne Caspienne (French)
- Charrán caspia, Pagaza Piquirroja (Spanish)
- The Caspian Tern aggressively defends its breeding colony. It will pursue, attack, and chase potential predatory birds, and can cause bloody wounds on the heads of people who invade the colony. The entire colony will take flight, however, when a Bald Eagle flies overhead, exposing the chicks to predation from gulls.
- The world's largest breeding colony is on a small, artificial island in the Columbia River between Oregon and Washington, home to more than 6,000 breeding pairs each year.
- Young Caspian Terns appear to have a difficult time learning to catch fish efficiently. They stay with their parents for long periods of time, and are fed by them even on the wintering grounds. Many young terns do not return to the nesting grounds for several years, remaining instead on the wintering areas.
- The oldest recorded wild Caspian Tern was at least 29 years, 7 months old when it was found in Louisiana in 1989. It had been banded in Michigan in 1959. The average life span of Great Lakes Caspian Terns is estimated to be 12 years.
- Breeds in wide variety of habitats along water, such as salt marshes, barrier islands, dredge spoil islands, freshwater lake islands, and river islands.
- During migration and winter found along coastlines, large rivers and lakes. Roosts on islands and isolated spits.
Almost entirely fish; occasionally crayfish and insects.
- Egg Description
- Buff, sparingly marked with dark spots and sometimes large irregular blotches.
- Condition at Hatching
- Eyes open. Covered with down and able to leave nest (usually after several days).
A scrape in ground. Lined often with dried vegetation, small pebbles, broken shells or other debris. May have elaborate rim of sticks. Nesting colonies occur on island beaches, often near colonies of other bird species.
Flies over water with bill pointing down; plunges into water to catch fish.
There is little information on Caspian Tern populations trends, but the species appears to be stable overall, according to the North American Breeding Bird Survey. In some areas, numbers may be increasing, where birds use man-made dredge spoil islands and dikes for breeding. In other areas, the species is listed as rare or vulnerable because of the scattered nature of breeding colonies. Caspian Tern are declining in Europe. The North American Waterbird Conservation Plan estimates a continental population of between 66,000-70,000 breeders, and lists it a Species of Low Concern. It rates a 10 out of 20 on the Continental Concern Score. Caspian Tern is not on the 2016 State of North America's Birds Watch List. Beach nesting areas vulnerable to disturbance and predation.
- Cuthbert, F. J., and L. R. Wires. 1999. Caspian Tern (Sterna caspia). In The Birds of North America, No. 403 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
- Kushlan, J.A., et al. 2002. Waterbird conservation for the Americas: the North American Waterbird Conservation Plan, version 1. Waterbird Conservation for the Americas. Washington, DC.
- North American Bird Conservation Initiative. 2016. The State of North
America’s Birds 2016. Environment and Climate Change Canada: Ottawa, Ontario.
- USGS Patuxent Wildlife Research Center. 2016. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2015. North American Breeding Bird Survey 1966–2015 Analysis.