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Bridled Tern
Onychoprion anaethetus
At a Glance
A widespread seabird of the tropics and subtropics. Sometimes common over the warm waters of the Gulf Stream, but seldom seen from land in North America except after hurricanes. A handful of pairs have nested in southern Florida since 1987. Very light and buoyant in its flight. Almost never seen resting on ocean; birds at sea may perch on driftwood or floating debris.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Gull-like Birds, Gulls and Terns
Conservation
Low Concern
Habitat
Open Ocean
Region
Florida, Mid Atlantic, Southeast, Texas
Behavior
Direct Flight, Flap/Glide, Hovering, Swooping
Population
700.000
Range & Identification
Migration & Range Maps
Movements of most populations at sea not well known. Present off southeastern states mainly in warmer months, with few records for mid-winter.
Description
14-15" (36-38 cm). Like Sooty Tern but slimmer, a little paler on the back, with a whitish collar across the hindneck. In flight, shows more white in outer tail feathers and on underside of wingtip.
Size
About the size of a Crow, About the size of a Mallard or Herring Gull
Color
Black, Brown, Gray, White
Wing Shape
Long, Narrow, Pointed, Tapered
Tail Shape
Forked, Long, Notched
Songs and Calls
Usually silent; various high-pitched barking notes on breeding grounds.
Call Pattern
Flat
Call Type
Rattle, Raucous, Trill
Habitat
Warm oceans. Spends most of year at sea, over warm waters, generally in offshore waters rather than far out in mid-ocean. In Florida waters often forages along weed lines on landward side of Gulf Stream, so may be found closer to shore than Sooty Tern. Nests on islands with areas of rock rubble, limestone caves, bushes, or other shelter.
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Behavior
Eggs
One. Pale buff, spotted with dark brown or reddish-brown. Incubation is by both parents, 28-30 days.
Young
May leave nest after a few days and hide in nearby cover. Both parents feed young, regurgitating small fish. Age at first flight about 55-63 days; may become independent about a month later.
Feeding Behavior
Forages mostly by flying low, hovering, and dipping down to take items from surface of water; seldom plunge-dives into water. May concentrate where schools of predatory fish are chasing smaller fish to surface. May sometimes feed at night.
Diet
Mostly fish. Feeds mainly on small fish, also small squid, crustaceans, insects.
Nesting
Breeds in isolated pairs or in colonies, often with other terns. Florida nesters were associated with Roseate Terns. Courtship involves high flight by groups or pairs. Male may fly slowly and low over colony, carrying stick or fish, to be pursued by other birds. On ground, two birds bow, strut, turn in circles. Nest site is usually in sheltered spot, such as under ledge, among rock rubble, in small limestone cave, under shrub; sometimes on open ground. Nest is slight scrape in soil, with little or no lining added.
Climate Vulnerability
Conservation Status
Widespread and fairly common in tropical seas.