Forster's Tern

Sterna forsteri




Gulls, Terns, Skimmers (Laridae)

Code 4


Code 6



Egg Color:

Olive or buff with brown or olive marks

Number of Eggs:


Incubation Days:

23 - 25

Egg Incubator:

Both sexes

Nest Location:

Atop floating reeds or in mud or sand.

Nest Material:

Lined with grass and reeds.





Forster's Tern: Medium-sized tern with pale gray upperparts, black cap, and white underparts. Bill is orange with black tip. Wings are pale gray with paler primaries. Tail is pale gray and deeply forked with dark inner edge and white outer edge. Legs and feet are orange. Sexes are similar. Winter adult lacks black cap but has distinctive black eye patch, gray streaks on head, dark bill, and dull orange legs and feet. Juvnile resembles winter adult but has brown markings on back, nape, head, and upperwings that fade and orange-based black bill that darkens by end of summer.

Range and Habitat

Forster's Tern: Breeds along the Atlantic and Gulf Coasts and in interior British Columbia and California east to the Great Lakes and Mid-Atlantic states. Spends winters along the coasts from California and Virginia southward. In the west, prefers freshwater marshes, whereas in the east, prefers salt marshes.

Breeding and Nesting

Forster's Tern: One to four olive or buff eggs with brown or olive marks are laid on a large platform of dead grass, lined with finer grass, and usually built on a mass of dead marsh vegetation. Incubation ranges from 23 to 25 days and is carried out by both parents.

Foraging and Feeding

Forster's Tern: Diet consists mostly of fish, but also eats insects, small crustaceans, mollusks, frogs, and tadpoles. Catches fish at surface or by plunge diving into water from a perch or a hover; catches insects on the wing or on the water surface; reportedly eats dead fish and frogs exposed by receding ice; occasionally eats bird eggs.


Forster's Tern: Call is a harsh, nasal "beep."

Similar Species

Forster's Tern: Common and Arctic terns have dark outer and white inner tail edges.


Belly, undertail coverts, chest, flanks, and foreneck.

Back, rump, hindneck, wings, and crown.
The area on top of the head of the bird.
Also called the hindneck or collar, it is the back of the neck where the head joins the body.
The primaries are the flight feathers specialized for flight. They are attached to the "hand" equivalent part of the wing.
Parts of a Standing bird X
Head Feathers and Markings X
Parts of a Flying bird X