New York Natural Heritage Program
Roseate Tern
Sterna dougallii Montagu, 1813
Birds

General Description [-]
Roseate Terns are a slender, medium-sized tern with bright orange-red legs, a light grey back, and a deeply forked tail. The bill is entirely black when they arrive in May and shows increasing amounts of red at the base as the breeding season progresses (Donaldson 1968, Cormons 1976).

Identifying Characteristics [-]
Roseate Terns are slender, medium-sized birds, measuring 33-41 cm (13.0-16.1 in.) in total length and weighing 95-130 g (3.4-4.6 oz.). Breeding adults have a black cap and nape. They have pale gray upperparts and white underparts with a slight pinkish appearance that is not very evident during the summer but is sometimes visible in good light. The bill is entirely black when they arrive in the spring and gradually becomes red at the base during the breeding season. The tail is white, deeply forked, and extends well beyond the wings when a bird is standing with its wings folded. The legs and feet are bright red-orange. Hybrid Common X Roseate Terns have been found with intermediate characteristics (Hays 1975). Non-breeding adults have a black mask that extends from the eye to the nape and do not have a black cap. Non-breeding adults also have a white forehead and pale streaks on the rear part of the head just above the nape (hindcrown), white underparts, and a shorter tail (Gochfeld et al. 1998). Nonbreeding adults often also show the rosy blush, which is sometimes more noticeable than on breeding birds (Hays et al. 2006). Juveniles have a brownish cap that extends over the forehead, mid-back, and folded wings that looks coarsely scaled. They have a lower back that is barred with black. First-summer birds have a white forehead. Some second-year birds have a small amount of white above the base of the bill with black speckling (Donaldson 1969). Birds attain full adult plumage by their second winter (National Geographic Society 1983). Roseate Terns are very vocal while they are in their breeding colonies and feeding flocks. At these times, they make loud "pink" and "ki-rik" notes that are sharp and high-pitched. When mobbing an intruder near a nest, they will make a harsh, raspy, single-pitch "aaach" or "kraak" call that sounds like tearing cloth. When attacking terrestrial predators, they will often make a staccato "kekekekekekekeke" sound, sometimes while swooping towards the intruder, ending in a harsh "aaach" when they are nearest. In temperate zones, clutch sizes usually range from one to four eggs. Eggs are various shades of brown, with blackish brown streaks and speckles. It is often difficult to distinguish the eggs of Common Terns and Roseate Terns. However, Roseate Tern eggs are usually more uniformly marked, have more small spots and fewer blotches, and have a darker background color that is less likely to be greenish (Gochfeld et al. 1998).

Characters Most Useful for Identification [-]
The combination of characters that distinguish this species from other adult terns during the breeding season are: orange-red legs and feet, pale grey back, deeply forked tail, and a black bill with red at the base. The rosy tint on the breast is generally not a useful character during the summer because it is barely visible.

Best Life Stage for Proper Identification [-]
Adults in breeding plumage are easiest to identify but juveniles and birds in their winter plumage can also be distinguised from other tern species.

Behavior [-]
Roseate Tern pairs are monogamous for the breeding season. They breed in large colonies frequently with Common Terns (Sterna hirundo) (Bent 1921, Cramp 1985). They have various breeding displays in the air and on the ground (described in detail by Cullen 1960, Cullen 1962, Cramp 1985). Both parents take turns incubating eggs and brooding and feeding chicks. Chicks are semiprecocial at hatching, meaing they aren't fully capable of thermoregulating and feeding themselves. They are already covered in down when they hatch, open their eyes and walk as soon as they are dry (Cormons pers. comm.). Adults exhibit a strong fast, flight with shallow wing beats. To capture fish they use an aerial plunge dive and submerge breifly (Gochfeld et al. 1998) remaining underwater for up to 2.5 seconds (Nisbet 1981, Duffy 1986). Roseate Terns have an impressive array of aerial defenses. When a predator or suspected threat enters their territory, they may circle above them, swoop at them, and/or dive-bomb them while giving an attack call (Gochfeld et al. 1998).

Diet [-]
Roseate Terns primarily eat small marine fish. They show a strong preference for sand eels (Ammodytes americanus) and their diet is not very diverse. Occasionally, they will also eat insects, squid, or small crustateans (Gochfeld et al. 1998).
Roseate Tern Images
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The Best Time to See
Roseate Terns arrive at their breeding grounds in Northeastern North America from late April through May with subadults and juveniles sometimes arriving later into mid-July (Gochfeld et al. 1998, Nisbet 1989). Staging for fall migration occurs in August through September (Nisbet 1984, Shealer and Kress 1994). Roseate Terns are most often present in New York from early-May through September.
J F M A M J J A S O N D
Present Breeding
The time of year you would expect to find Roseate Tern present (blue shading) and breeding (orange shading) in New York.
Similar Species
  • Common Tern (Sterna hirundo)
    The Common Tern has a medium gray back and an orange bill with a black tip. The tail is shorter and does not extend beyond the tips of the wings.
  • Forster's Tern (Sterna forsteri)
    The Forster's Tern has orange legs, a mostly orange black-tipped bill, and slower wingbeats in flight.